In compiling this book of formulas, recipes and processes, the Editor has endeavored to meet the practical requirements of the home and workshop—the mechanic, the manufacturer, the artisan, the housewife, and the general home worker.

In addition to exercising the utmost care in selecting his materials from competent sources, the Editor has also modified formulas which were obviously ill adapted for his needs, but were valuable if altered. Processes of questionable merit he has discarded. By adhering to this plan the Editor trusts that he has succeeded in preparing a repository of useful knowledge representing the experience of experts in every branch of practical achievement. Much of the matter has been specially translated for this work from foreign technological periodicals and books. In this way the Editor has embodied much practical information otherwise inaccessible to most English-speaking people.

Each recipe is to be regarded as a basis of experiment, to be modified to suit the particular purpose in hand, or the peculiar conditions which may affect the experimenter. Chemicals are not always of uniform relative purity and strength; heat or cold may markedly influence the result obtained, and lack of skill in the handling of utensils and instruments may sometimes cause failure. Inasmuch as a particular formula may not always be applicable, the Editor has thought it advisable to give as many recipes as his space would allow under each heading. In some instances a series of formulas is given which apparently differ but slightly in their ingredients. This has been done on the principle that one or more may be chosen for the purpose in hand.

Recognizing the fact that works of a similar character are not unknown, the Editor has endeavored to present in these pages the most modern methods and formulas. Naturally, old recipes and so-called trade secrets which have proven their value by long use are also included, particularly where no noteworthy advance has been made; but the primary aim has been to modernize and bring the entire work up to the present date.

THE EDITOR. April, 1921.