ON THE CRYSTALLOGRAPHY OF HEMOGLOBIN. 97 



by water heated to 30 to 40, and filtered, and the filtrate is collected in 

 a large cylindrical vessel standing in ice. A small measured portion of the 

 red solution thus obtained is gradually mixed during constant agitation 

 with small quantities of alcohol until a slight precipitate forms. This 

 determines how much alcohol may be added to the whole solution without 

 a precipitate appearing. A slightly smaller proportion of alcohol is now 

 added to the remaining filtrate and the mixture is placed in a cooling 

 medium. Even after a few hours the crystals separate in great abundance. 

 The crystals are, owing to the volume of water used, very easily filtered off 

 in the cold. They are then washed with cold water containing a little alcohol 

 until the filtrate yields only an insignificant cloudiness upon the addition 

 of acetate of lead or corrosive sublimate. The product yielded is a very 

 large one. The crystals may be purified by repeated washing by decanta- 

 tion until the wash-water does not become cloudy with bichloride of mer- 

 cury, acetate of lead, or silver nitrate. They are then nearly pure, and the 

 ash is free of phosphoric acid and consists of pure iron oxide. If this is not 

 the case, then they must be dissolved in warm water and recrystallized as 

 directed. At a temperature of less than the crystals can be dried in the 

 air without becoming decomposed. 



This method differs essentially from (V) only in that instead of defibri- 

 nated blood a diluted extract of the clot is used. But in this there is a great 

 advantage, because the crystals can be obtained pure very much more 

 easily and quickly owing to the very small quantities of serum albumin 

 that can adhere to them. Furthermore, the fluid, because of the lack of 

 serum albumin, filters more quickly. It will therefore be noticed that by 

 the coagulation of the blood, by the treatment of the clot with water, by the 

 freezing of the same, and by the longer interval from the time of bleeding 

 to the mixing with alcohol, the degree of crystallizability increases. Preyer 

 obtained larger crystals by this method than by any of the others. 



Of all kinds of blood, that of the horse, he states, is best adapted for 

 the production of very large quantities of pure hemoglobin. It is defibri- 

 nated and the corpuscles are allowed to settle in a high cylindrical vessel, 

 the serum is drawn off, and the corpuscles are frozen, etc. 



If crystallized hemoglobin is to be produced quickly from the defibri- 

 nated blood of the dog, it is best to mix the blood with its own volume of 

 distilled water, add 1.5 volumes of absolute alcohol to 4 volumes of the 

 mixture, and then place the solution in a cylinder in a cooling mixture. 

 After a few hours the fluid has changed to a crystal pulp. By frequent 

 washing, by decantation, or by centrifugalization with diluted alcohol (4 

 volumes of water to 1 volume of absolute alcohol), crystals are obtained 

 pure, but of course with great loss. This very convenient method has the 

 disadvantage that the corpuscles by their remaining longer in dilute alcohol 

 become difficult of solution in water. If the preservation of the normal 

 solubility is disregarded an abundant crystallization can be obtained at 

 8 to 10 from dog's blood by mixing 1 volume of fluid with an equal volume 

 of water and a little more than one-fourth of the whole volume of absolute 

 alcohol. The mixture in one case had formed a thick crystal pulp in 9 



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