48 ANALYSIS AND ADULTERATIONS OF BUTTER. 



for saponification. As butter most readily dissolves in -warm 

 alcohol, the action of the potash is greatly facilitated, both 

 oil and aLkaU being in solution, and consequently moat inti- 

 mately mixed, whilst the butter-fat merely floated on the 

 aqueous lye, offering but a small surface for action. Saponi- 

 fication in alcoholic solution appears in fact to be nearly 

 instantaneous provided the liquid be warm, but even in cold 

 solutions it proceeds with great speed. 



Thus modified, the original, tedious, troublesome, and 

 inaccurate method was at once rendered quick, exact, and 

 even elegant ; one which takes neither more time, manipu- 

 lation, nor skUl than the average of analytical methods ; it 

 requires indeed scrupulous care, but this can hardly be 

 raised as an objection, seeing that the most exact of 

 methods is rendered valueless without it ; it requires, more- 

 over, rigid observation of the rules we will presently refer 

 to, and which are dictated by the practical experience 

 obtained from the analyses of some hundreds of samples 

 of butter we have ourselves made. 



/ Before detailing the method for the determination of the 

 insoluble fatty acids, we wUl shortly mention the most im- 

 portant results arrived at. The percentage of fatty acids 

 in butter fat, made from the milk of cows of the most 

 varied breed, of different countries, fed with green or with 

 dry food, and in different seasons, varies usually between 

 86'6 and 87'5, though it in some rare instances falls as 

 low as 86 '3, and rises as high as 88"5 per cent. A fair 

 average is represented by the figure 87 '3 per cent. 



It is thus established that the amount of insoluble fatty 

 acids is a tolerably constant figure, as constant in fact as 

 can reasonably be expected, considering that no animal 

 product can from the nature of animal life be ever in- 

 variably the same (excepting of course definite compounds, 

 such as urea, etc.). 



