document_title: Phases of clinical research

question_text: when is a drug studied in patients who have the condition that the drug is intended to treat

text: Phases of clinical research

text: Summary[edit]

text: Clinical trials involving new drugs are commonly classified into four phases. Individual trials may encompass more than one phase. A common example of this is combined phase I/II or phase II/III trials. Therefore, it may be easier to think of early phase studies and late phase studies.[1]  The drug-development process will normally proceed through all four phases over many years. If the drug successfully passes through Phases I, II, and III, it will usually be approved by the national regulatory authority for use in the general population. Phase IV are 'post-approval' studies.

text:
Summary of clinical trial phases

Phase

Primary goal

Dose

Patient monitor

Typical number of participants

Success rate[2]

Notes

Preclinical

Testing of drug in non-human subjects, to gather efficacy, toxicity and pharmacokinetic information

unrestricted

scientific researcher

not applicable (in vitro and in vivo only)

Phase 0

Pharmacokinetics; particularly, oral bioavailability and half-life of the drug

very small, subtherapeutic

clinical researcher

10 people

often skipped for phase I

Phase I

Testing of drug on healthy volunteers for safety; involves testing multiple doses dose-ranging

often subtherapeutic, but with ascending doses

clinical researcher

20–100 normal healthy volunteers (or for cancer drugs, cancer patients)

approximately 70%

determines whether drug is safe to check for efficacy

Phase II

Testing of drug on patients to assess efficacy and side effects

therapeutic dose

clinical researcher

100–300 patients with specific diseases

approximately 33%

determines whether drug can have any efficacy; at this point, the drug is not presumed to have any therapeutic effect whatsoever

Phase III

Testing of drug on patients to assess efficacy, effectiveness and safety

therapeutic dose

clinical researcher and personal physician

300–3,000 patients with specific diseases

25–30%

determines a drug's therapeutic effect; at this point, the drug is presumed to have some effect

Phase IV

Postmarketing surveillance – watching drug use in public

therapeutic dose

personal physician

anyone seeking treatment from their physician

N/A

watch drug's long-term effects

text: Pre-clinical studies[edit]

text: Before pharmaceutical companies start clinical trials on a drug, they conduct extensive pre-clinical studies. These involve in vitro (test tube or cell culture) and in vivo (animal) experiments using wide-ranging doses of the study drug to obtain preliminary efficacy, toxicity and pharmacokinetic information. Such tests assist pharmaceutical companies to decide whether a drug candidate has scientific merit for further development as an investigational new drug.

text: Phase 0[edit]

text: Phase 0 is a recent designation for optional exploratory trials conducted in accordance with the United States Food and Drug Administration's (FDA) 2006 Guidance on Exploratory Investigational New Drug (IND) Studies.[3] Phase 0 trials are also known as human microdosing studies and are designed to speed up the development of promising drugs or imaging agents by establishing very early on whether the drug or agent behaves in human subjects as was expected from preclinical studies. Distinctive features of Phase 0 trials include the administration of single subtherapeutic doses of the study drug to a small number of subjects (10 to 15) to gather preliminary data on the agent's  pharmacokinetics (what the body does to the drugs).[4]

text: A Phase 0 study gives no data on safety or efficacy, being by definition a dose too low to cause any therapeutic effect. Drug development companies carry out Phase 0 studies to rank drug candidates in order to decide which has the best pharmacokinetic parameters in humans to take forward into further development. They enable go/no-go decisions to be based on relevant human models instead of relying on sometimes inconsistent animal data.

text: Phase I[edit]

text: Phase I trials were formerly referred to as “first-in-man studies” but the field generally moved to the gender-neutral language phrase "first-in-humans" in the 1990s;[5] these trials are the first stage of testing in human subjects.[6] They are designed to test the safety, side effects, best dose, and formulation method for the drug.[7]

text: Normally, a small group of 2–100 healthy volunteers will be recruited.[2][6] These trials are often conducted in a clinical trial clinic, where the subject can be observed by full-time staff. These clinical trial clinics are often run by contract research organization (CROs) who conduct these studies on behalf of pharmaceutical companies or other research investigators. The subject who receives the drug is usually observed until several half-lives of the drug have passed. This phase is designed to assess the safety (pharmacovigilance), tolerability, pharmacokinetics, and pharmacodynamics of a drug. Phase I trials normally include dose-ranging, also called dose escalation studies, so that the best and safest dose can be found and to discover the point at which a compound is too poisonous to administer.[8] The tested range of doses will usually be a fraction[quantify] of the dose that caused harm in animal testing. Phase I trials most often include healthy volunteers. However, there are some circumstances when clinical patients are used, such as patients who have terminal cancer or HIV and the treatment is likely to make healthy individuals ill. These studies are usually conducted in tightly controlled clinics called CPUs (Central Pharmacological Units), where participants receive 24-hour medical attention and oversight. In addition to the previously mentioned unhealthy individuals, “patients who have typically already tried and failed to improve on the existing standard therapies"[1] may also participate in phase I trials.  Volunteers are paid a variable inconvenience fee for their time spent in the volunteer center.

text: Before beginning a phase I trial, the sponsor must submit an Investigational New Drug application to the FDA detailing the preliminary data on the drug gathered from cellular models and animal studies.

text: Phase I trials can be further divided:

text: Phase II[edit]

text: Once a dose or range of doses is determined, the next goal is to evaluate whether the drug has any biological activity or effect.[1]  Phase II trials are performed on larger groups (100–300) and are designed to assess how well the drug works, as well as to continue Phase I safety assessments in a larger group of volunteers and patients.  Genetic testing is common, particularly when there is evidence of variation in metabolic rate.[1]  When the development process for a new drug fails, this usually occurs during Phase II trials when the drug is discovered not to work as planned, or to have toxic effects.

text: Phase II studies are sometimes divided into Phase IIA and Phase IIB. There is no formal definition for these 2 sub-categories, but generally:

text:
Phase IIA studies are usually pilot studies designed to demonstrate clinical efficacy or biological activity ('proof of concept' studies);
Phase IIB studies look to find the optimum dose at which the drug shows biological activity with minimal side-effects (‘definite dose-finding’ studies).

text: Some trials combine Phase I and Phase II, and test both efficacy and toxicity.

text: Some researchers argue that phase II studies are generally smaller than they ought to be.[1]

text: Success rate[edit]

text: Phase II clinical programs historically have experienced the lowest success rate of the four development phases.  In 2010, the percentage of phase II trials that proceeded to phase III was 18%,[10]  and only 30.7% of developmental candidates advanced from Phase II to Phase III in a large study of trials from 2006-2015.[11]

text: Phase III[edit]

text: This phase is designed to assess the effectiveness of the new intervention and, thereby, its value in clinical practice.[1]  Phase III studies are randomized controlled multicenter trials on large patient groups (300–3,000 or more depending upon the disease/medical condition studied) and are aimed at being the definitive assessment of how effective the drug is, in comparison with current 'gold standard' treatment. Because of their size and comparatively long duration, Phase III trials are the most expensive, time-consuming and difficult trials to design and run, especially in therapies for chronic medical conditions. Phase III trials of chronic conditions or diseases often have a short follow-up period for evaluation, relative to the period of time the intervention might be used in practice.[1]  This is sometimes called the "pre-marketing phase" because it actually measures consumer response to the drug.

text: It is common practice that certain Phase III trials will continue while the regulatory submission is pending at the appropriate regulatory agency. This allows patients to continue to receive possibly lifesaving drugs until the drug can be obtained by purchase. Other reasons for performing trials at this stage include attempts by the sponsor at "label expansion" (to show the drug works for additional types of patients/diseases beyond the original use for which the drug was approved for marketing), to obtain additional safety data, or to support marketing claims for the drug. Studies in this phase are by some companies categorized as "Phase IIIB studies."[12]

text: While not required in all cases, it is typically expected that there be at least two successful Phase III trials, demonstrating a drug's safety and efficacy, in order to obtain approval from the appropriate regulatory agencies such as FDA (USA), or the EMA (European Union).

text: Once a drug has proved satisfactory after Phase III trials, the trial results are usually combined into a large document containing a comprehensive description of the methods and results of human and animal studies, manufacturing procedures, formulation details, and shelf life. This collection of information makes up the "regulatory submission" that is provided for review to the appropriate regulatory authorities[13] in different countries. They will review the submission, and, it is hoped, give the sponsor approval to market the drug.

text: Most drugs undergoing Phase III clinical trials can be marketed under FDA norms with proper recommendations and guidelines through a New Drug Application (NDA) containing all manufacturing, pre-clinical, and clinical data. In case of any adverse effects being reported anywhere, the drugs need to be recalled immediately from the market.  While most pharmaceutical companies refrain from this practice, it is not abnormal to see many drugs undergoing Phase III clinical trials in the market.[14]

text: Success rate[edit]

text: As of 2010, about 50% of drug candidates either fail during the Phase III trial or are rejected by the national regulatory agency.[15]

text: Phase II/III cost

text: The amount of money spent on Phase II/III trials depends on numerous factors, with therapeutic area being studied and types of clinical procedures as key drivers; Phase II studies may cost as much as $20 million, and Phase III as much as $53 million.[16]

text: Phase IV[edit]

text: A Phase IV trial is also known as postmarketing surveillance trial, or informally as a confirmatory trial. Phase IV trials involve the safety surveillance (pharmacovigilance) and ongoing technical support of a drug after it receives permission to be sold (e.g. after approval under the FDA Accelerated Approval Program).[17] Phase IV studies may be required by regulatory authorities or may be undertaken by the sponsoring company for competitive (finding a new market for the drug) or other reasons (for example, the drug may not have been tested for interactions with other drugs, or on certain population groups such as pregnant women, who are unlikely to subject themselves to trials).[2][6] The safety surveillance is designed to detect any rare or long-term adverse effects over a much larger patient population and longer time period than was possible during the Phase I-III clinical trials.[6][17] Harmful effects discovered by Phase IV trials may result in a drug being no longer sold, or restricted to certain uses; recent examples involve cerivastatin (brand names Baycol and Lipobay), troglitazone (Rezulin) and rofecoxib (Vioxx). The minimum time period mandatory for Phase IV clinical trials is 2 years.[citation needed]

text: Overall cost[edit]

text: The entire process of developing a drug from preclinical research to marketing can take approximately 12 to 18 years and often costs well over $1 billion.[18][19]


document_title: The Mountain Between Us (film)

question_text: who plays in the movie the mountain between us

root

text: The Mountain Between Us (film)

text: Plot[edit]

text: After the cancellation of their flights out of Boise Airport due to stormy weather, neurosurgeon Dr. Ben Bass (Idris Elba) and photojournalist Alex Martin (Kate Winslet) contact Walter (Beau Bridges), a local private pilot to get to Alex's wedding (scheduled for the following day) and Ben's emergency surgery appointment in Baltimore, Maryland. They board an uncharted flight with Walter's dog. Shortly after takeoff, Walter suffers a stroke, causing the plane to crash on a mountaintop. Ben, Alex and the dog survive the incident with various injuries, but Walter is killed.

