ii BUTTER 173 



the presence of cocoa-nut fat in butter, but as it does not differ 

 in principle from Polenske's, it will not be described in detail 

 here. It will suffice to mention that the details in apparatus 

 and procedure must always have the closest attention, for the 

 constants with which the results of the analysis are to be 

 compared differ according to the method of performing the 

 experiment. Naturally a great number of such methods can 

 be worked out, but if the time of distillation of the volatile acids 

 or of the whole analysis is varied, then a long series of tests with 

 pure butter and with cocoa-nut fat have to be made, in order to 

 determine the normal fluctuations in the amount of soluble and 

 insoluble fatty acids. Further, the figures which are obtained 

 from known mixtures of both fats must also be ascertained. 

 Miintz and Coudon express the relation between the insoluble 

 and the soluble fatty acids in the following way : 



Insoluble acids 



Soluble acids 



X 100. 



In the case of pure butter the ratio is from 10-15, whilst 

 with cocoa-nut fat it lies between 250 and 280, a very consider- 

 able difference. 



Latterly a number of other methods for the detection of 

 cocoa-nut fat in butter have been proposed. None of them, 

 however, have withstood the rigorous tests to which they have 

 been subjected. Perhaps the cadmium method recommended 

 by Paal and Amberger l will prove to give reliable results, but 

 it has not yet been sufficiently tested to allow of a definite 

 verdict being pronounced. 



Qualitative Tests for Cocoa-nut fat in Butter. 



The phytosterine test (p. 162) gives absolutely reliable results 

 in so far as it shows the addition of some vegetable fat, but it does 

 not prove what particular fat has been added. The two follow- 

 ing methods can be used to identify cocoa-nut fat, and where the 

 adulteration has been considerable the results are very reliable. 

 Both methods are based upon the characteristic shape which 

 the cocoa-nut fat assumes when it crystallises out. Soltsien's 2 



1 Zeitschr. fur Untersuch. d. Nahr.- und Geuussmittd, 1909, Vol. XVII, 

 pp. 1 and 23. 



2 Augsburyer Seifen-Zeitschrift, 1904, p. 898. 



