72 ANALYSIS AND ADULTERATIONS OF BUTTER. 



Thus we conclude that the determination of soluble acids 

 is no sufficient corroboration to that of the insoluble acids, 

 and that the amount of the latter alone need be known, 

 in order to enable the analyst to form an opinion about any 

 given sample of butter. 



The following table shows the quantities of soluble acids 

 corresponding to different percentages of insoluble acids, 

 assuming that butter-fat consists merely of tri-butyrin and 

 tri-stearin or olein. Of course the figures are only approxi- 

 mate, as so large a proportion of the insoluble acids consists 

 apparently of palmitic acid. 



Insoluble Acids. Soluble Acids corresponding. 



86 per cent. 8 -88 per cent. 



87 7-97 



88 7-06 



89 6-15 

 89-5 5-69 



After the presence in butter-fat of considerable quantities 

 of soluble acids had been fully proved, and no doubt could 

 be entertained that our original conclusions were essentially 

 correct, based though they were upon imperfect methods of 

 investigation, Mr. Wanklyn ingeniously suggested, though it 

 is difficult to see for what reason, that these soluble acids 

 were not really present as such (of course combined with 

 glycerine) in butter, but were only the product of the action 

 of the alkali employed for saponification, upon the higher 

 fatty acids. It is well known that the acids of the Acrylic 

 series, C n H 2n - 2 02, easily split up when acted upon by 

 caustic alkalies, forming acetic acid and an acid containing 

 two atoms of carbon less than the original acid; thus 

 C 18 H 34 2 oleic acid + 2 KOH = C 2 H 3 K0 2 (acetate) 

 + C 16 H 31 K0 2 (palmitate) + H 2 ; and there is good reason 



