Furthermore, Thurston[31] states that "all vegetable and animal oils are compounds of glycerine and the fatty acids. When they become old decomposition takes place, and acid is set free, by which action, as is commonly said, the oils become rancid." Thus Saunier is borne out in his admonition. ~89. In Conclusion~, the author wishes to state, that as he has been able to find but little in the literature of the craft in English, French or German, he has pursued the study of the "properties and relative values of lubricants in horology" upon lines which have suggested themselves as being best adapted to give good results. As much that is herein contained is new and original in its application in horology, the theories advanced may be in some respects incorrect. The tests of various oils have, no doubt, been subject to personal error; but it has been the earnest desire of the author to give the subject the attention it deserves. In order that truth may prevail and that justice may be done to the various manufacturers of oils, as well as to the author and his subject, he will again request criticism through the trade press in any matter in which he may seem to be at fault. He further wishes that others may become interested, and that the makers and repairers of watches, chronometers and clocks, as well as the manufacturers of oil, will further assist in these investigations by making similar or other experiments, and report the result of the same through the trade press in order that this very important subject may be thoroughly understood. In furtherance of this object the author will furnish samples of oils _free_ to anyone wishing to make experimental tests of _any_ kind, on condition that the results of such tests shall be published or communicated to the author for future publication. Address, W. T. Lewis, President Philadelphia Horological Society, Philadelphia, Pa. FOOTNOTES: [12] Thurston. Friction and Lost Work in Machinery. [13] As the fish from which these oils are obtained are of the mammalia order, their oils are classed among the animal oils. [14] The Horological Journal, Apr., 1881. Vol. xxiii. Page 98. [15] Pharmacopoea Germanica. 1882. [16] The National Dispensatory. 1884. [17] Saunier, Watchmaker's Hand-Book, p. 104, Eng. Edition; p. 129, Am. Edition. [18] Brannt. Animal and Vegetable Fats and Oils. [19] Paper read in the Chemical Section, British Association, Plymouth Meeting, 1879. [20] Swansea Meeting. British Association, 1880. [21] This work is compiled from a course of lectures delivered by the author before the Philadelphia Horological Society, 1896. [22] Thurston. Friction and Lost Work in Machinery. [23] Proceedings N. E. Cotton Manufacturers' Association, Nov. 28, 1880. [24] The average teaspoon holds 5 cubic centimeters. [25] 1 millimeter = .039 + inch. [26] Thurston. Friction and Lost Work in Machinery.