I used to be the Webmaster of a now defunct Website called The Alkan Site. One of the more worthwile pages on my site addressed the controversy behind Alkan's death. I emailed a conductor by the name of Mark Starr who kindly provided a detailed answer to the question. The following is the excerpt from my page:
The mystery of Alkan's death was resolved definitively about a decade ago by the French Societé Alkan. A French musicologist (possibly Brigitte Sappey) discovered a long detailed letter by one of Alkan's female piano students, who arrived at Alkan's teaching studio for her lesson just hours after Alkan had expired. In the letter she elaborates that Alkan did indeed fall and injure himself while he was trying to retrieve something on a shelf. He had climbed up on a hall coat-and-hat stand - a typical, large fixture in many 19th Century French homes. Alkan lost his balance and fell - and books did fall on top of him (the student's letter makes no mention of the Talmud). However, it was the fall and not the books that severely injured him.
Alkan did not die right away. A doctor was sent for, arrived, and began treating Alkan's injuries. But as the final portrait of Alkan makes clear, by 1888 he was a very frail, old man. He eventually succumbed to his injuries and died several hours later.
The gothic detail of Alkan having been crushed by his copy of the Talmud appears to be a colorful invention of one of the pianists in Alkan's small circle of friends, probably Isidor Philip. In poor health in his final years, Alkan already knew his days were numbered. In the few months preceding his death, he got all his affairs in order -- including the making of an incredibly detailed will. He also had his manuscripts bound in leather (these invaluable documents have disappeared, never yet to surface.)
The amusing detail about the Talmud is apocryphal. Instead of complaining about the fabrication of this detail, it is better to be grateful to whoever made it up. Limited as Alkan's fame has been in the past, this is the one factoid that has spread his renown among the general public and even among musicians. The more interest in Alkan, and the more people that remember his name (and listen to his music), the better. - Mark Starr