284 The Fermentation of Cacao 



alcohol ; (b) the saponification number ; (c) 

 the iodine value ; (cf) the volatile insoluble 

 acids. The author also determines the acidity 

 of the sample. In German tests the refracto- 

 meter index, the melting point, and Bjork- 

 lund's test are also required. Robin detects 

 coco-nut oil (5 per cent.) by finding the solu- 

 bility in alcohol (55*5) and comparing the 

 co-efficient obtained with the saponification 

 number. For pure cacao butter the constant 

 lies between 7 and 8, but is considerably de- 

 creased in presence of very small amounts of 

 coco-nut oil (Ann. de Chim. Anal., 1906, p. 454, 

 1907, pp. 14, 40, 87, 181). Coco-nut fat gives 

 a figure of 15 to 18 (cc. N/io NaOH for 

 5 grm.) for volatile soluble acids, considerably 

 higher than that for cacao butter, and at the 

 same time raises the saponification number 

 and lowers the refractive index and the iodine 

 figure. Bjorklund's ether solubility test is 

 valuable for the detection of wax, margarine, 

 and paraffin, especially when the melting-point 

 also is taken of the fat which is deposited on 

 cooling the solution to o. This melting-point 

 should not exceed 30. The acidity of com- 

 mercial cacao butter, when not rancid, is not 

 greater than 0*5 per cent., expressed as oleic 

 acid. Cacao butter is also adulterated by the 

 addition of fat from the pellicle and other 

 waste parts of the plant. This fat is less 

 aromatic than the true ' butter ' and rapidly 

 becomes rancid. It is hardly possible to detect 

 this adulterant with certainty." 



