338 KiRKWOOD AND GiES : Chemical Studies 



The following facts regarding cocoa-oil have been compiled 

 from various sources. They may be compared with similar data 

 for other fats and oils given in the standard works of Konig, 

 Staedeler, Lewkowitsch and others : 



A. The heat of combustion of cocoa-oil is 9,066 small calories 

 per gram.* It is as low as that of any other fat ; slightly lower 

 than butter. This is due to the fact that it contains a large pro- 

 portion of fatty acids of low molecular weight. 



B. Melting point is at 24° C. Congealing temperature is 22- 

 23° C. Fatty acids from it melt at 24.6° C. They congeal at 



19° c.t 



C. Saponification value = 257. 3-268. 4! 



D. Iodine number = 9.O-9.5 ; same for its fatty acids = 8.5- 



9-0.§ 



E. Specific gravity = 0.9 11 5 at 40° C.|| 



F. Acid value = 9.95-35.21. 



G. Reichert-Meissl figure = 7.4 ; Hehner = 88.6-90.5. 

 H. Barium figure (Konig-Hart) = 117-120. 



I. Molecular weight of the mixed fatty acids = 196-21 1. 



The use of cocoa-fat and other cheap vegetable oils as a 

 substitute for butter among the poorer classes has been in- 

 creasing. Cocoa-fat is better adapted for cooking than for table 

 use. It is frequently employed as an adulterant of ordinary 

 butter. Prepared cocoa-fat makes a fairly good substitute for com- 

 mon butter. The fresh material becomes rancid after a time, 

 because of its accumulating content of free fatty acid resulting from 

 bacterial agency. Volatile acids are formed. Its tendency to 

 rancidity is not as great, however, as that of animal fats. The 

 fatty acid present in the fat to begin with can easily be removed 

 with insoluble basic compounds, such as magnesia. By this means 



* Merrill. Quoted by Sherman and Snell : Journal of the American Chemical 

 Society, 23 : 166. 1901. 



\ Konig : Menschlichen Nahrungs- and Genussmittel, etc., 2 : 322. 1893. 

 J Konig : /die/. 



I Benedikt. Quoted by Vaubel : Physikalischen und chemischen Methoden 

 quantitativen Bestimmung organischer Verbindungen, 2 : 235. 1902. 



II Values given after E-I inclusive are quoted by Hopkins : Oil-Chemists' Hand- 

 book, 38, table iv. 1900. See also Lane : Journal of the Society of Chemical 

 Industry, 20 : 1083. 1901. 



