GLOBULINS. 103 



precipitated by the addition of large quantities of mineral acids or metallic 

 salts. Their solution in water coagulates on boiling in the presence of 

 neutral salts, but a weak saline solution does not. If NaCl or MgS04 

 is added to saturation to a neutral solution in water at the normal tem- 

 perature or at 30 C. no precipitate is formed; but if acetic acid is added 

 to this saturated solution the albumins readily separate. When ammonium 

 sulphate is added to one-half saturation the albumin solutions are not 

 precipitated at ordinary temperatures. Of all the native proteids the 

 albumins are the richest in sulphur, containing from 1.6 per cent to 2.2 

 per cent. So far as they have been investigated they do not yield any 

 glycocoll on acid hydrolysis. 



Globulins. These substances are, as a rule, insoluble in water, but 

 dissolve in dilute neutral salt solutions. The globulins are precipitated 

 unchanged from these solutions by sufficient dilution with water, and 

 on heating they coagulate. The globulins dissolve in water on the addi- 

 tion of very little acid or alkali, and on neutralizing the solvent they 

 precipitate again. The solution in a minimum amount of alkali is pre- 

 oipitated by carbon dioxide, but the precipitate may in certain cases be 

 redissolved by an excess of the precipitant. The neutral solutions of the 

 globulins containing salts are partly or completely precipitated on satura- 

 tion with NaCl or MgSO4 in substance at normal temperatures, depending 

 upon the kind of globulin. The globulins are completely precipitated 

 by half-saturating with ammonium sulphate. The globulins contain an 

 average amount of sulphur generally not below 1 per cent. As a differ- 

 ence between the albumins and globulins the latter yield glycocoll among 

 the hydrolytic cleavage products, and according to OBERMAYER and 

 WILLHEIM x they contain fewer NH2 groups at the end of the chain, as 

 determined by formol titration, as compared to the total number of N- 

 atoms. 



A sharp line cannot be drawn between the albumins and globulins 

 from their properties and this is shown from the researches of MoLL, 2 

 which show that by the action of dilute alkalies and warmth upon 

 seralbumin it attains the properties of serglobulin. It is evident that 

 we are here dealing with a change of the external properties of the 

 albumins to a greater similarity to those of the globulins, and not with 

 a true transformation of the albumin, which is free from glycocoll, into 

 globulin which contains glycocoll. The same follows from the observa- 

 tions of others. 3 This is an instructive example of the subordinate impor- 

 tance the solubility and precipitation properties have in the differentia- 

 tion of various groups of proteids. 



1 Bioch. Zeitschr., 38. 



2 Moll, Hofmeister's Beitrage, 4 and 7; also Breinl, Arch. f. exp. Path. u. Pharm., 65. 

 Obermayer and Willheim, 1. c.; R. Gibson, Journ. of biol. Chem., 12. 



