Dec.,
,1920
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
For some three years the writer has been using a modification of the second test, as follows: Five cc. of chloroform are added t o 5 cc. of t h e
oil, mixed in a small test tube with a few drops of gum arabic solution and 5 cc. of a two per cent solution of ursnium nitrate or uranium acetate, and shaken t o form a thorough emulsion. All samples of crude and refined soy-bean oil so far examined give a characteristic lemon-yellow emulsion, whereas no other oil so far tested gives this color. The most valuable use for the test has been in detecting admixtures of the cheap bean oil with highpriced wood oil or with linseed oil. With the former t h e test is sharp, i t being possible t o detect as low as 5 per cent of bean oil. The test is conducted by comparison with blends made u p with pure wood oil and pure bean oil. With linseed oil the test is not so sharp, as linseed oil mixtures always give a slightly brownish color. It has never been absolutely certain t h a t the linseed oil samples used for comparison were pure, and further work is in progress. With such oils as peanut, cottonseed, sesame, rape, and coconut, the test is very sharp, as these oils give white or slightly colored emulsions with the uranium salt. The yellow emulsion is not formed with bleached and deodorized bean oil, hydrogenated oil, or bean oil fatty acid. This Settini test for bean oil is not as sharp as some of the direct color tests characteristic of sesame or cottonseed oils, but nevertheless i t has been of great value in the eommercial testing of oils arriving from the Orient. This is no indication t h a t i t will work equally well with domestic soy-bean oil. Since the yellow emulsion seems t o be due to the presence of coloring matter in the crude oil rather t h a n t o some substance inherent t o t h e oil, this coloring matter may be characteristic of only certain varieties of soy bean. Until the exact nature of the yellow emulsion is cleared up, the Settini test should be used with caution, and its limitations taken into account.
THE OIL OF THE PRICKLY PEAR SEED1 By S. Lomanitz COLI,EG~ STATION, TEXAS
The prickly pear is offered for sale as a refreshing fruit a t street corners in Mexican towns. I n some places the pulp is made into a delicious hardened jelly and put up in form of bricks. These jelly bricks, panes or quesos (literally cheeses), as they are called, possess very,good keeping qualities and can be found €or sale in candy and confectionery stores all through Mexico, a goodly number of them finding their way even into this country. I n making these quesos the seeds are dfsposed of as waste. Analysis of the seeds of a more or less cultivated variety of white prickly pear, known as t u n a blaca d e huerta, gave the following result: 1 Read before the Central Texas Section of the American Chemical Society, May 7, 1920
Moisture.
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Per cent 7.68 2.96 10.89
The oil, which was obtained by extracting the seed with petroleum ether, was greenish yellow in color, odorless, and somewhat viscous at ordinary temperatures. The following constants of the oil were determined according t o the methods recommended by Lewkowitsch. Specific gravity, 15.5/15.5. . . . . . . . . . . . . . . . . . . . 0.9294 Acid number. Free fatty acids, as oleic acid.. Saponification value.. 189.5 Iodine number. 116.30 186.47 Ester number. 2.8 Reichert-Meissl number.. 93.81 Hahner number. 1.46764 Index of refraction, w v .
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From the data on hand, the oil apparently falls into the group of semi-drying oils, and produced in sufficient quantities might be used in some of the oil-products industries. THE DETERMINATION O F CRUDE FIBER IN PREPARED MUSTARD By M. C. Albrech THER. T. FRENCH Co.,ROCHESTER, N. Y. Received May 27, 1920
The method for the determination of crude fiber in prepared mustard given in the Jowrnal of the Association of O s c i a l Agricultural Chemists1 differs from the general method for crude fiber in t h a t the fat is not extracted before treating with 1 . 2 5 per cent sulfuric acid, i t evidently being considered impracticable t o do so. Upon investigation of the present method by the author i t was discovered t h a t while certain samples gave results which might be somewhere near the true figure for crude fiber, other samples gave results clearly impossible. Samples of prepared mustard which contained little oil gave better results than samples which contained a larger amount, showing clearly t h a t the oil interferes with the method, and gives results much too high. Washing with alcohol and ether t o remove residual oil after treatment with acid and alkali, would, of course, not prevent the interfering action of the oil during the operation. The method devised t o correct this defect consists in a preliminary treatment of the prepared mustard, as follows: 8 g . of the material are weighed into a 500-cc. Erlenmeyer flask, I O O cc. of boiling water are added, and the flask stoppered and shaken vigorously, t o disintegrate the prepared mustard. The solt tion is then immediately filtered on a filter paper on a Buchner funnel, and the residue is immediately washed with alcohol, then with ether repeatedly, until the fat is removed and the ether washings are colorless. The material remaining on the paper is immediately washed, or carefully scraped and washed off the filter with zoo cc. of boiling, 1.2 j per cent, sulfuric acid, and the determination completed according t o the regular 12, No. 3, Part 2
