ANALYSES OF CHEESE. 



381 



cheese taken, and dividing by one-tenth of the weight of the 

 cheese. 



The remainder of the filtered liquid (50 c.c.) is brought, by 

 the addition of water, to 150 c.c, and distiUed into standard acid, 

 to determine the free ammonia ; this determination is not very 

 exact as ammonia is gradually liberated as the distillation pro- 

 ceeds ; hence it is usual to stop the distillation when 75 c.c. 

 have distilled over. A little calcined magnesia suspended in 

 25 c.c. of water is next added, and about 50 c.c. are distilled into 

 standard acid for the estimation of combined ammonia. 



The residue in the distilling flask is rendered acid by the addi- 

 tion of a little sulphuric acid, and made up to 55 c.c. ; 40 c.c. 

 are distilled off, and the volatile acid received in standard alkali. 

 The acid is calculated as butyric by multiplying the number 



N 

 of c.c. of r-^ alkali used by the factor 0'00975 (this factor assumes 



that 90 "2 per cent, of the total acid will be obtained under these 

 conditions). 



He gives the following analyses : — 



TABLE (JI. 



Volatile Acids. — The following proportions of volatile acids 

 per 100 of fat are instructive : — 



TABLE CIL 



Frush cunl, ....•• 

 Curd tlNc ila3-s old, ... 



,, i-iL;hl ., 



Cliui'su frnm the same curd two months old, 

 Cantal clieeso, .... 



F.it from above rancid after one month, 

 .Salcis cheese (l)itter), .... 



(taste good), 

 Clieese five years old, .... 



0'04 per cent. 



-.-..I 



:2-33 

 3 

 3-2 

 0-2 



•2 

 71-2 



