28 



B. BUTTER, FATS, AND OILS (FRESH). 



Coal-tar colors will be present with few exceptions in the form of 

 nonsulfonated bases and will be indicated by the following tests: 



a. BUJARD AND BAIER TEST." 



Two to 3 grams of fat are dissolved in 5 cc of ether and shaken with 5 cc of concen- 

 trated hydrochloric acid (1.125). If coal-tar colors are present the solution will be 

 colored decidedly red. Precaution: "Butter yellow" does not color hydrochloric 

 acid (1.19), or does so only slightly. The acid solution may then be used for double 

 dyeing a piece of wool, as described under " Wines," and the wool or the extracted 

 dye further examined. 



b. VANDRIKEN TEST. 6 



J. Vandriken states that pure butter is completely decolorized by 

 amyl nitrite. Proceed as follows: 



1. Amyl nitrite (acid). To 2 cc of filtered butter add an equal volume of ether in 

 a test tube. To this add 6 to 10 drops of amyl nitrite, and shake. Pure butter is 

 decolorized at once. If unfiltered butter is used, more reagent must be added, and 

 usually slightly warmed. 



2. Nitrous ether. To 2 cc of filtered butter add 2 cc of ether and 25 to 30 drops of 

 nitrous ether and shake vigorously. The decolorization takes place more slowly 

 than with amyl nitrite. Carotin is not decolorized; saffron, only slighly altered; 

 curcuma, not decolorized ; orlean, decolorized; annotto, not decolorized. 



c. LEEDS METHOD. 



One hundred grams of butter should be dissolved in a tapped separator in 300 cc of 

 petroleum ether of about 0.638 sp. gr. The water, etc. , is tapped off, and the ethereal 

 solution of the fat and coloring matters washed several times by agitation with water. 

 The ethereal solution, poured off from the stearin which may have separated on 

 "standing, is then shaken with 50 cc of N/ 10 caustic potash solution, which is sufficient 

 to effect the solution of all coloring matter capable of being dissolved by dilute 

 alkali/' The alkaline solution is separated from the ethereal layer and very cau- 

 tiously treated with dilute hydrochloric acid until faintly acid to litmus. The precipi- 

 tate, consisting of coloring matter mixed with a little fatty acid, is filtered off and 

 washed with cold water. If desired it may be weighed. The following table shows the 

 reactions of the coloring matters, isolated in the above manner, when two or three 

 drops of their alcoholic solutions are treated with an equal measure of the reagents 

 (acids) mentioned. 



a Hilfsbuch fur Nahrungsmittelchemiker, 1900, 144. 

 &Ann. Pharm., 1901 (7), 110; Chem. Ztg. Rep., 1901, 106. 

 c Analyst, 12, 150; Allen, 3 (1), 355. 



d A pale yellow color remaining in the petroleum ether is due only to the natural 

 coloring matter of the butter. 



