10 HANDBOOK FOR BIO CHEMICAL LABORATORY. 



trate from the magnesium sulphate with sodium sulphate 

 (or ammonium sulphate) at 20 C. The precipitate of ov- 

 albumin is filtered off and pressed between filter-paper, dis- 

 solved in water, again precipitated with sodium sulphate (or 

 ammonium sulphate), and after repeating this process several 

 times the salts are removed by dialysis, and the salt-free 

 solution evaporated to dryness at 40 C., or in a vacuum. 



Properties. The ov-albumin remains as a yellowish, trans- 

 parent mass soluble in water, precipitated from its solutions 

 by alcohol, and quickly converted into coagulable albumin. It 

 is not precipitated from its watery solution by MgS0 4 , but 

 completely precipitated by NH 4 S0 4 . Its 1-3$ solution con- 

 taining some salt coagulates at about 56 C. It is not pre- 

 cipitated by ether, and has a specific rotatory power of (a) 

 V = 35.5. 



Serum Globulin or Paraglobulin. 



1. Faintly acidify blood serum (prepared as directed on 

 page 8) with a few drops acetic acid, and dilute with 10-20 

 vols. of water. The serum globulin will separate as a fine 

 flocculent precipitate, which is filtered and further purified 

 by dissolving it in a dilute common-salt solution or in water 

 by the aid of the smallest possible amount of alkali, and then 

 reprecipitating by diluting with water or by the addition of a 

 little acetic acid. On repeating this twice the serum globulin 

 is carefully dried in the air. (Al. Schmidt.) 



2. Serum may also be precipitated from blood serum by 

 means of magnesium or ammonium sulphate added to satu- 

 ration. Filter and wash with one-half saturated solution of 

 the salt used, and purify the precipitate by means of dialysis. 

 As ammonium sulphate is removed by dialysis with difficulty, 

 it is best to use magnesium sulphate. When great purity is 

 required the precipitate may be redissolved by adding distilled 

 water, reprecipitating by saturating with the salt again, and 

 purifying this by thorough dialysis. (Hammarsten.) 



