is a book that can be found in the Witch's House on the table in the Kitchen
, which serves as a clue for the poison puzzle.
The book hints that you have to put the Silver Key into the bowl of poisonus soup in order to proceed.
People of ruling and wealthy classes have long enjoyed dining with silverware.
Using such hard-to-clean cutlery proved they were wealthy enough to hire servants.
In addition, silver utensils change color upon contact with poison, making them quite useful.