324 CHEMISTRY OF THE PROTEIDS CHAP. 



albumin, becomes once more colloidal. That no difference exists 

 between colloids and electrolytes, or, to put it differently, that colloids 

 are electrolytes under special conditions, was first pointed out by the 

 author, 1 and also in this book (p. 268). Ramsden is further of the 

 opinion that fibrin and fibrinogen have the same coagulation-tempera- 

 ture (see p. 382). 



With the exception of the neutral salts used in the salting-out 

 process, all agents causing precipitation lead to denaturalisation. But 

 even with the neutral salts, according to Spiro, 2 a change is said 

 to occur spontaneously although very slowly, but this by no means 

 bears out the author's experience, for egg-albumin crystals may be 

 kept unchanged for years, provided the ammonium sulphate solution 

 is perfectly neutral and saturated; the glass vessel lined with a 

 high melting paraffin, and the access of air carefully prevented. 



SOME PROPERTIES OF COLLOIDAL ALBUMINS 



1. Formation of Crystals 3 



Many albumins are known in a crystalline state, the crystals 

 occurring either naturally or having been made artificially. To the 

 naturally occurring crystalline albumins belong most of the phyto- 

 globulins, which are stored either as such, or in the form of their salts 

 in the seeds of plants, and also the vitellines in the eggs of fish. 

 Crystalline albumins have been prepared by artificial means from the 

 egg-white of the hen and other birds, from the blood of the horse and 

 the rabbit, and from the milk of the cow ; crystalline globulins have 

 been obtained from the white of the hen's egg, from Bence Jones' 

 albumin ; while crystalline proteids are represented by haemoglobin, 

 haemocyanin, and the phyko-erythin of algae ; and, finally, crystalline 

 peptones by glutokyrin (see p. 200). 



The long-known crystallisation of haemoglobin and the preparation 

 of edestin and other phytoglobulins by Osborne does not differ 

 principally from other kinds of crystallisation. 



It is a different matter with the crystallisation of albumins from 



1 Mann, Physiological Histology, pp. 45, etc. 



2 K. Spiro, Hofineister's Beitrage, 4. 300 (1903). 



3 F. N. Schulz, Die Kristallisation von Eiweissstoffen, Jena, G. Fisher (1901), gives 

 a good review of the literature dealing with albumin crystals. 



