ANALYTIC PROCESSES 29 



tion of casein are mixed, the albumin precipitated 

 by Alm6n's tannin reagent, filtered, and the 

 nitrogen in the precipitate determined as above. 

 The same factor is used. 



Almin's reagent is prepared by dissolving 4 

 grams of tannin in 190 c.c. of 50% alcohol and 

 adding 8 c.c. of acetic acid of 25%. 



In a mixture of milk and whey (prepared with 

 rennet) in about equal parts, Richmond and 

 Boseley found about 0.3 % of albumoses not pre- 

 cipitated by the copper sulfate nor by magnesium 

 sulfate, but precipitable, along with the albumin, 

 by a solution of tannin. The separation may be 

 effected by diluting the filtrate from the magne- 

 sium sulfate precipitation, acidifying slightly with 

 acetic acid, and boiling, when the albumin will be 

 coagulated and precipitated. The albumoses 

 may be separated by filtering the solution and 

 precipitating with tannin solution. The pre- 

 cipitated proteins are best estimated by de- 

 termitiing the nitrogen in the moist precipitate. 

 The separation of the proteins may be effected, 

 though less accurately, but the use of acetic acid, 

 as recommended by Hoppe-Seyler and Ritt- 

 hausen. 



Leffmann and Beam have modified the process 

 to avoid the delay and trouble of washing the 

 precipitate, as follows: 10 c.c. of the milk are 

 mixed with saturated magnesium sulfate solu- 