tag: p

text: Ben buries Walter and tends to Alex's wounds, realizing they must find civilization for any hope of survival. Alex asks Ben to leave her behind as he has a better chance of surviving, but Ben refuses. Instead, he climbs a peak to see if there are any structures nearby. On his descent, he nearly falls off a cliff face. Meanwhile, a cougar approaches the plane wreckage, attacking and injuring the dog. The cougar then approaches Alex within the plane wreckage, but she wounds it with a flare. Ben returns to find a blood trail and rushes to the plane. He provides medical attention to the dog and later retrieves the body of the cougar and barbecues it for food.

text: Stranded for days with dwindling sustenance, Ben and Alex find strength in each other. Alex becomes skeptical that help will come, though Ben continues to insist they wait for help. After a heated argument, they both sleep, with Alex resolving that she will leave. At first light, she proceeds to leave the wreckage and start a descent down the mountain. Ben wakes and gives chase, eventually catching up with Alex, and they make up over past grievances. While making shelter in a cave, Alex uses her camera to locate a man-made structure and spots a reflective material flashing at her. They agree to make it down to this structure. As they continue their walk, they become separated from the dog. Ben goes after him and finds an abandoned cabin. As he looks through it, Alex feels the ground beneath her cracking. She realizes she is standing over thin ice, and she falls through into the ice cold water. Ben hears the cracking and sees Alex fall down. He runs over and pulls her out, but she is unconscious and almost blue. Ben brings her to the cabin and starts a fire to warm her up. He takes a risk of administrating her an injection he crafted out of materials in the cabin in a resourceful way. A couple of days later, Alex eventually wakes up to the sound Ben makes with the piano in the cabin.

text: The first time Ben leaves Alex alone in the cabin, she goes through his personal things and again listens to a voicemail recording from his wife. Ben catches Alex in the act. She says she didn't mean to be nosy, but she just wants to know something about him, especially since he has disclosed so little about himself and he never talks about his wife. He finally tells her his wife died two years ago from a brain tumour.

text: When Ben tells Alex he is going outside to get more wood for the fire, the culmination of all of their experiences together finally overcomes them. No longer able to resist each other, they have sex. As Ben sleeps afterwards, Alex takes his picture. Deciding that they still won't make it, Alex again asks Ben to leave her behind to find help and return. Ben initially agrees but has regrets about leaving her behind just for a moment. He returns once more and they begin to press forward again. As they make their way down, Alex begins to tire quickly. However, Ben still refuses to leave her behind. They fall asleep in the woods. Eventually, they find a timber yard on the mountain and they make their way to it. Ben gets his leg caught in a bear trap. Alex keeps going and she's rescued by a truck driver, who goes back and rescues Ben.

text: Ben wakes up in the hospital and goes to Alex's room, where he sees her with Mark, her fiancé. Mark praises Ben for saving Alex, to which Ben replies she saved him, and leaves the room, heartbroken. Some time after, Mark tells Alex that "I told myself that if you ever lost a part of you (an arm or leg in her dangerous job as a photojournalist), I would still love you." But now, it's obvious to him that he has lost her heart.

text: Alex tries calling Ben, but he declines her phone calls until he receives pictures of him and Alex on the mountain. This encourages Ben to call Alex. They meet up at a restaurant in Manhattan, where it is revealed that Alex is now a part-time teacher who is uncomfortable flying, and Ben is now working as a consultant in trauma clinics as his frostbitten hands have not recovered enough for him to operate. Ben admits that he did not call her back because he thought she would be married, and Alex responds by saying that she couldn't go through with it and she loved Ben while they were together on the mountain. After leaving the restaurant, Ben admits to Alex that they survived because they fell in love. She dismisses her feelings and reminds him of what he said before on the mountain- that 'the heart is just a muscle.' They hug goodbye and as they depart in opposite directions, they feel deep regrets, burst into tears and run back into each other's arms.

text: Cast[edit]

text:
Idris Elba as Dr. Ben Bass, a surgeon
Kate Winslet as Alex Martin, a photojournalist
Dermot Mulroney as Mark, Alex’s fiancé
Beau Bridges as Walter, the pilot of the charter plane
Raleigh and Austin as Walter's dog, later adopted by Ben

tag: ul

text: Production[edit]

text: The project was first developed in January 2012, with Mexican director Gerardo Naranjo set to direct a script by J. Mills Goodloe.[8] In August 2012, Scott Frank was hired to re-write the script.[9] In November 2014, Hany Abu-Assad replaced Naranjo,[10] and Chris Weitz was later hired to re-write the script.[11]

text: Abu-Assad has said of the film, "I really didn’t see an epic love story against the background of survival, I think optimism and hope is crucial to survive. And to go on with your life even if you’ve had a lot of bad luck. So if you give (in) to the bad luck, you will die. (But) if you fight the bad luck, you have a better chance to survive and make your life better. This is very simple wisdom, yes? But still very crucial especially in these kind of days, when everybody feels entitled to their good luck."[12]

text: Casting[edit]

text: The film went through several lead casting changes. In March 2012, it was announced that Michael Fassbender would star as Bass,[13] but by September 2014, Fassbender dropped out due to a scheduling conflict, and Charlie Hunnam replaced him. Margot Robbie also came on board to star as Alex.[14] In November 2014, Robbie dropped out of the project, and Rosamund Pike entered negotiations for the lead role.[10] In December 2015, both Hunnam and Pike dropped out.[11]

text: In February 2016, Idris Elba came on board,[15] followed by Kate Winslet in June 2016.[16] Dermot Mulroney joined the cast as Winslet's character's fiancé in early February 2017.[17]

text: Filming[edit]

text: Principal photography started on December 5, 2016, in Vancouver and continued until February 24, 2017.[18][19] Elba and Winslet filmed scenes at the Vancouver International Airport on December 6, 2016,[20] and Elba also filmed scenes at the Abbotsford International Airport on December 7, 2016.[21] Filming stopped for Christmas holidays, from December 20, 2016, to January 3, 2017.[22]

text: Filming resumed around Invermere and Panorama Mountain Village on January 4, 2017.[23] Winslet was spotted filming scenes at Eagle Ridge Hospital in Port Moody on February 8, 2017.[24]

text: Most of the filming took place in Canada, on the border of Alberta and British Columbia. Abu-Assad has described the locations as having very cold temperatures, and tough and harsh filming conditions. Many scenes were shot on a mountaintop, and he and the crew had to drive 40 minutes before reaching the film's base camp. If the weather was okay, they could board the helicopter to reach their destination along with their supplies.[12]

text: On July 19, 2017, Winslet and Elba were spotted in London re-shooting some scenes for the film.[25]

text: Music[edit]

text: German-Iranian composer Ramin Djawadi composed the music for the film.[26] The official trailer for the movie was released with "Dusk Till Dawn" by Zayn and Sia as the official soundtrack.

text: Releases[edit]

text: The film had its premiere at the 2017 Toronto International Film Festival, on September 9, 2017.[27] The film was initially set for release in the United States on October 20, 2017,[28] but was later moved up to October 6, 2017.[7]

text: Box office[edit]

text: As of December 21, 2017[update], The Mountain Between Us has grossed $30.3 million in the United States and Canada, and $30.7 million in other territories, for a worldwide total of $61.1 million, against a production budget of $35 million.[3]

text: In the United States and Canada, the film was released alongside Blade Runner 2049 and My Little Pony: The Movie, and was expected to gross $11–12 million from 3,088 theaters in its opening weekend.[29] It ended up debuting to $10.1 million, finishing second at the box office, behind Blade Runner 2049 ($32.5 million).[30] The film dropped 47% in its second weekend, making $5.7 million and falling to 5th.[31]

text: Critical response[edit]

text: On Rotten Tomatoes, the film has an approval rating of 41%, based on 146 reviews, with an average rating of 5.2/10. The site's critical consensus reads, "The Mountain Between Us may be too far-fetched for some viewers to appreciate, but it's elevated by reliably engaging performances from Idris Elba and Kate Winslet."[32] On Metacritic, the film has a weighted average score of 48 out of 100, based on 37 critics, indicating "mixed or average reviews".[33] Audiences polled by CinemaScore gave the film an average grade of "A−" on an A+ to F scale.[30]

text: Jordan Mintzer of The Hollywood Reporter described the film as "an easily digestible love story-come-survival tale that tosses two excellent actors in the snow and lets them do their thing," before concluding that "what really helps Mountain overcome its far-fetched scenario is the pairing of Winslet and Elba, who know how to turn up the charm tenfold yet make Alex and Ben seem (mostly) like real people."[34] Tim Grierson of ScreenDaily noted that the film "struggles to balance its life-or-death stakes with its far more florid love story," but added that "the considerable chemistry between Kate Winslet and Idris Elba certainly helps sell this tearjerker."[35]

text: In his review for Variety, Peter Debruge described it as "a movie in which neither the subzero temperature nor the romantic heat penetrates more than skin deep."[36] Also criticising the film, Steve Pond of TheWrap found it unnecessarily lengthy and said that "a love story cheapens the grand survival story."[37] Ignatiy Vishnevetsky of The A.V. Club criticized the central characters as "a couple of one-note personality-test types" with "zero romantic chemistry," and wrote that the script "actually tones down the howling outrageousness of Martin’s novel, which seems to miss the point. But, structurally, it’s the same junk. Problems pop out of nowhere and resolve themselves, while torturous motivations attempt to explain why characters would withhold basic information from one another for weeks..."[38]


document_title: Bornu Empire

question_text: factors that contributed to the decline and fall of borno empire

text: Bornu Empire

text: Exile from Kanem[edit]

text: After decades of internal conflict, rebellions and outright invasion from the Bulala, the once-strong Sayfawa Dynasty was forced out of Kanem and back into the nomadic lifestyle they had abandoned nearly 700 years earlier. Around 1380, the Kanembu finally overcame attacks from neighboring Arabs, Berbers and Hausa, to found a new state in Bornu. Over time, the intermarriage of the Kanembu and Bornu peoples created a new people and language, the Kanuri.

