26 



Mr. E. G. Young. On the Optical Rotatory 



in some attempts to purify serum albumin in like fashion, more difficulty 

 was experienced in arriving at a homogeneous product by reason of pigment 

 contamination. The last study of serum albumin was carried out by Hardy 

 and Gardiner, and only published in abstract form. By means of absolute 

 alcohol and anhydrous ether as extraction solvents and dehydrating agents at 

 — 4° C, a snow-white protein was obtained, which could be readily dissolved 

 and crystallised. This mode of preparation serves to remove all traces of 

 fatty material present in the original precipitate from serum, and has been 

 used in part of the experimental work. The claim is made by these authors, 

 unfortunately on very little published experimental evidence, that the 

 albumin in serum exists as a complex of albumin, cholesterol esters and two 

 pigments. This point is discussed later in the light of my experimental 

 findings. 



The various values recorded in the literature for the specific rotation of 

 serum albumin are given in Table IX. 



Table IX. 



Observer. 



Material. 



Specific rotation. 



Frederioq (1880) 



Amorphous 



-56-07 to -58-41 



Starke (1881) 





-60 -05 



Sebelien (1885) 



3' 



-60 -1 to -62 -6 



Michel (1898) 



Crystalline 



-61 -0 



MaximoTitsch (1901) 





-47-47 



Preparation of Material. 



Two methods of preparing albumin have been followed with a view to- 

 contrasting the products obtained, the alcohol-ether method of Hardy and; 

 Gardiner, and a procedure evolved from the general principles of the 

 Hopkins-Pinkus method. The blood was drawn from the right jugular 

 vein of a normal horse and collected in sterile Winchesters, where it was 

 allowed to clot spontaneously. The serum was siphoned off after 2 or 

 3 days. With one preparation the blood was first defibrinated, and then, 

 centrifuged free from corpuscles. 



Method 1. — -The serum obtained was transported to cold storage chambers,, 

 where it was poured into three times its volume of 95 per cent, alcohol at a 

 temperature of —4° C. The proteins thus precipitated were allowed to 

 stand for 24 hours, when filtration was commenced through folded filters.. 

 The bulky cream coloured precipitate was washed at —4° O. as follows : 

 (1) three times with 95 per cent, alcohol; (2) twice with absolute alcohol;. 



