It would not be very difficult to do so.

Then he remembered that among his books was one that probably contained some information about this subject.

He went over to the book-shelf and presently found the volume; it was called The Cyclopedia of Practical Medicine, rather an old book, a little out of date, perhaps, but still it might contain the information he wanted.

Opening it, he turned to the table of contents.

Many different subjects were mentioned there and presently he found the one he sought: Poisons: chemically, physiologically and pathologically considered.
Corrosive Poisons.
Narcotic Poisons.
Slow Poisons.
Consecutive Poisons.
Accumulative Poisons.
He turned to the chapter indicated and, reading it, he was astonished to find what a number of poisons there were within easy reach of whoever wished to make use of them: poisons that could be relied upon to do their work certainly, quickly and without pain.