text: Early rule[edit]

text: Even in Bornu, the Sayfawa Dynasty's troubles persisted. During the first three-quarters of the 15th century, for example, fifteen mais occupied the throne. Then, around 1455, Mai Ali Dunamami defeated his rivals and began the consolidation of Bornu. He built a fortified capital at Ngazargamu (in present-day Nigeria), to the west of Lake Chad. This was the first permanent home a Sayfawa mai had enjoyed in a century. So successful was the Sayfawa rejuvenation that by the early 16th century Mai Ali Gaji (1455–1487) was able to defeat the Bulala and retake Njimi, the former capital. The empire's leaders, however, remained at Ngazargamu because its lands were more productive agriculturally and better suited to the raising of cattle. Ali Gaji was the first ruler of the empire to assume the title of Caliph.[3]

text: Kanem-Bornu Period[edit]

text: With control over both capitals, the Sayfawa dynasty became more powerful than ever. The two states were merged, but political authority still rested in Bornu. Kanem-Bornu peaked during the reign of the statesman Mai Idris Alooma (c. 1571–1603).

text: Idris Alooma[edit]

text: Idris Alooma is remembered for his military skills, administrative reforms, and Islamic piety. His main adversaries were the Hausa to the west, the Tuareg and Tubu to the north, and the Bulala to the east. His innovations included the employment of fixed military camps (with walls); permanent sieges and "scorched earth" tactics, where soldiers burned everything in their path; armored horses and riders; and the use of Berber camelry, Kotoko boatmen, and iron-helmeted musketeers trained by Turkish military advisers.[4] His active diplomacy featured relations with Tripoli, Egypt, and the Ottoman Empire, which sent a 200-member ambassadorial party across the desert to Alooma's court at Ngazargamu. Alooma also signed what was probably the first written treaty or cease-fire in Chadian history.

text: Alooma introduced a number of legal and administrative reforms based on his religious beliefs and Islamic law (sharia). He sponsored the construction of numerous mosques and made a pilgrimage (hajj) to Mecca, where he arranged for the establishment of a hostel to be used by pilgrims from his empire. As with other dynamic politicians, Alooma's reformist goals led him to seek loyal and competent advisers and allies, and he frequently relied on slaves who had been educated in noble homes. Alooma regularly sought advice from a council composed of heads of the most important clans. He required major political figures to live at the court, and he reinforced political alliances through appropriate marriages. (Alooma himself was the son of a Kanuri father and a Bulala mother.)

text: Kanem-Bornu under Alooma was strong and wealthy. Government revenue came from tribute (or booty, if the recalcitrant people had to be conquered), sales of slaves, and duties on and participation in trans-Saharan trade. Unlike West Africa, the Chadian region did not have gold. Still, it was central to one of the most convenient trans-Saharan routes. Between Lake Chad and Fezzan lay a sequence of well-spaced wells and oases, and from Fezzan there were easy connections to North Africa and the Mediterranean Sea. Many products were sent north, including natron (sodium carbonate), cotton, kola nuts, ivory, ostrich feathers, perfume, wax, and hides, but the most important of all were slaves. Imports included salt, horses, silks, glass, muskets, and copper.

text: Alooma took a keen interest in trade and other economic matters. He is credited with having the roads cleared, designing better boats for Lake Chad, introducing standard units of measure for grain, and moving farmers into new lands. In addition, he improved the ease and security of transit through the empire with the goal of making it so safe that "a lone woman clad in gold might walk with none to fear but God."[citation needed]

text: Successors[edit]

text: Most of the successors of Idris Alooma are only known from the meagre information provided by the Diwan. Some of them are noted for having undertaken the pilgrimage to Mecca others for their piety. In the eighteenth century Bornu was affected by several long-lasting famines.[5]

text: Decline and Fall[edit]

text: The administrative reforms and military brilliance of Alooma sustained the empire until the mid-17th century, when its power began to fade. By the late 18th century, Bornu rule extended only westward, into the land of the Hausa of modern Nigeria. The empire was still ruled by the mai who was advised by his councilors (kokenawa) in the state council or "nokena".[6]

text: Fulani Jihad[edit]

text: Around that time, Fulani people, invading from the west, were able to make major inroads into Bornu. By the early 19th century, Kanem-Bornu was clearly an empire in decline, and in 1808 Fulani warriors conquered Ngazargamu. Usman dan Fodio led the Fulani thrust and proclaimed a holy war (the Fulani War) on the allegedly irreligious Muslims of the area. His campaign eventually affected Kanem-Bornu and inspired a trend toward Islamic orthodoxy, but a Muslim scholar-turned-statesman, Muhammad al-Amin al-Kanemi, contested the Fulani advance.

text: Muhammad al-Kanemi[edit]

text: Muhammad al-Amin al-Kanemi was a Muslim scholar and non-Sayfawa commander who had put together an alliance of Shuwa Arabs, Kanembu, and other seminomadic peoples. He eventually built in 1814 a capital at Kukawa (in present-day Nigeria). Sayfawa mais remained titular monarchs until 1846. In that year, the last mai, in league with the Ouaddai Empire, precipitated a civil war. It was at that point that Kanemi's son, Umar, became king, thus ending one of the longest dynastic reigns in international history.

text: Post-Sayfawa Era[edit]

text: Although the dynasty ended, the kingdom of Kanem-Bornu survived. Umar eschewed the title mai for the simpler designation shehu (from the Arabic shaykh), could not match his father's vitality, and gradually allowed the kingdom to be ruled by advisers (wazirs). Bornu began a further decline as a result of administrative disorganization, regional particularism, and attacks by the militant Ouaddai Empire to the east. The decline continued under Umar's sons. In 1893, Rabih az-Zubayr led an invading army from eastern Sudan and conquered Bornu. Following his expulsion shortly thereafter, the state was absorbed by the British ruled entity which eventually became known as Nigeria. From that point on, a remnant of the old kingdom was (and still is) allowed to continue to exist in subjection to the various Governments of the country as the Borno Emirate.


document_title: Albus Dumbledore

question_text: when did the actor who played dumbledore die

text: Albus Dumbledore

text: Character development

text: The author has stated that she enjoys writing Dumbledore because he "is the epitome of goodness."[6] Rowling said that Dumbledore speaks for her, as he "knows pretty much everything" about the Harry Potter universe.[7] Rowling mentioned that Dumbledore regrets "that he has always had to be the one who knew, and who had the burden of knowing. And he would rather not know."[8] As a mentor to the central character Harry Potter, "Dumbledore is a very wise man who knows that Harry is going to have to learn a few hard lessons to prepare him for what may be coming in his life. He allows Harry to get into what he wouldn't allow another pupil to do, and he also unwillingly permits Harry to confront things he’d rather protect him from."[9] In a 1999 interview, Rowling stated that she imagined Dumbledore "more as a John Gielgud type, you know, quite elderly and – and quite stately."[10] During his time as a student, Dumbledore was in Gryffindor House.[11] Rowling said in an interview that Dumbledore was about 150 years old.[12] However, on her website, she states that Dumbledore was born in 1881, making him either 115 or 116 when he died.[13]

text: On 19 October 2007, Rowling was asked by a young fan whether Dumbledore finds "true love." Rowling said that she always thought of Dumbledore as being homosexual and that he had fallen in love with Gellert Grindelwald, which was Dumbledore's "great tragedy"; Rowling did not explicitly state whether Grindelwald returned his affections.[14][15][16] Rowling explains this further by elaborating on the motivations behind Dumbledore's flirtation with the idea of wizard domination of Muggles: "He lost his moral compass completely when he fell in love and I think subsequently became very mistrustful of his own judgement in those matters so became quite asexual. He led a celibate and a bookish life."[17]

text: Appearances

text: Harry Potter and the Philosopher's Stone

text: In the opening chapter of the first novel of the series, Dumbledore arrives at number four, Privet Drive in Little Whinging, Surrey. When the evil wizard Lord Voldemort kills Harry's parents before being reduced to a lesser form, Dumbledore decides to place the now-orphaned Harry in the home of Vernon and Petunia Dursley. He knows that Harry will be protected by the special magic caused by his mother's sacrifice, after he evokes the magic of the bond of blood and Harry's aunt, his mother's sister - Petunia Evans Dursley, sealed it by accepting her nephew into her home. This old magic of binding love renders Voldemort incapable of touching Harry. Dumbledore leaves Harry upon the doorstep of the Dursley home with a letter explaining the situation. He departs with the final phrase, "Good luck, Harry."

