Lubricating Oils, Fats and Greases; Their Origin, Preparation, Properties, Uses and Analysis (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 edition. Excerpt: ... X = percentage of oil A in sample. A = mean rise for pure sample of oil A., ," it-D. C = observed rise in the mixed sample. Thus, supposing in a mixture of olive oil and cotton seed oil the observed rise was 56 C., then according to the above formula we have (56-44) x 100_ 12 x 100 65-44 21 = 57-1 per cent, of oil A. Then there are 571 per cent. cotton seed oil and 429 per cent. olive oil in the mixed sample. 4. Free acid test. It is important that lubricating oils should be free from acid whether this be of fatty or mineral origin, as such free acid has a destructive effect on the metal of machinery, and it is astonishing what a corroding effect a small quantity of free acid in oil has on metals, especially on brass or copper when the two bodies have been in contact for some time. If an oil containing 3 per cent. of free acid be left in contact with brass for 12 hours it will have acquired a green tint, showing that it has dissolved some of the metal. Fat oils such as olive, rape, castor, cotton, generally contain small quantities of free acid, rarely less than 1 per cent., and the writer has found as much as 22 per cent. of free fatty acid present in oils. This free acid may have been present originally in the oil owing to defective methods of extraction, or if the sample be an old one may have developed by keeping. All fatty oils on keeping for sometime slowly become rancid, some oils more rapidly than others. This rancidity is brought about by the combined action of the oxygen and moisture present in the air with which they are in contact, and results in the decomposition and splitting up of the ojl into its two constituent parts--glycerine and fatty acid. Fatty acids have a strong corroding action on metal. Mineral oils are usually...