576 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



Caseinogen. 



(1) 40 c.c. of saturated magnesium sulphate solution are added to 20 c.c. 

 of milk ; the powdered salt is then added until the solution is saturated. The 

 precipitate is allowed to settle, filtered and washed several times with saturated 

 magnesium sulphate solution. The filter paper and precipitate are put into a 

 Kjeldahl flask and the nitrogen estimated. The figure multiplied by 6*38 

 gives the amount of caseinogen. 



The amount of globulin is so small that it is neglected. 



The nitrate is used for the estimation of the albumin (below). 



(2) 10 gm. of milk are diluted with 90 c.c. of water at 40-42, 1-5 c.c. 

 of 10 per cent, acetic acid are added slowly, a few drops at a time, with 

 stirring until the liquid above the precipitate is clear or nearly clear. After 

 standing for 5 minutes the precipitate is washed 3 times by decantation, the 

 washings being poured through a filter ; the precipitate is transferred completely 

 to the paper. The nitrogen in the washed precipitate is estimated by 

 Kjeldahl's method. The figure multiplied by 6-38 gives the amount of casein- 

 ogen. The filtrate is used for the estimation of albumin. 



Albumin. 



(1) The filtrate and washings from caseinogen above (i) are treated with 

 Almen's reagent. 1 The precipitate is filtered off and washed. The amount of 

 nitrogen in this precipitate determined by Kjeldahl's method and multiplied 

 by 6-38 gives the amount of albumin. 



(2) The filtrate and washings from the caseinogen above (2) are neutra- 

 lised with sodium' hydroxide : 0*3 c.c. of 10 percent, acetic acid is added and 

 the solution boiled for 15 minutes. The coagulated albumin is collected on 

 a filter and washed ; the nitrogen in it is determined by Kjeldahl's method. 



1 4 gm. tannin in 190 c.c. of 50 per cent, alcohol and 8 c.c. of 25 per cent, acetic acid. 



