One or two of those powders introduced into the full bottle of medicine would effectually precipitate the strychnine, as the book describes, and cause it to be taken in the last dose. 
Two powders were put into the medicine bottle.
mnli hypothesis: Two powders were put into the medicine bottle. premise: One or two of those powders introduced into the full bottle of medicine would effectually precipitate the strychnine, as the book describes, and cause it to be taken in the last dose. 