76 GENERAL CHEMICAL AND PHYSICAL CHARACTERS 



Hoppe-Seyler (Archiv f. pathol. Anat. u. Physiolog., 1864, xxix, 233) 

 states that the dry hemoglobin crystals of the dog are soluble in the pro- 

 portion of 2 per cent at 5. Schmidt and Bottcher (Preyer, Blutkrystalle, 

 loc. cit.) with an impure preparation found that water-free hemoglobin of 

 the dog was soluble in 12.2 parts per 100 at 18, and the dry crystals in the 

 proportion of 15.59 parts per 100 at 18. Lehmann (quoted by Preyer) 

 records that the impure dry hemoglobin of the dog is soluble in the pro- 

 portion of 0.4 to 3.1 per cent, and the solubility of guinea-pig crystals 1 

 part in 597, or 0.167 per cent. With the crystals of the horse Otto (Archiv 

 f. ges. Ph) r siologie, 1883, xxxi, 240) was unable to obtain concordant results, 

 but Hiifner and Biicheler (Zeit. f. phys. Chemie, 1884, vm, 358) found a 

 solubility of 2.614 per cent at 1 and 14.375 per cent at 20. Standing in 

 dilute alcohol renders the crystals less soluble (Preyer and others). 



THE QUANTITY OF WATER OF CRYSTALLIZATION. 



The percentages of water of crystallization given by different investi- 

 gators, and even those noted by a given investigator with hemoglobin of 

 a given species, show marked discrepancies. These differences are owing 

 chiefly to the use of impure substances, to differences in methods of drying, 

 and to certain difficulties incidental to accurate determinations. Schmidt 

 and Bottcher (loc. cit.) found 13.49 per cent of water of crystallization in 

 the crystals of dog's blood that had been dried by standing many days 

 over sulphuric acid. Lehmann (loc. cit.) found in air-dried crystals of guinea- 

 pig in two instances 19.9 per cent, and in others 15 per cent and 16 per cent. 

 Preyer (loc. cit.) notes that after the crystals of the dog's hemoglobin were 

 dried in the usual way, and then powdered and subjected to a temperature 

 of 100 C., they lost 4.17 per cent. This powder upon standing in a glass 

 case (not air-tight) for 3 days increased in weight 10.93 per cent, and when 

 dried again at 100 C. decreased in weight 10.71 per cent. Lehmann re- 

 corded figures for dry guinea-pig crystals which agree with these. At 15 

 they absorbed on an average 11.19 per cent of water in five experiments, 

 according to which the air-dried guinea-pig hemoglobin would still contain 

 10.06 per cent of hygroscopic water, while the air-dry dog hemoglobin 

 contains, according to Preyer's experiments, 9.67 per cent. Later Lehmann 

 found that the air-dry dog crystals (which, however, were not pure) lost in 

 weight in vacuo 9.79 per cent, and that the crystals dried in vacuum at 

 15 absorbed in 14 clays 9.54 per cent of water, so that the air-dried sub- 

 stance would contain 8.71 per cent of water. They lost 9.09 per cent in 

 weight at 120 C. Proyer states that his and Lehmann's figures agree very 

 well when one considers that Lehmann worked with impure material and 

 that he (Preyer) used a pure recrystallized substance. 



Hoppe-Seyler (Med. chem. Untersuch., 1868, Heft 3, 366; Chemischen 

 Analyse, 1883, 292) noted the following percentages of water in crystals 

 dried at 100 C. with the aid of an air-pump: Dog 3 to 4, goose 7, guinea- 

 pig 6, and squirrel 9.4 per cent, In another publication (Physiologische 

 Chemie, 1877, 377) his figures for guinea-pig and goose hemoglobins are 

 7 and 9.4 per cent, respectively. Otto (Zeit. f. physiolog. Chemie, 1882, 



