ON THE CRYSTALLOGRAPHY OF HEMOGLOBIN. 99 



the corpuscles are decolorized and the hemoglobin (of human, cat, dog, 

 and guinea-pig blood) crystallized in the lake-colored solution, it being 

 immaterial whether the oxygen from the air has been admitted or not. 

 Yet this method is not well adapted for the production of crystals on a 

 large scale. 



An observation made by Pasteur (Compt. rend. soc. biolog., 1863, 

 LVI, 739) is very noteworthy. He allowed dog's blood to stand in a balloon 

 of heated air at a constant temperature of 30 C. After 4 to 6 weeks the 

 air contained 2 to 3 per cent less of oxygen and just as much more of car- 

 bonic acid. A large mass of hemoglobin crystals was formed. After several 

 weeks not a single corpuscle was present. The clot was colorless and very 

 elastic, and associated with an incalculable number of crystals. 



Julius Bernstein (1866) conducted atmospheric air through a small 

 amount of chloroform into defibrinated blood. He noticed that the blood 

 soon became lake-colored, and that he could no longer find any corpuscles 

 in it. Every drop produced crystals when evaporated. Preyer supple- 

 mented this procedure by treating the diluted extract of the coagulum in 

 the same way. This yielded crystals, but not in great masses. Kunde had 

 already observed (1852) the favoring influences of chloroform, ether, and 

 alcohol on crystallization. 



Alexander Schmidt found that crystallization followed upon the addi- 

 tion of pure alcohol to dog's blood. He mixed fresh blood with one-half 

 to two-thirds its volume of alcohol until albumin began to separate and 

 then left the mixture undisturbed. After a time it became laked and 

 crystalline. 



Ether causes the very same thing. Defibrinated dog's blood is shaken 

 with ether until the blood is laked and smells of ether. If it is allowed to 

 stand for 24 hours in the cold crystals can be seen microscopically in every 

 drop. 



Later A. Schmidt saw that dog's blood and horse's blood became 

 lake-colored when the fresh blood was shaken with a definite amount of 

 turpentine containing ozone, each time ascertaining by testing the amount 

 necessary. He could then cause crystallization with alcohol (only in the 

 clog), or ether, or sodium sulphate, or by water extraction in a vacuum. 



Several times it has been observed, continues Preyer, that an addition 

 of certain neutral salts to bloods which can be crystallized hastens crys- 

 tallization. According to Bursy the salts favoring crystallization are in 

 the order of their value as follows: Sodium sulphate, sodium phosphate, 

 sodium acetate, potassium acetate, magnesium sulphate, and potassium 

 nitrate. Less energetic are potassium carbonate, potassium sulphate, 

 sodium borate, barium nitrate, and sal ammoniac. Sodium nitrate ap- 

 peared to hinder crystallization when the blood was alternately frozen 

 and thawed. Sodium chloride, ammonium nitrate, calcium chloride, and 

 alum were without effect. For the production of crystals on a large scale 

 the addition of salts is not to be recommended, because of the introduction 

 of such foreign substances. Only chloride of sodium seems to be of value 

 in the isolation of the corpuscles according to Hoppe-Seyler's method. 



