From observation during a period of nearly fifty years as a practical Chemist and Manufacturer of Chemical Products and all kinds of Oils, and my close connection with Engineers and Manufacturers, and experience with the endless varieties of Engines and Machinery in use, I have long felt the need of some work that would collectively treat in a condensed and comprehensive form the subjects of Friction, Lubrication, the origin and characteristics of Fats and Oils, their Uses, their Adulterations and their Practical Testing, all of such vital importance in the mechanical world.

In the effort to produce a book to fill these wants and make it useful as well as easily understood by Mechanics and Manufacturers not very familiar with these subjects, I have throughout avoided as much as possible all scientific technology, as well as technical terms and theories familiar only to the experienced chemist, and have endeavored to write in such language and manner as can be readily comprehended by anybody with an ordinary school education.

I would here take occasion to acknowledge the endorsement given to my former writings and to my lectures on these subjects, and to the generous patronage extended to my "valve-oleum" lubricating oils.

My theories on lubrication, which led to the production of the "valve-oleum" oils, at first met with much derision. But notwithstanding the fact that I have made many efforts to arouse, by my publications and lectures, more attention to, and to elicit information upon, the subject, thus far no sound argument has been advanced to refute these theories or to uphold those other ones, older and long persistently held.

Should I have been successful in producing such a treatise as will meet the demands of the time - and with this faith, I hereby dedicate this volume to manufacturers, and mechanics, and to my brother engineers of the National Association of Stationery Engineers of America - I shall feel myself amply repaid for my labor.

As is the practice of the publishers, the book has been supplied with a full table of contents and a thorough index, rendering reference to any subject in it prompt and accurate.

E. F. Dieterichs. Cleveland, Ohio, September 15, 1906.