Quote 4
If I don't sleep at once, chloral, the modern Morpheus—C2HCl3O.H2O! I should be careful not to let it grow into a habit. No I shall take none tonight! I have thought of Lucy, and I shall not dishonor her by mixing the two. (8.35)
Chloral, or chloral hydrate, is a sedative that was originally used to treat insomnia, and sometimes used as an anesthetic. It's only mildly addictive, but it was still abused and misprescribed a lot in the late 19th century. Nowadays it's illegal in the US without a prescription. In the late 19th century, though, it wasn't a controlled substance, and doctors, like Jack Seward, could just dose themselves if they had trouble sleeping. No wonder addiction was so common!