1. Thompson, National Petroleum News,28, No. 6, 29 (1936).
2. Archbutt and Deeley, “Lubrication and Lubricants,” Fifth Edition, Charles Griffin and Company, Limited, 1927, p. 17.
3. Wells and Southcombe, British Patent, 130, 377 of February 5, 1918; U. S. Patent 1,319,129 of October 2, 1919; Mexican Patent 18,915 of February 5, 1918; Canadian Patent 196,215 of January 20, 1920.
4. Hersche, Bull. 112, Am. Instrument Co. (1929);
5. Chem. and Met. Eng., 28, 302 (1923).