text: When Harry arrives at Hogwarts, Dumbledore tells him about the secrets of the Mirror of Erised, claiming that when he looks into it, he sees himself "holding a pair of thick, woollen socks." Harry later recalls in the final book that this was probably the only dishonest answer Dumbledore ever gave him. He is also responsible for somehow enchanting the Mirror so that it hides the Philosopher's Stone and only someone who looked into the Mirror and whose desire was "to find the Stone ... but not use it" would receive it, as anybody else would only see themselves using the Stone due to the Mirror's special magic. He is called out to the Ministry of Magic by a false message on the night when Professor Quirinus Quirrell, Harry Potter, Ron Weasley, and Hermione Granger enter the dungeons to retrieve the Stone, but realises during the trip that he is needed at Hogwarts and returns in time to rescue Harry from Quirrell and Voldemort. He also has a final conversation with Harry after the events down in the dungeons and tells him that he is too young to comprehend the information about why Voldemort attempts to kill him.

text: Harry Potter and the Chamber of Secrets

text: In the second novel, Dumbledore suspects that Tom Riddle is somehow involved in the attacks on the muggle born students, as he says, when asked who is the culprit, "not who, but how?" A younger Dumbledore appears in Riddle's diary, when Harry sees his memory, and asks Riddle if he knows anything about the attacks on the students. During the last half of the novel, Lucius Malfoy forces the school's other eleven governors to suspend Dumbledore as Headmaster in the wake of attacks by a basilisk in the school when the Chamber of Secrets is opened. Dumbledore is reinstated when the governors discover that Ginny Weasley was taken into the Chamber of Secrets and Lucius is found to have coerced the other governors into suspending him.

text: At the beginning of the third novel, Dumbledore is forced to accept Dementors onto his school's grounds for the protection of his students from Sirius Black, the supposed murderer and accessory to murder, who had escaped from Azkaban. After Black's breach into Hogwarts, Dumbledore issues orders to close every entrance to the school and grounds. After Harry falls off his broomstick during a Quidditch match because of the Dementors, Dumbledore becomes uncharacteristically angry with them and uses his wand to cause Harry to levitate safely to the ground. Later in that book, Dumbledore suggests Hermione Granger use her Ministry-approved Time-Turner to go back three hours to save Buckbeak the hippogriff and Sirius from their unjust executions.

text: Harry Potter and the Goblet of Fire

text: In the fourth novel, Dumbledore introduces the Triwizard Tournament. He also serves as a judge during the entire event. When Harry's name comes out of the Goblet of Fire, Dumbledore is not enraged, but remains calm; simply asking Harry whether he had himself, or had asked an older student to submit his name (although in the film version he does get angry to the point of manhandling Harry). When Harry answers no, he believes him. By the end of the book, Dumbledore's fears are realised when Harry returns from his encounter with Voldemort clutching the dead body of Cedric Diggory and when Mad-Eye Moody (being impersonated by Barty Crouch Jr, through Polyjuice Potion) takes Harry away from Dumbledore and to his office inside the castle. Dumbledore immediately becomes suspicious and heads straight towards Moody's office with Minerva McGonagall and Severus Snape to save Harry and to interrogate Crouch. Afterwards, Dumbledore listens to Harry's eyewitness account about Voldemort's return. Harry though, only wakes up later to find Minister for Magic Cornelius Fudge in the hospital wing arguing with McGonagall and Dumbledore. In the end, Fudge and Dumbledore "part ways" after an argument about the situation of Voldemort's return and the consequences that would follow should Fudge remain in denial of this fact.

text: In the fifth book, Dumbledore is demoted from Chief Warlock of the Wizengamot, voted out of the Chairmanship of the International Confederation of Wizards, and is almost stripped of his Order of Merlin First Class due to his speeches regarding the return of Voldemort, although it is reported that he is unconcerned as long as he is not taken off the Chocolate Frog cards. Meanwhile, the Ministry of Magic does everything they can to discredit him and Harry – mainly through the Daily Prophet. At the beginning of the book, Dumbledore enrages Fudge when he stops by at Harry's hearing with a witness (Arabella Figg) to ensure that he is not expelled. While Harry feels better when Dumbledore assists him, he becomes annoyed to the point of being angry that the headmaster refuses to speak to or even look at him.

text: During the following year at Hogwarts, the Ministry passes Educational Decree Twenty-two, allowing Fudge to place Dolores Umbridge to the post of Defence Against the Dark Arts teacher (after Dumbledore failed to find a suitable candidate). Through her, Fudge gradually gains power over Hogwarts and Dumbledore, who he fears is building an under-age wizard army to overthrow the Ministry. Umbridge forbids practical defence practice in her classes, forcing Harry, Ron, and Hermione to form Dumbledore's Army (a defence group led by Harry) with fellow friends. It is when the Ministry discovers the D.A. that Dumbledore, choosing to accept the responsibility, falsely claims that the organisation was his own subversive creation, and allows himself to be removed as headmaster (for the second time) rather than allow Harry to be expelled.

text: Dumbledore is not heard of again in the book until he arrives in the Department of Mysteries to aid the Order in the battle against the Death Eaters. He subdues all the Death Eaters, except for Bellatrix Lestrange, and binds them with an Anti-Disapparition Jinx to prevent them from magically escaping. He then saves Harry from the Avada Kedavra curse conjured by Voldemort and engages in a ferocious duel with the Dark Lord. This culminates in Voldemort's attempting to possess Harry in an attempt to make Dumbledore kill the boy. Voldemort is forced to leave Harry's body and flee with Bellatrix after this ruse fails. Many ministry officials' having witnessed the end of the battle, Dumbledore is reinstated as headmaster and retrieves all his distinctions. Towards the end of the book, Dumbledore explains to Harry that Voldemort chose him as his equal and that one must kill the other in the end, and confesses that his great affection for Harry has clouded his judgement.

text: Harry Potter and the Half-Blood Prince

text: In the sixth book, Dumbledore fetches Harry from Privet Drive and takes him to persuade Horace Slughorn to rejoin the Hogwarts staff. Harry notices that Dumbledore's right hand is shrivelled and black. During the school year, Dumbledore teaches Harry of events in Voldemort's past that he feels are of immense importance. Using the Pensieve, they visit the memories of others, which contain important information about Voldemort's life and his genocidal rise to power. While using the pensieve, Harry sees a vision of Dumbledore's first encounter with Voldemort, then a disturbed young orphan named Tom Riddle; Dumbledore had known from the beginning that the boy was dangerous, but believed that Hogwarts would change him.

text: It is learned that Voldemort created six Horcruxes to gain immortality and that they must all be destroyed before Harry goes after the final piece of Voldemort's soul in the Dark Lord's body. Harry also repeatedly warns Dumbledore in most of their lessons that Draco Malfoy, is working for Voldemort. Dumbledore refuses to take any action against Draco, and instead tells Harry that he already knows more about what is happening than Harry does.

text: By the end of the book, Dumbledore and Harry set out to the cave where Dumbledore believes a Horcrux resides. In the cave, Dumbledore drinks a potion inside the Horcrux's container; while drinking it, he begins to scream, seemingly enduring mental torture and being weakened. Dumbledore begins to call out for water after he finishes the potion, and Harry, realising he has no other choice, dips the goblet into the lake to give him a drink. When he does this though, all the Inferi that reside in the lake grab at Harry and attempt to drag him down and drown him in the lake. Dumbledore suddenly recovers, thanks to the water, and conjures a fire lasso around them. Dumbledore takes the horcrux (a locket) and both make their way back out of the cave and back to Hogsmeade. When they return, Madam Rosmerta informs them that the Dark Mark was conjured over the Astronomy Tower. In the tower, Dumbledore enjoins Harry not to interfere in the events that are about to take place there, and places him in a body-binding curse under his invisibility cloak. Hidden, Harry is unable to intervene as Dumbledore (now extremely weak) is disarmed by Draco. Dumbledore is conversing with Draco about the plot to kill him, when several other Death Eaters enter the tower and try to persuade Draco to kill Dumbledore. When Draco hesitates, Snape appears and performs the Killing Curse on Dumbledore, only after Dumbledore pleads with Snape saying, "Severus, please ...". To what Dumbledore was referring is not revealed until the seventh book. Dumbledore dies in Hogwarts' grounds.

text: Shortly after his death, Dumbledore's portrait magically appears in the Headmaster's office. His funeral is attended by students, Hogwarts staff, members of the Ministry of Magic, ghosts, centaurs, merpeople and others who wish to pay their respects. Shrouded in purple velvet, he is entombed in a white marble sarcophagus beside the lake at Hogwarts, and it is said that he is the only headmaster to be buried on the school grounds.

text: Harry Potter and the Deathly Hallows

text: Rowling used several chapters in Harry Potter and the Deathly Hallows to reveal two main matters concerning Dumbledore: his early life and his death. The book introduces his parents, Percival and Kendra Dumbledore, as well as his little sister, Ariana; his brother, Aberforth Dumbledore, was mentioned in previous books. At six years old, Ariana was attacked by three Muggle boys who had witnessed her doing magic. Because of this attack, Ariana was seriously traumatised and never able to control her magic again, having recurring outbursts of magic. Enraged, Percival mercilessly attacked the Muggle boys (killing them in the film version), and was sentenced to life in Azkaban. After this, Kendra moved her family to the village of Godric's Hollow. In one of her outbursts, Ariana accidentally kills Kendra around the time Albus has completed his education. Albus becomes the head of the family and is forced to remain in his house with his sister Ariana while Aberforth completes his education.

text: Soon afterward, a young Gellert Grindelwald arrived in Godric's Hollow to live with his great-aunt, Bathilda Bagshot, author of A History of Magic. The two young men took to each other immediately, and together they dreamed of a world ruled by wizards over Muggles by uniting the legendary Deathly Hallows. They believed that if they were forced to destroy a few along the way, it would still be "for the greater good", and the sufferings and losses would be rewarded a hundredfold in the end. This scenario would never happen, though. A discussion between Albus, Aberforth, and Grindelwald led to a duel that resulted in Ariana's death. For the rest of his life, Albus felt guilty, never certain whether it was his own curse or another's that had killed his sister. Grindelwald stormed back to Bagshot's home and departed to begin his own rule, leaving the country hours later. As a result of his mistakes, Albus felt that he was not to be trusted with power and, because of this, never took the position of Minister for Magic, despite being offered it several times. Dumbledore returned to Hogwarts as professor of Transfiguration, and he served in recruiting students for the school.

