128 



ANALYSIS OF MILK. 



iodide (13 '55 grammes mercuric chloride and 36 grammes potas- 

 sium iodide per litre) and 2 c.c. of acetic acid, the volume made 

 up to 200 c.c. and the liquid filtered. To 100 c.c. of the clear 

 filtrate are added 10 c.c. of a solution of potassium cyanide 

 equivalent to a decinormal solution of silver nitrate and 12 or 



. N 

 15 c.c. of ammonia. The liquid is then titrated with — silver 



nitrate solution until there is a permanent turbidity. The 

 number of c.c. used = q. 



A blank determination is made to determine the exact value 

 of the silver nitrate solution. 10 c.c. of the cyanide solution, 

 12 to 15 c.c. of ammonia, and 10 c.c. of the mercuric-potassium 

 iodide solution are mixed with 100 c.c. of water and titrated, 

 as before, with the silver nitrate. The number of c.c. used 



N" 

 (which with ^t; silver nitrate should be 4'8 c.c.) = c. The per- 

 centage of proteins is calculated from the value q — c by means 

 of Table XII. 



TABLE XII. — For Calculating Percentage of Proteins 

 IN Milk. 



Trillaut and Sautonbase a method on the fact that formalde- 

 hyde renders the proteins of milk insoluble. Five c.c. of milk 

 diluted with 25 c.c. of water are boiled for five minutes, then treated 

 with 5 c.c. of 40 per cent, formaldehyde solution, boiled for two or 

 three minutes longer, and allowed to stand for five minutes. 

 The solution is shaken with 5 c.c. of a 1 per cent, solution of 

 acetic acid, and the precipitate collected on a dried filter or 

 Gooch crucible, washed with water, and subsequently extracted 



