CH. II.] ALBUMINS AND GLOBULINS. 45 



NOTE. The results in this exercise are similar to those obtained in Ex. 27, 

 except that the increased alkalinity prevents the formation of the opalescence 

 obtained in the absence of added alkali. 



31. To 5 cc. add a drop of 2 per cent, calcium chloride and boil. 

 A considerable coagulum is obtained. 



NOTE. Though the solution is alkaline to the iso-electric point, the di- 

 valent positive calcium ion precipitates a certain proportion of the negative 

 colloidal protein. 



F. The properties of albumins and globulins. 



Globulins are generally insoluble in distilled water, but 

 soluble in dilute acids and alkalies, and in weak solutions 

 of neutral salts. 



A neutral solution in a dilute salt is coagulated on 

 boiling. 



A solution in dilute acid or alkali is converted into a 

 solution of metaprotein on boiling. 



If the globulin be dissolved in a minimum amount of 

 a neutral salt solution and the solution be diluted with 

 several volumes of distilled water, the globulin is partially 

 precipitated, for a certain concentration of salt is necessary 

 to keep the globulin in solution. If the globulin be dis- 

 solved in dilute acid or alkali, there is no precipitation on 

 dilution. 



The globulins are completely precipitated by full 

 saturation with magnesium sulphate or by half-satura- 

 tion with ammonium sulphate, i.e. by treatment of the 

 solution with an equal volume of a saturated solution of 

 ammonium sulphate. 



Albumins are soluble in distilled water, dilute salt 

 solutions, dilute acids and alkalies. 



A neutral solution in water or salt is coagulated on boil- 

 ing. 



A solution in dilute acid or alkali is converted to a 

 solution of metaprotein on boiling. 



Solutions of albumins are not precipitated by saturation 

 with magnesium sulphate nor by half-saturation with 



