SERUM PROTEINS. 263 



The crystalline and amorphous seralbumin in aqueous solution give 

 the ordinary albumin reactions. The coagulation* temperature of a 

 1-per cent solution, poor in salts is about 50 C., but rises with the quan- 

 tity of salt. The coagulation of the mixture of albumins from serum 

 generally takes place at 70-85 C., but is essentially dependent upon 

 the reaction and the amount of salt present. Up to the present time no 

 seralbumin solution has been prepared free from mineral bodies. A 

 solution as free from salts as possible does not coagulate either on boil- 

 ing or on the addition of alcohol. On the addition of a little common 

 salt it coagulates in both cases. 1 



Seralbumin differs from the albumin of the white of the hen's egg in 

 the following particulars: It is more levogyrate; the precipitate formed 

 by hydrochloric acid easily dissolves in an excess of the acid; it is rendered 

 less insoluble by alcohol. 



In preparing the seralbumin mixture, first remove the globulins, 

 according to JOHANSSON, by saturating with magnesium sulphate at 

 about 30 C. and filtering at the same temperature. The cooled filtrate 

 is separated from the crystallized salt and is treated with acetic acid so 

 that it containes about 1 per cent. The precipitate formed is filtered 

 off, pressed, dissolved in water with the addition of alkali to neutral 

 reaction, and the solution freed from salt by dialysis. The mixture of 

 albumins may be obtained in a solid form from the dialyzed solution, 

 either by evaporating the solution at a gentle temperature or by pre- 

 cipitating with alcohol, which must be quickly removed. STARKE 2 

 has suggested another method, which is also to be recommended. The 

 crystalline seralbumin may be prepared from serum freed from globulin 

 by half saturating with ammonium sulphate, by the addition of more 

 salt until a cloudiness appears, and then proceeding according to the 

 suggestion of GURBER and MICHEL. On acidifying with acetic acid 

 or sulphuric acid the crystallization may be considerably accelerated. 3 

 The quantity of seralbumin is best calculated as the difference between 

 the total proteins and the globulins. A method for the quantitative 

 estimation of globulins and albumins in blood serum by refractometric 

 means has been suggested by ROBERTSON/* 



Summary of the elementary composition of the above-mentioned and described 

 proteins (from horse-blood) : 



1 In regard to the relationship of neutral salts to heat coagulation,, see J. Starke, 

 Sitzungsber. d Gesellsch. f. Morph. u. Physiol. in Miinchen, 1897. 



2 Johansson, Zeitschr. f. physiol. Chem., 9; K. Starke, Maly's Jahresber., 11. 



3 See Hopkins and Pinkus, Journ. of Physiol., 23; Krieger, Ueber die Darstellung 

 krystallinscher tierischer Eiweissstoffe, Inaug.-Dissert. Strassburg, 1899. 



4 Journ. of biol. Chem., 11. 