text: Decades later, in 1945,[18] Dumbledore finally defeated the now-Dark wizard Grindelwald, who had come to possess the Elder Wand. Grindelwald's defeat made Dumbledore the master of the Elder Wand, which remained his until just before his death, when Draco used the Disarming Charm on him.

text: Dumbledore had another Hallow in his keeping since the death of James Potter: the Invisibility Cloak, which he had borrowed to examine. When James died, Dumbledore kept the cloak and decided to pass it on to Harry, James's son.

text: The truth about Dumbledore's death is revealed through Snape's last memories in the Pensieve. Harry learns that Dumbledore made a terrible error by placing a cursed ring on his right hand, sometime between the fifth and sixth book, forgetting the curses that must be on the ring. The ring held the Resurrection Stone, which Dumbledore hoped to use to allow him to apologise to his sister and parents. Dumbledore called Snape to help him; however, when Snape arrived and assessed the curse, all he could do was contain it. Snape told Dumbledore that he had little more than a year to live. After hearing this news, Dumbledore revealed to Snape that he knew about Voldemort's plan to have Draco kill him. He asked Snape to use the Killing Curse on him when the time came because he did not want Draco to have to kill him, saying that the boy's soul was still intact; Draco's soul would have been damaged in killing Dumbledore out of malice, whereas Snape was fully aware that he would be merely sparing Dumbledore pain and humiliation. He also intended for Snape to be the one to kill him and for the Elder Wand to be buried with him, in order to prevent the wand from being passed on again.

text: Dumbledore's spirit appears to Harry towards the end of the book in a limbo-like King's Cross, after Harry is struck with the Killing Curse which was conjured by Voldemort. During the last book, Harry finds out that he must die because he is a Horcrux. When Voldemort conjures the Killing Curse, Harry does not fight back, which stops him from dying. When they meet again, the boy comforts Dumbledore as he confesses all of his many regrets. Dumbledore then informs Harry of the choice he still has: of moving on to the next life or returning to his body to face Voldemort one last time. After returning from the mystical King's Cross and defeating Voldemort for good, Harry has a short conversation with Dumbledore's portrait in the Headmaster's office about the fate of each of the three Deathly Hallows. He keeps the Cloak, leaves the Stone in the Forbidden Forest where he dropped it, and returns the Elder Wand to Dumbledore's tomb (from which Voldemort had stolen it). In the epilogue, it is revealed that Harry names his second son Albus Severus Potter after Dumbledore and Snape.

text: Portrayals within films

text: In the film adaptations of Philosopher's Stone (2001) and Chamber of Secrets (2002), Dumbledore was played by Richard Harris, who was expected to play Dumbledore throughout the series. Harris mentioned that he was originally not going to take the role, since he knew his own health was in decline. He accepted because his then-11-year-old granddaughter threatened never to speak to him again if he did not take it.[19] Harris was determined to portray Dumbledore again in Prisoner of Azkaban (which was released in 2004), despite having been diagnosed with Hodgkin's lymphoma, and asked David Heyman not to recast the role.[20] However, his death on 25 October 2002 necessitated recasting.[21]

text: Ian McKellen was offered the role, but he turned it down, having played the similar character Gandalf in The Lord of the Rings trilogy, as well as feeling it would have been inappropriate to take Harris's role, as Harris had called McKellen a "dreadful" actor.[22] Harris's family had expressed an interest in seeing Peter O'Toole being chosen as his replacement.[23]

text: Michael Gambon was cast as Harris's replacement four months after Harris's death.[24] Gambon was not concerned about bettering Harris, and he portrayed the character in his own way, putting on a slight Irish accent for the role,[25] as well as completing his scenes in three weeks.[26] Gambon reprised his role in all the remaining films.

text: Toby Regbo was chosen to portray Dumbledore in his youth in Deathly Hallows Part I and Part 2, for flashbacks scenes which provide essential information on the character's backstory.[citation needed]

text: Jude Law was tapped to portray Dumbledore in the sequel to the first prequel film, Fantastic Beasts and Where to Find Them.[2]

text: In the Chamber of Secrets DVD interview, screenwriter Steve Kloves stated that he considers Dumbledore a fascinating character because of the wisdom he provides, but he feels that "Dumbledore bears such a tremendous dark burden, and he knows secrets and I think in many ways he bears the weight of the future of the wizard world" and the "only way that he can keep that at bay, the darkness, is to be whimsical and humorous".[7]

text: Characterisation

text: Appearance

text: Albus Dumbledore was tall and thin, with silver hair and beard (auburn in his youth) so long that they could be tucked into his belt. He had a very long and crooked nose that looked as if it had been broken at least twice. (It is speculated that his brother's punch during their sister's funeral may have played a role in shaping his nose.) He was also said to have had long and skillful fingers. His eyes were described to be a brilliant, soul-piercing shade of blue, and usually twinkled with kindness and mischief.

text: Dumbledore wore half-moon spectacles and a colourful array of robes, ranging from purple to bright orange. He once claimed to have a scar above his left knee in the precise shape of a map of the London Underground, but whether or not he actually does is unknown. His demeanour is often – if not always – serene and ethereal, and he usually spoke in a calm, pleasant voice even when Harry thought that he was actually furious.

text: During the last year of his life, Dumbledore's right hand was scarred when he donned Marvolo Gaunt's Ring, which was cursed. Had Snape not intervened with a counter-curse, Dumbledore would have died much more quickly. Regardless, the curse left his hand blackened and dead-looking, and no amount of healing could repair the appearance. According to Snape, the curse would eventually spread itself from the contained hand, and Dumbledore was doomed to die in no more than one year's time. Whether this means the blackening dead-look appearance would spread throughout the entire body is unknown.

text: Personality

text: Considered the most powerful wizard in the world, Dumbledore is benevolent and wise, a good wizard in the style of Merlin.[citation needed] He almost constantly gives off an aura of serenity and composure, rarely displaying intense emotions of anger or fear. Yet despite his benign nature, it is said that Dumbledore was the only wizard Lord Voldemort ever truly feared. Dumbledore is very eccentric and even slightly effeminate; he is very fond of knitting patterns and frequently wears flamboyant clothing (at one point, he is seen wearing a flowered bonnet). He is also known for his odd displays of whimsicality; he often uses humour to make people feel comfortable in his presence. As a supremely talented wizard, Dumbledore displays numerous examples of extraordinary powers. His abilities as a wizard are combined with a kind of cunning and subtlety of mind that allowed him to comprehend human nature and turn the better aspects of humanity (trust, love, and friendship) to Voldemort's disadvantage in particular.

text: More than anything else, Dumbledore has a deep capacity for love, frequently reminding Harry that love was the greatest magic of all. Dumbledore believes in the good in everyone and insists on giving second chances. The greatest example of this is Dumbledore's relationship with Snape, in whom Dumbledore is willing to place a considerable amount of faith because he showed remorse. Dumbledore is highly perceptive and emotionally intelligent; his knowledge of a person's true personality goes beyond simply being a good judge of character. This is never more apparent than in his complex insights into Voldemort's psyche, which he pieces together with Harry to deduce where Voldemort's horcruxes are hidden.

text: However, in spite of Dumbledore's many extraordinary qualities, he was no saint. According to Rowling, "Although Dumbledore seems to be so benign for six books, he's quite a Machiavellian figure, really. He's been pulling a lot of strings."[27] In a 2005 interview, Rowling commented: "Immense brainpower does not protect you from emotional mistakes, and I think Dumbledore really exemplifies that."[28] Dumbledore's greatest personality flaw, which he explained to Harry, was his desire for power. He eventually found that those best suited for power are those who do not seek it. When he and Grindelwald met each other, they made plans to enslave Muggles and re-establish wizards as the natural rulers of the world. However, Dumbledore was disillusioned of this fantasy after his sister Ariana was killed during a duel between himself, his brother Aberforth, and Grindelwald.

text: Dumbledore was haunted by his sad family history. In particular, he was riddled with guilt over the circumstances surrounding the death of his sister. He felt enormous remorse for his selfishness and was tortured for the rest of his life by the possibility that he might have been the one who cast the spell that killed his sister. When he looked into the Mirror of Erised, he saw himself redeemed in the eyes of his brother and his entire family alive and together.

text: Magical abilities and skills

text: Since a young age, Dumbledore has always shown great magical abilities. During his education at Hogwarts, Dumbledore was known as the most brilliant student to have ever stepped into the school, winning "every prize of note that the school offered", and in his N.E.W.T.s, "... did things with a wand [the examiner had] never seen before". Rowling has said that Dumbledore is primarily self-taught, although he "had access to superb teachers at Hogwarts," and, as far as his education is concerned, "Dumbledore's family would be a profitable line of inquiry."[29] While he is not vain, Dumbledore also exhibits no false modesty, readily acknowledging that he is unusually intelligent and an exceptionally powerful wizard. He admits a number of times to Harry in their occasional meetings in Half-Blood Prince that he makes mistakes, and since he is smarter than most men, his mistakes "tend to be correspondingly huger."

text: Dumbledore is an expert at nonverbal spells and is famous as an alchemist who has worked with Nicolas Flamel, the only known maker of the Philosopher's Stone, and is credited with discovering the twelve uses of dragon's blood. His Patronus takes the form of a phoenix,[30] a recurring symbol in the books.

text: His knowledge of the most powerful kind of magic, love, is extensive. He taught Harry about its very essence, and the innate power of his ability to love his parents, which eventually helped Harry realise his destiny to kill Lord Voldemort.

