76 FOODS AND FOOD ADULTERANTS. 



(7) Crook 1 warms half a grain of the filtered fat in a test tube to 66 

 C., and adds 1.5cc. phenol, shakes and warms in water bath until the 

 liquid is clear. On standing pure butter gives a homogeneous solution- 

 Tallow and lard appear, however, in distinct layers. 



A method somewhat similar to this was proposed in 1877 by Bach. 2 

 The apparatus required consists of a test tube and a thermometer. 

 The reagent is a mixture of 3 volumes ether and 1 volume alcohol of 

 95 per cent, and 1 gram of the butter or tallow and put in the test tube 

 with 20cc. of the above mixture, and this is placed in water at 20 C. At 

 this temperature pure butter is completely dissolved. Butter, however, 

 containing lard, beef, or mutton tallow remains undissolved. 



(8) Horsely 3 calls attention to the perfect solubility of pure butter in 

 ether, and that it is not precipitated from this solution by methyl- 

 alcohol, while other common fats are thus separated at 20 C. 



Leuz 4 confirms the general results of the foregoing process. 



(9) Belfield 5 allows the fats dissolved in ether to crystallize, and 

 distinguishes between them by their crystalline form. 



(10) Paillat 6 has found that pure butter when mixed with copper oxide 

 in ammonia gives a turquois blue color, while a butter adulterated with 

 margarine (?) gives a greenish tint. 



(11) Dubois and Fade 7 point out that the addition of any considerable 

 quantity of foreign fats to butter not only changes the melting point of 

 the fatty acids obtained, but also diminishes their solubility in alcohol. 



(12) Wolkenhaar 8 distinguishes between the different fats by means of 

 nitric acid, which gives to cotton seed oil, palm oil, lard, sesame oil, and 

 several others a red brown color. 



For a fuller discussion of most of these qualitative tests, consult 

 either the original articles or Sell. 9 



(13) Method of Mayer. 10 This test is made as follows : 



About 0.6 gram of butter fat is placed in a test tube with 12cc. water 

 made slightly alkaline by a few drops of a solution of 2 per cent, soda, 

 or two drops of C per cent, ammonia- water. The tube closed by the 

 thumb is then well shaken, afterwards carried to a temperature of 37 C. 

 to 40 C., with frequent shaking. The emulsion thus formed is poured 

 into a separatory funnel. The fat is now washed several times with 

 water at 37 0. to 40 C., the wash- water being drawn off by the stop-cock 

 so as to maintain a constant level in the funnel. The fatty matter having 

 thus been placed in contact with about 400cc. water, the stop-cock is so 



1 Analyst, 1879, p. 111. 



2 Pharm. Centralh., 1877, p. 166. 



3 Chein. News, vol. 30, p. 135 and 154. 



4 Zeit. Anal. Chem., 1880, p. 370. 



5 Rep. d. Ver. Anal. Chem., vol. 3, p. 383. 



6 L'Aunde Scientifique par Louis Figuier, 29th year, 1885, 



7 Bui. Soc. Chiin., vol. 44, p. 602. 



8 Rep. d. Ver. Anal. Chem., vol. 3, p. 103. 



9 Op. cit., pp. 505-509. 



10 Jour, de Pharm. et de CMm., vol. 15, p. 97, 



