ANALYSIS OF BUTTER-FAT. 75 



are in all probability present in a complex form, the radicals 

 of the volatile fatty acids being combined with glycerin and 

 the fixed fatty acids in the same molecule to form compound 

 ethereal salts." 



"We have repeated these experiments, and entirely concur 

 with the conclusions at which Mr. Bell arrived. Butter-fat 

 is therefore to be regarded as glycerine, in which one portion 

 of the hydrogen is substituted by the radicals of palmitic 

 and oleic acid, and the other by the radicals of the soluble 

 acids, amongst which, according to Dr. Dupre, butyric acid 

 by far predominates. In other words, butter-fat is a mixed 

 ether. 



Such a theory would also explain the great constancy of 

 the composition of butter. Of course, the pure mixed ether 

 is never produced, but is always associated, to a greater or 

 less extent, with other glycerides. 



Stearic acid appears to be absent from butter-fat, whilst 

 palmitic acid seems to be present in large quantities. Hence 

 we may assume, for a moment, that butter-fat consists of such 

 compound palmitic and oleic ethers. Both the di-palmitate, 

 mono-butyrate and the di-oleate mono-butyrate would yield 

 less insoluble acids than is found in practice, the former 80'2 

 and the latter 84'6 per cent. But a mixture of compound 

 ethers such as would be obtained by substituting in the tri- 

 palmitate or n'-oleate of glycerine one atom of hydrogen of 

 the acid radicle by the radicle of butyric acid would very 

 approximately yield proportions of insoluble and soluble 

 fatty acids as are actually found. "Whether butter-fat be or 

 be not such an ether cannot at present be decided. Yet the 

 question, from a scientific point of view, is highly interesting, 

 and seems near the point of its solution. 