text: He is known to be able to conjure Gubraithian fire (magical everlasting fire). He has claimed to be able to become invisible without using an invisibility cloak, which is a powerful Disillusionment Charm. Dumbledore is also skilled in Occlumency and Legilimency. Dumbledore is an expert at Transfiguration too, having taught the subject before becoming headmaster. He frequently creates complex objects like sofa chairs out of thin air (or from less comfortable chairs). Dumbledore is also proficient at Charms and Potions; according to the obituary written by Elphias Doge, his papers were published in journals such as Achievements in Charming and The Practical Potioneer. Dumbledore is famous for defeating Grindelwald, who is second on a list of Most Dangerous Dark Wizards of All Time only to Voldemort himself, in a "spectacular duel of legend", succeeding in doing so despite the fact that Grindelwald possessed the Elder Wand, which supposedly guarantees invincibility in duels due to its power. His skill at duelling is further shown when he calmly engages Voldemort in Harry Potter and the Order of the Phoenix, overpowering him and eventually forcing him to possess Harry to be spared from total defeat. It is known in retrospect that Dumbledore possessed the Elder Wand when duelling Voldemort however, having taken it from Grindelwald. Unlike most wizards who make a distinct popping sound when they apparate Dumbledore notably is able to apparate silently; the only other wizard shown to possess this skill is Voldemort. Dumbledore is known to be able to understand Mermish and Gobbledegook (Goblin language) and Parseltongue.[31]

text: Possessions

text: Dumbledore's office houses "a number of curious [...] instruments." Among them is a Pensieve, a stone receptacle used to store and review memories, which witches and wizards are able to extract from their heads as a type of fluid. Harry first discovers this device in Goblet of Fire, and it is frequently used for flashback scenes throughout the remainder of the series. In the first chapter of Philosopher's Stone, Dumbledore is seen using the Deluminator, a device for removing and later returning light, and for use as a homing device. It is confirmed in Deathly Hallows when the object is inherited by Ron that the Deluminator is of Dumbledore's own design. Dumbledore is the possessor and master of the Elder Wand, an extremely powerful object known also as the "Wand of Destiny" or the "Deathstick", and one of the Deathly Hallows. Unlike many of the wand's previous owners, Dumbledore keeps its identity a closely guarded secret. He also has a pet phoenix named Fawkes. It is revealed in Philosopher's Stone by Mr. Ollivander that Harry's wand carries a phoenix feather as its magical core and that particular phoenix only gave one other feather, the one in Voldemort's wand that gave Harry his scar. It is later revealed in Goblet of Fire that Fawkes was the phoenix whose feathers provide the magical core in Harry's and Voldemort's wands.

text: Family

text: Through various interviews and discussions about the character, Rowling has established that Albus Dumbledore was born in July or August[32][33] 1881[34] to Percival and Kendra Dumbledore.[12] The character had previously referenced his brother Aberforth, and in Harry Potter and the Deathly Hallows, it is revealed that Albus is three years older than Aberforth. The same book established their sister Ariana who, at six years old, suffered a vicious attack by three male Muggle youths who had witnessed her doing magic. Frightened, they first tried to get her to repeat what they had seen, and upon her failure to recreate it due to her young age, they tried to stop her from being "different". It is not explicitly stated in the novel what form this attack took, but Percival was sentenced to life in Azkaban for tracking down and hexing the boys who seriously traumatised his daughter. The severe trauma of the attack left Ariana unable to function socially or to properly perform magic again. To prevent her being institutionalised in St. Mungo's Hospital, or hurting someone accidentally with her uncontrolled magic, Kendra moved the family to Godric's Hollow, and her illness was concealed. Neighbours assumed that Ariana was a non-magical squib.

text: When Dumbledore and his friend Elphias left Hogwarts, they planned to take their "then-traditional" tour of the world. On the eve of their trip, the eighteen-year-old Dumbledore suffered the death of his mother Kendra, who was accidentally killed by Ariana during one of her uncontrolled outbursts of magic. Because Dumbledore's parents were absent (his father in Azkaban and his mother dead), Albus became the head of the family and it became his duty to put food on the table, as they were not left with much gold. He was forced to remain in his house with his sister Ariana while Aberforth completed his education. Aberforth knew of his brother's resentment and offered to care for Ariana himself, saying that she preferred him, but Albus refused by stating that it was his duty as eldest to care for the family.

text: When Grindelwald arrived at Godric's Hollow, he immediately became friends with Dumbledore and together dreamed of a new world order in which wizards ruled over Muggles "for the greater good". Dumbledore and Grindelwald suggested that they had to move to carry on their plans, but Aberforth refused because Ariana's state did not allow her to be moved. The discussion between Albus, Aberforth and Grindelwald turned into a duel that resulted in Ariana's accidental death. According to the author, as a result of this incident, Albus's boggart became Ariana's corpse.[35] In Philosopher's Stone, he mentions to Harry that the deepest desire of his heart, revealed by the Mirror of Erised, is to have a pair of woollen socks. In the seventh novel, Harry realises that he and Dumbledore see the same thing in the Mirror: their reunited families.

text: Reception

text: The character of Albus Dumbledore has been compared to other archetypal "wise old man" characters. Dumbledore acts much like Merlin from The Sword in the Stone, in the manner of an "absent-minded professor";[36] both Merlin and Dumbledore educate a story's main character in a castle. As writer Evelyn Perry notes, "Dumbledore resembles Merlin both personally and physically; he is an avid lover of books and wisdom who wears flowing robes and a long, white beard."[37] Dumbledore has also been compared with Gandalf from Tolkien's Lord of the Rings.[38] Dave Kopel draws comparisons between Rowling's writing and John Bunyan's The Pilgrim’s Progress and states that, among the Christian symbols that Rowling has used in her books, Dumbledore acts like "the bearded God the Father" figure in which Harry puts his faith to be saved from Voldemort and his servants.[39] IGN also listed Dumbledore as their fifth favourite Harry Potter character, saying that "[f]or a character that was introduced into popular culture a mere twelve years ago, it speaks volumes that Professor Dumbledore has already taken his place among the great mentor figures in literature and film".[40] IGN's Joe Utichi called Dumbledore his third favourite Harry Potter character, calling the revelation that he wasn't so "infallible" one of the most heartbreaking themes of the final book.[41] Actor Michael Gambon received some criticism for his louder, more aggressive, portrayal of the character, who is depicted as exhibiting a more subdued, unflappable calm in the books. This has been attributed to Gambon's policy of not reading the source material from which his films are adapted.[42]

text: As a main character of the series, major facts relating to Dumbledore have generated a vast number of essays and discussions. The death of Dumbledore at the end of Half-Blood Prince was discussed by fans and critics alike. A website named DumbledoreIsNotDead.com sought to understand the events of the sixth book in a different way and provided arguments to claim that the character did not really die.[43] However, Rowling confirmed on 2 August 2006 that Dumbledore was, in fact, dead, humorously apologising to the website as she did so.[44] Along with DumbledoreIsNotDead.com, a collection of essays, Who Killed Albus Dumbledore?: What Really Happened in Harry Potter and the Half-Blood Prince? Six Expert Harry Potter Detectives Examine the Evidence, was published by Zossima Press in November 2006.[45] In NextMovie.com's Harry Potter Mega Poll, Dumbledore's death was voted as the most unforgettable moment in the whole series.[46]

text: Sexuality

text: Rowling's statement that Dumbledore was gay caused a great debate among critics. Melissa Anelli, webmaster of the fan site The Leaky Cauldron, told The Associated Press, "J.K. Rowling calling any Harry Potter character gay would make wonderful strides in tolerance toward homosexuality. ... By dubbing someone so respected, so talented and so kind, as someone who just happens to be also homosexual, she's reinforcing the idea that a person's gayness is not something of which they should be ashamed."[47] Entertainment Weekly's Mark Harris said "her choice to make a beloved professor-mentor gay in a world where gay teachers are still routinely slandered as malign influences was, I am certain, no accident."[48] The stars and director of the Harry Potter films were supportive of Rowling's revelation as well.[49]

text: Some critics discussed the implications of this statement. New York Times columnist Edward Rothstein said that "Ms. Rowling may think of Dumbledore as gay"; however, "there is no reason why anyone else should".[50] The East Tennessee State University's student newspaper accused Rowling of lying, saying her answer was a publicity stunt.[51] Michelle Smith quoted the Death of the Author principle, stating that Rowling's subsequent commentary is irrelevant to the understanding of the books.[52]

text: Dumbledore's sexuality was also condemned by several right-wing Christian groups, such as Mission America and the Christian Coalition of America.[53]

text: Slate quotes an attendee of the book talk who said, "It was clear that JKR didn't plan to out Dumbledore. She just cares about being true to her readers."[54] Mike Thomas of the Orlando Sentinel said that upon reflection, Dumbledore was gay from the beginning, and that this neatly explains the behaviour of his character and his relationship with Grindelwald. Thomas notes the skill Rowling displays in writing a gay character without having to put a gay label on him.[55]

text: Gay rights campaigner Peter Tatchell stated that "It's good that children's literature includes the reality of gay people, since we exist in every society. But I am disappointed that she did not make Dumbledore's sexuality explicit in the Harry Potter book. Making it obvious would have sent a much more powerful message of understanding and acceptance." A spokesperson for Stonewall praised Rowling, saying "It's great that JK has said this. It shows that there's no limit to what gay and lesbian people can do, even being a wizard headmaster."[56]

text: In popular culture

text: Dumbledore has been parodied in several sketches and animated series:

