HEMOGLOBIN 471 



Haemoglobins differ greatly from one another as regards their 

 solubilities. Preyer 1 states that the haemoglobin of the ox becomes 

 fluid on being exposed to the air, while the haemoglobin of the squirrel 

 is only soluble in 597 parts of water, and that of the raven is hardly 

 soluble at all in cold water. The solubilities are greatly increased by 

 warming the solutions : dog's haemoglobin at 5 is only soluble to the 

 extent of 2 parts in 1 00 of water ; while at 18, 12 to 15 parts are 

 dissolved. Reduced haemoglobin is always more soluble than is oxy- 

 haemoglobin. Haemoglobin resembles albumins, as far as salting out is 

 concerned, i.e. it is not salted out by sodium chloride or magnesium 

 sulphate from neutral solutions, but is salted out by a saturated 

 magnesium sulphate + sodium sulphate solution. Schulz 2 gives the 

 precipitation-limits for ammonium sulphate as lying between 6*5 and 

 nearly completely saturated solutions. 



Oxyhaemoglobin is an acid according to Kiihne 3 and Preyer, 4 

 and methaemoglobin is also an equally strong if not stronger acid 

 according to Hoppe-Seyler, Menzies, 5 and Jaderholm. 6 Haemoglobin 

 is not acid. A precipitation by means of acid is not possible, as 

 haemoglobin is decomposed by extremely small amounts of acid. 



The coagulation-temperature of haemoglobin is 64 according to 

 Preyer ; 7 but haemoglobin becomes gradually decomposed if it be 

 kept for some time at 54. When quite dry, haemoglobin may be 

 heated for a long time without becoming denaturalised, but oxy- 

 haemoglobin is very apt to become converted into methaemoglobin. 

 Alcohol denaturalises pure haemoglobin only slowly, which, again, may 

 be due to all salts having been removed by repeated recrystallisation. 

 Haemoglobin crystals pass into pseudomorphoses when they are 

 treated with alcohol (Preyer 7 and Nencki 8 ) ; see below. Even before 

 alcohol has completely denaturalised haemoglobin it alters the dissocia- 

 tion of Oxyhaemoglobin, rendering it more like methaemoglobin. 9 It is 

 therefore important not to use alcohol in preparing crystals. 10 



Haemoglobin, being composed of an albuminous radical and a non- 

 albuminous iron-containing nucleus, it is very interesting to note how 



W. Preyer, Die Blutkristalle, Jena, 1871, p. 54, 



P. N. Schulz, Zeitschr. f. physiol. Chem. 24. 449 (1898). 



W. Kiihne, Virchow's Archiv, 34. 423 (1865). 



W. Preyer, Zentralb. /. d. med. Wissensch. 1867, No. 18. 



J. A. Menzies, Journ. of PhysioL 17. 402 (1895). 



Axel Jaderholm, Zeitschr. f. Biol. 2O. 419 (1884). 



W. Preyer, Pfliiger's Archiv, 1. 395 (1868). 



8 M. Nencki, Schmiedeberg's Archiv f. experim. Pathol. und Pharm. 20. 332 (1885). 



9 A. Lowy, Zentrcdbl.f. PhysioL 13. 449 (1899) ; G. Hiifner, Arch. f. (Anat. und) 

 PhysioL 1901, Suppl. p. 187. 



10 G. Hiifner, Arch. f. (Anat. und) PhysioL 1901, Suppl. p. 187. 



