PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 933 



docs not produce any clnuige in the beginning, l>nt after 24 hours 

 it thickens and changes to. a dark olive green. By adding lime 

 ■svatcr, the oil solidifies at once and takes a dirty, brownish yellow 

 color. Sulphurous acid gas, when passed through it does not 

 decolorize it, nor do the chlorides of zinc and tin, nor the acetate 

 of lead, produce any remarkable change. In its oxydized state, 

 and probabl}^ also under the influence of the vegetable matter con- 

 tained in the oil, the coloring pigment seems to be very much 

 inclined to cake together to a fatty mass. As concerns the crude 

 oil, it solidifies between 28° and 26.5° F.; it is very well adapted 

 for preparing hard and soft soaps and is a good substitute for lin- 

 seed oil in dark paints, varnishes, and, perhaps, also in printing ink. 

 The so-called refined oil, of which the best quality, as regards 

 odor and taste, is very similar to olive oil, solidifies between 28 

 and 32° F Its specific gravity is 0.92647, at 60.5° F. it is 1.7 

 times less limpid than water. Properly speaking, it is more or 

 less pure olein. In Italy, where the cotton culture has recently 

 been introduced, it is used as a burning fluid, and not seldom as 

 an admixture to clearer oils. One hundred pounds of crude oil 

 yields 290 pounds soft soap, containing 52.65 per cent of water,, 

 and 170 pounds of hard sojip, of a water amount of 38 per 

 cent. Lead plaster was obtained hy direct saponification of the 

 oil with oxide of lead, as well as by double decomposition of both,, 

 by precipitating a solution of soap with acetate of lead ; 100 potash, 

 soap yielded 57 dry lead soap. The dark color of the oil is visi- 

 ble in all these soaps, but least in the soda soap. The refining of 

 the oil, i. e., the separation of the coloring matter and the obtain- 

 ing of a better article, can simply be done by washing it with 

 potash or soda lye, but it is good to separate first the slimy and 

 albuminous matter by the introduction of steam, and washing withi 

 boiling water. By the action of the alkali, not only the dark pig- 

 ment is solved, but also a part of the oil is saponified. In leaving 

 it at repose, the mixture of the oil and alkaline settles into three 

 diflerent layers, of which the top one forms the colorless refined 

 oil, while the dark colored middle one forms the saponified fat, 

 and the dark at the bottom, the black alkaline lye. Steamed oil 

 treated with oil yields, under favorable conditions, 85-88 per cent., 

 of refined oil. It is said that very great quantities of it are 

 . employed for adulterating the olive oil. Pols has patented the 

 following method for refining cotton seed oil : One hundred parts- 

 of the crude oil are mixed with 12 parts of a solution of 42° 