text:
In the series Wizards of Waverly Place, the episodes "Wizard School Part 1" and "Wizard School Part 2" feature Alex and Justin Russo going to a wizarding summer school called Wiz-tech, in which Headmaster Crumbs (played by Ian Abercrombie) is based on Dumbledore.[citation needed]
In The Simpsons episode "The Haw-Hawed Couple", Lisa asks Homer to read her Angelica Button book to her for bedtime. Homer, learning that the character Headmaster Greystash will die (as Dumbledore did in Half-Blood Prince), hides the fact from Lisa by inventing a happier ending, though Lisa does read the real ending and decides that Homer's was better.[57]
Dumbledore also stars in Neil Cicierega's Potter Puppet Pals, in which he frequently strips completely naked, except for his hat, randomly in the story. Also, in half of the "Potter Puppet Pals" videos Dumbledore is using the exclamation "Alas!" in an apparently incorrect place, parodying Rowling's love for unusual words. In the episode "Ron's Disease", Dumbledore reveals himself to be "a gay android".[58]
Albus Dumbledore appears in some episodes of Robot Chicken voiced by Seth Green. In "Password: Swordfish" when the threat of the puberty creature Pubertis is known, Dumbledore gives Harry a stone that might help him fight Pubertis. During this appearance, Dumbledore is an African-American who states that he is played by a different actor in each of the movies. Upon confrontation with Pubertis, Harry rubs the stone two times, which summons ghosts to punch it. When it comes to the third time, Dumbledore appears and tells Harry that the stone can only be warmed up three times a day (four if he takes a week off) and that Pubertis cannot be destroyed since it lives in everyone just like his own demon Wandus Limpus prevents him from having meaningful relationships. In "Tell My Mum", Dumbledore tells the students that Professor Snape suffered a "minor potion accident" and has enlisted Criss Angel as their substitute teacher.
In 2003, Comic Relief performed a spoof story called Harry Potter and the Secret Chamberpot of Azerbaijan, in which Dumbledore is portrayed by Nigel Planer, who wore the beard and costume of late Richard Harris.[59][60]
Dumbledore also appears in one of the Harry Bladder sketches in All That, portrayed by Kenan Thompson's old character Principal Williame Banes Pimpell (who appeared as Headmaster Pimpell).
After the revelation of Dumbledore's sexuality, the American skit comedy Saturday Night Live featured a sketch featuring Rowling (played by Amy Poehler) showing deleted scenes from Harry Potter and the Prisoner of Azkaban where Dumbledore (played by Bill Hader) acts stereotypically gay.[61]
In A Very Potter Musical, Dumbledore is played by actor Dylan Saunders.
Dumbledore appears in an episode of Icons of Teen from the YouTube channel, Shut Up Cartoons voiced by Justin Roiland. As a teenager, Dumbledore liked to do magic and make robotic copies of himself. One day, he went scuba diving to earn his scuba diving badge for scouts. Dumbledore gets scared and stays on the boat while his crush Charlene and the scoutmaster go diving. They run into a giant sea monster and Charlene closes her eyes and says Dumbledore, a trick he taught her. Dumbledore receives her distress signal and dives in after them. He meets a talking dolphin who agrees to help Dumbledore if he can eat him in the end. Dumbledore suggests he eat the scoutmaster and the dolphin takes him to his friends. Dumbledore makes a robotic copy and sends it into the creature's stomach, distracting the creature long enough for Dumbledore, Charlene and the scoutmaster to escape. Charlene thanks Dumbledore for saving them. Dumbledore makes a sexual comment but plays it off like she said it. Charlene asks where the scoutmaster is; Dumbledore says he's gone somewhere, when really the dolphin ate him. Dumbledore then decides to build a robot copy of the scoutmaster to prevent anyone from finding out what happened to him.
Albus Dumbledore appears in The Lego Movie, though his voice actor is not credited. He is seen among the Master Builders who meet with Vitruvius in Cloud Cuckoo Land, including a Lego version of Gandalf from The Lord of the Rings.


document_title: Leopard (pattern)

question_text: what is the pattern on a leopard's coat called

question_tokens: what is the pattern on a leopard 's coat called

text: Leopard (pattern)

text: This article does not cite any sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (February 2007) (Learn how and when to remove this template message)

tag: table

text: A leopard pattern is a spotted color pattern, particularly in the hair coat or skin of animals, but can also describe spotting patterns in plants and fabrics. The term refers to the black and gold spotted coat of the leopard cat, but is used to describe many color combinations that result in spots scattered randomly across the skin or hair coat of other animals. Examples of animals with coloring patterns termed leopard include many great cats in the genus Panthera, the leopard frog, the "leopard" spotting pattern in the Appaloosa and Knabstrupper breeds of horses, the leopard seal, insects such as the giant leopard moth, and fish species such as the leopard darter, leopard shark, and the leopard eel. Examples of plants that use the term include the leopard lily, and the leopard flower.

text: The Lp (leopard complex) gene is responsible for the leopard color pattern in horses, which not only produces a spotted coat color but also causes mottling of the skin, a white sclera around the eye, and striped hooves. Horses with the Lp gene may be spotted all over, or may have concentrations of spots in various patterns.

text: Horse coat colors

text: Articles lacking sources from February 2007All articles lacking sources


document_title: Bessemer process

question_text: who invented the process to remove impurities by blasts of cold air blown through heated iron

text: Bessemer process

text: History[edit]

text: Early history[edit]

text: A system akin to the Bessemer process has existed since the 11th century in East Asia.[2][3] Economic historian Robert Hartwell writes that the Chinese of the Song Dynasty innovated a "partial decarbonization" method of repeated forging of cast iron under a cold blast.[11] Sinologist Joseph Needham and historian of metallurgy Theodore A. Wertime have described the method as a predecessor to the Bessemer process of making steel.[2][12][13] This process was first described by the prolific scholar and polymath government official Shen Kuo (1031–1095) in 1075, when he visited Cizhou.[11] Hartwell states that perhaps the earliest center where this was practiced was the great iron-production district along the Henan–Hebei border during the 11th century.[11]

text: In the 15th century the finery process, another process which shares the air-blowing principle with the Bessemer process, was developed in Europe. In 1740 Benjamin Huntsman developed the crucible technique for steel manufacture, at his workshop in the district of Handsworth in Sheffield. This process had an enormous impact on the quantity and quality of steel production, but it was unrelated to the Bessemer-type process employing decarburization.

text: The Japanese may have made use of a Bessemer-type process, which was observed by European travelers in the 17th century.[4] The adventurer Johan Albrecht de Mandelslo describes the process in a book published in English in 1669. He writes, "They have, among others, particular invention for the melting of iron, without the using of fire, casting it into a tun done about on the inside without about half a foot of earth, where they keep it with continual blowing, take it out by ladles full, to give it what form they please." According to historian Donald Wagner, Madelslo did not personally visit Japan, so his description of the process is likely derived from accounts of other Europeans who had traveled to Japan. Wagner believes that the Japanese process may have been similar to the Bessemer process, but cautions that alternative explanations are also plausible.[4]

text: Bessemer's patent[edit]

text: In the early 1850s, the American inventor William Kelly experimented with a method similar to the Bessemer process. Wagner writes that Kelly may have been inspired by techniques introduced by Chinese ironworkers hired by Kelly in 1854.[4] When Bessemer's patent for the process was reported by Scientific American, Kelly responded by writing a letter to the magazine. In the letter, Kelly states that he had previously experimented with the process and claimed that Bessemer knew of Kelly's discovery. He wrote that "I have reason to believe my discovery was known in England three or four years ago, as a number of English puddlers visited this place to see my new process. Several of them have since returned to England and may have spoken of my invention there."[4]

text: Sir Henry Bessemer described the origin of his invention in his autobiography written in 1890. During the outbreak of the Crimean War, many English industrialists and inventors became interested in military technology. According to Bessemer, his invention was inspired by a conversation with Napoleon III in 1854 pertaining to the steel required for better artillery. Bessemer claimed that it "was the spark which kindled one of the greatest revolutions that the present century had to record, for during my solitary ride in a cab that night from Vincennes to Paris, I made up my mind to try what I could to improve the quality of iron in the manufacture of guns."[5] At the time steel was used to make only small items like cutlery and tools, but was too expensive for cannons. Starting in January 1855 he began working on a way to produce steel in the massive quantities required for artillery and by October he filed his first patent related to the Bessemer process. He patented the method a year later in 1856.[5]

text: Bessemer licensed the patent for his process to four ironmasters, for a total of £27,000, but the licensees failed to produce the quality of steel he had promised—it was "rotten hot and rotten cold", according to his friend, William Clay[14]—and he later bought them back for £32,500.[15] His plan had been to offer the licenses to one company in each of several geographic areas, at a royalty price per ton that included a lower rate on a proportion of their output in order to encourage production, but not so large a proportion that they might decide to reduce their selling prices. By this method he hoped to cause the new process to gain in standing and market share.[14]

text: He realised that the technical problem was due to impurities in the iron and concluded that the solution lay in knowing when to turn off the flow of air in his process so that the impurities were burned off but just the right amount of carbon remained. However, despite spending tens of thousands of pounds on experiments, he could not find the answer.[16] Certain grades of steel are sensitive to the 78% nitrogen which was part of the air blast passing through the steel.

text: Bessemer was sued by the patent purchasers who couldn't get it to work. In the end Bessemer set up his own steel company because he knew how to do it, even though he could not convey it to his patent users. Bessemer's company became one of the largest in the world and changed the face of steel making.[17]

text: The solution was first discovered by English metallurgist Robert Forester Mushet, who had carried out thousands of experiments in the Forest of Dean. His method was to first burn off, as far as possible, all the impurities and carbon, then reintroduce carbon and manganese by adding an exact amount of spiegeleisen. This had the effect of improving the quality of the finished product, increasing its malleability—its ability to withstand rolling and forging at high temperatures and making it more suitable for a vast array of uses.[18][19] Mushet's patent ultimately lapsed due to Mushet's inability to pay the patent fees and was acquired by Bessemer. Bessemer earned over 5 million dollars in royalties from the patents.[20]

text: The first company to license the process was the Manchester firm of W & J Galloway, and they did so before Bessemer announced it at Cheltenham in 1856. They are not included in his list of the four to whom he refunded the license fees. However, they subsequently rescinded their license in 1858 in return for the opportunity to invest in a partnership with Bessemer and others. This partnership began to manufacture steel in Sheffield from 1858, initially using imported charcoal pig iron from Sweden. This was the first commercial production.[14][21]

text: Industrial revolution in the United States[edit]

text: Alexander Lyman Holley contributed significantly to the success of Bessemer steel in the United States. His A Treatise on Ordnance and Armor is an important work on contemporary weapons manufacturing and steel-making practices. In 1862, he visited Bessemer's Sheffield works, and became interested in licensing the process for use in the US. Upon returning to the US, Holley met with two iron producers from Troy, New York, John F. Winslow and John Augustus Griswold, who asked him to return to the United Kingdom and negotiate with the Bank of England on their behalf. Holley secured a license for Griswold and Winslow to use Bessemer's patented processes and returned to the United States in late 1863.[22]

text: The trio began setting up a mill in Troy, New York in 1865. The factory contained a number of Holley's innovations that greatly improved productivity over Bessemer's factory in Sheffield, and the owners gave a successful public exhibition in 1867. The Troy factory attracted the attention of the Pennsylvania Railroad, which wanted to use the new process to manufacture steel rail. It funded Holley's second mill as part of its Pennsylvania Steel subsidiary. Between 1866 and 1877, the partners were able to license a total of 11 Bessemer steel mills.

