106 THE BLOOD. 



234. Separate the serum from blood by collecting the 

 freshly-drawn blood in a shallow vessel and letting it stand 

 covered until it has coagulated and the serum is pressed 

 out by the contraction of the coagulated mass. 



235. Show that the serum contains albumins by test- 

 ing a diluted solution by 



1. Heat. 



2. Biuret test. 



3. Xanthoproteic test. 



236. Separate the proteins of the serum by adding 

 to a portion an equal volume of a saturated solution of 

 ammonium sulphate. This precipitates the serum glob- 

 ulin. Filter it out, dissolve it in water, and try the glob- 

 ulin reactions. Into the nitrate stir enough powdered am- 

 monium sulphate to completely saturate it. Serum albu- 

 min falls and can be filtered out, dissolved in water, and 

 tested. Test the filtrate for proteoses with acetic acid and 

 potassium ferrocyanid. They are not present. Peptones 

 are also absent. 



237. Slightly acidify a fresh portion of the serum 

 and boil to coagulate the proteins. Filter and apply Trom- 

 mer's test to the filtrate. Does the serum contain glucose ? 



238. Prepare fibrin by beating freshly-drawn blood 

 with a fork or a bundle of switches. When it has coagu- 

 lated, pour off the liquid and preserve it for further tests. 

 Wash the fibrin, at first in water to which a little salt has 

 been added, then in clear water. Break up the large clots 

 and continue the washing until the coloring matter is re- 

 moved. If it is desired to keep it, it can be preserved in 

 a 1-per-cent. solution of corrosive sublimate. 



239. After noticing the structure and elasticity of 

 fibrin apply the following tests: 



