Excerpt from Introduction to Chemical Preparations: A Guide in the Practical Teaching of Inorganic Chemistry In the choice of the preparations, care was taken to present to the student many fundamentally differ ent reactions. The author trusts to have done justice to the economy of the laboratory by starting, as far as possible, with cheap or valueless materials; for example, the residues of all sorts accumulated in every laboratory, or the by-products from other prepara tions. The finished preparations are, on the other hand, for the most part substances which are con tinually used in the laboratory in analytical and syn thetical processes, but which are either not generally found in the market or else not obtainable in a suf ficiently pure state.