text: One of the investors they attracted was Andrew Carnegie, who saw great promise in the new steel technology after a visit to Bessemer in 1872, and saw it as a useful adjunct to his existing businesses, the Keystone Bridge Company and the Union Iron Works. Holley built the new steel mill for Carnegie, and continued to improve and refine the process. The new mill, known as the Edgar Thomson Steel Works, opened in 1875, and started the growth of the United States as a major world steel producer.[23] Using the Bessemer process, Carnegie Steel was able to reduce the costs of steel railroad rails from $100 per ton to $50 per ton between 1873 and 1875. The price of steel continued to fall until Carnegie was selling rails for $18 per ton by the 1890s. Prior to the opening of Carnegie's Thomson Works]], steel output in the United States totaled around 157,000 tons per year. By 1910, American companies were producing 26 million tons of steel annually.[24]

text: William Walker Scranton, manager and owner of the Lackawanna Iron & Coal Company in Scranton, Pennsylvania, had also investigated the process in Europe. He built a mill in 1876 using the Bessemer process for steel rails and quadrupled his production.[25]

text: Bessemer steel was primarily used in the United States for railroad rails. During the construction of the Brooklyn Bridge, a major dispute arose over whether crucible steel should be used instead of the cheaper Bessemer steel. In 1877, Abram Hewitt wrote a letter urging against the use of Bessemer steel in the construction of the Brooklyn Bridge.[26][27] Bids had been submitted for both crucible steel and Bessemer steel; John A. Roebling's Sons submitted the lowest bid for Bessemer steel,[28] but at Hewitt's direction, the contract was awarded to J. Lloyd Haigh Co..[29]

text: Technical details[edit]

text: Using the Bessemer process, it took between 10 and 20 minutes to convert three to five tons of iron into steel — it used to take at least a full day of heating, stirring and reheating to achieve this.[30]

text: Oxidation[edit]

text: The blowing of air through the molten pig iron introduces oxygen into the melt which results in oxidation, removing impurities found in the pig iron, such as silicon, manganese, and carbon in the form of oxides. These oxides either escape as gas or form a solid slag. The refractory lining of the converter also plays a role in the conversion — clay linings are used when there is little phosphorus in the raw material – this is known as the acid Bessemer process. When the phosphorus content is high, dolomite, or sometimes magnesite, linings are used in the alkaline Bessemer limestone process. These are also known as Gilchrist–Thomas converters, after their inventors, Percy Gilchrist and Sidney Gilchrist Thomas. In order to produce steel with desired properties, additives such as spiegeleisen (a ferromanganese alloy), can be added to the molten steel once the impurities have been removed.

text: Managing the process[edit]

text: When the required steel had been formed, it was poured into ladles and then transferred into moulds while the lighter slag was left behind. The conversion process, called the "blow", was completed in approximately 20 minutes. During this period the progress of the oxidation of the impurities was judged by the appearance of the flame issuing from the mouth of the converter. The modern use of photoelectric methods of recording the characteristics of the flame greatly aided the blower in controlling final product quality. After the blow, the liquid metal was recarburized to the desired point and other alloying materials were added, depending on the desired product.

text: A Bessemer converter could treat a "heat" (batch of hot metal) of 5 to 30 tons at a time.[31] They were usually operated in pairs, one being blown while another was being filled or tapped.

text: Predecessor processes[edit]

text: Before the Bessemer process, steel could only be made from wrought iron. Wrought iron was made by reducing the carbon content of pig iron. The traditional way to remove carbon from pig iron was to heat the pig iron directly in a fire and hit it with a hammer. This method was extremely labor intensive and by the early 19th century it had been replaced by the puddling process. Until technological advances made it possible to work at higher heats, slag impurities could not be removed entirely, but the reverberatory furnace made it possible to heat iron without placing it directly in the fire, offering some degree of protection from the impurity of the fuel source. Thus, with the advent of this technology, coal began to replace charcoal fuel. The Bessemer process allowed steel to be produced without fuel, using the impurities of the iron to create the necessary heat. This drastically reduced the costs of steel production, but raw materials with the required characteristics could be difficult to find.[32]

text: High-quality steel was made by the reverse process of adding carbon to carbon-free wrought iron, usually imported from Sweden. The manufacturing process, called the cementation process, consisted of heating bars of wrought iron together with charcoal for periods of up to a week in a long stone box. This produced blister steel. The blister steel was put in a crucible with wrought iron and melted, producing crucible steel. Up to 3 tons of expensive coke was burnt for each ton of steel produced. Such steel when rolled into bars was sold at £50 to £60 (approximately £3,390 to £4,070 in 2008)[33] a long ton. The most difficult and work-intensive part of the process, however, was the production of wrought iron done in finery forges in Sweden.

text: This process was refined in the 18th century with the introduction of Benjamin Huntsman's crucible steel-making techniques, which added an additional three hours firing time and required additional large quantities of coke. In making crucible steel, the blister steel bars were broken into pieces and melted in small crucibles, each containing 20 kg or so. This produced higher quality crucible steel but increased the cost. The Bessemer process reduced the time needed to make steel of this quality to about half an hour while requiring only the coke needed initially to melt the pig iron. The earliest Bessemer converters produced steel for £7 a long ton, although it initially sold for around £40 a ton.

text: "Basic" vs. acidic Bessemer process[edit]

text: Sidney Gilchrist Thomas, a Londoner with a Welsh father, was an industrial chemist who decided to tackle the problem of phosphorus in iron, which resulted in the production of low grade steel. Believing that he had discovered a solution, he contacted his cousin, Percy Gilchrist, who was a chemist at the Blaenavon ironworks. The manager at the time, Edward Martin, offered Sidney equipment for large-scale testing and helped him draw up a patent that was taken out in May, 1878. Sidney Gilchrist Thomas's invention consisted of using dolomite or sometimes limestone linings for the Bessemer converter rather than clay, and it became known as the 'basic' Bessemer rather than the 'acid' Bessemer process. An additional advantage was that the processes formed more slag in the converter, and this could be recovered and used very profitably as a phosphate fertilizer.[34]

text: Importance[edit]

text: In 1898, Scientific American published an article called Bessemer Steel and its Effect on the World explaining the significant economic effects of the increased supply in cheap steel. They noted that the expansion of railroads into previously sparsely inhabited regions of the country had led to settlement in those regions, and had made the trade of certain goods profitable, which had previously been too costly to transport.[35]

text: The Bessemer process revolutionized steel manufacture by decreasing its cost, from £40 per long ton to £6–7 per long ton, along with greatly increasing the scale and speed of production of this vital raw material. The process also decreased the labor requirements for steel-making. Before it was introduced, steel was far too expensive to make bridges or the framework for buildings and thus wrought iron had been used throughout the Industrial Revolution. After the introduction of the Bessemer process, steel and wrought iron became similarly priced, and some users, primarily railroads, turned to steel. Quality problems, such as brittleness caused by nitrogen in the blowing air,[36] prevented Bessemer steel from being used for many structural applications.[37] Open-hearth steel was suitable for structural applications.

text: Steel greatly improved the productivity of railroads. Steel rails lasted ten times longer than iron rails. Steel rails, which became heavier as prices fell, could carry heavier locomotives, which could pull longer trains.[38] Steel rail cars were longer and were able to increase the freight to car weight from 1:1 to 2:1.

text: As early as 1895 in the UK it was being noted that the heyday of the Bessemer process was over and that the open hearth method predominated. The Iron and Coal Trades Review said that it was "in a semi-moribund condition. Year after year, it has not only ceased to make progress, but it has absolutely declined." It has been suggested, both at that time and more recently, that the cause of this was the lack of trained personnel and investment in technology rather than anything intrinsic to the process itself.[39] For example, one of the major causes of the decline of the giant ironmaking company Bolckow Vaughan of Middlesbrough was its failure to upgrade its technology.[40] The basic process, the Thomas-Gilchrist process, remained in use longer, especially in Continental Europe, where iron ores were of high phosphorus content[41] and the open-hearth process was not able to remove all phosphorus; almost all inexpensive construction steel in Germany was produced with this method in the 1950s and 1960s.[42] It was eventually superseded by basic oxygen steelmaking.

text: Obsolescence[edit]

text: In the U.S., commercial steel production using this method stopped in 1968. It was replaced by processes such as the basic oxygen (Linz–Donawitz) process, which offered better control of final chemistry. The Bessemer process was so fast (10–20 minutes for a heat) that it allowed little time for chemical analysis or adjustment of the alloying elements in the steel. Bessemer converters did not remove phosphorus efficiently from the molten steel; as low-phosphorus ores became more expensive, conversion costs increased. The process permitted only limited amount of scrap steel to be charged, further increasing costs, especially when scrap was inexpensive. Use of electric arc furnace technology competed favourably with the Bessemer process resulting in its obsolescence.

text: Basic oxygen steelmaking is essentially an improved version of the Bessemer process (decarburization by blowing oxygen as gas into the heat rather than burning the excess carbon away by adding oxygen carrying substances into the heat). The advantages of pure oxygen blast over air blast was known to Henry Bessemer,[citation needed] but the 19th-century technology was not advanced enough to allow for the production of the large quantities of pure oxygen to make it economically feasible for use.