ANALYSIS OF BUTTER-FAT. 59 



extent by the decomposition of the butter. Mr. Bell made 

 analogous experiments, and came to precisely similar results. 

 To ascertaia the influence of the food of the cow upon 

 the amount of fat acids in butter, Dr. Turner caused a cow to 

 be fed for a considerable length of time, as far as practicable, 

 with oil cake, with the view, if possible, to raise the per- 

 centage. The butter was analysed by Dr. Turner, Dr. 

 Muter, and by each of the authors. The following are the 

 results : — 



86-22 per cent. fT») 86-41 per cent. (H^) 



86-23 „ „ (H'') 87-1 „ „ (A') 



87-2 per cent. (M") 



After a week the butter was again analysed, and furnished 

 the following results : — 



86-6 per cent. (H") 86-8 per cent. (H°) 



87-0 per cent. (T*) 



Thus the determiaations conclusively prove that the 

 percentage of the insoluble fatty acids does not rise even 

 under that kind of food, which might be supposed to exert a 

 deep influence upon the composition of the butter. We 

 shaU again have occasion to refer to the above figures. (See 

 page 61.) 



As among the figures contained in the table given above 

 there are represented winter and summer butters, and 

 specimens of the best quality of fresh and the worst of salt 

 butter ; of the finest Aylesbury and the most inferior Dutch 

 or Brittany; English, Irish, French, and German, it may 

 safely be asserted that genuine butter, of whatever descrip- 

 tion or name, always yields approximately the same per- 

 centage of fatty acids. Exceptions may perhaps now and 

 then be found, but if they do occur they are very rare, and 

 may doubtless, as in the case of milk, be explained by illness 



