CHAPTER VIII 



THE GENERAL PHYSICAL PROPERTIES OF ALBUMINS (ACCORDING TO 



COHNHEIM) 



ALBUMINS, when in a dry state, appear as white or nearly colourless, 

 loose, voluminous, non-hygroscopic powders. Some albumins are known 

 to form crystals, but most are amorphous. Some are soluble in water, 

 while others dissolve only in salt solutions, in dilute acids, or alkalies ; 

 all are insoluble, however, in pure alcohol, ether, chloroform, benzene, 

 and all the other solvents in general use. In stronger solutions of 

 alkalies and acids and in glacial acetic acid they dissolve and undergo 

 dissociation. On being burned they leave behind the characteristic 

 smell of burnt hair ; they give rise to a voluminous slightly combustible 

 coal, and when burned completely, leave behind an ash in which are 

 found sulphuric acid derived from the sulphur of the albumin, and 

 usually several other inorganic elements such as calcium, and occa- 

 sionally phosphoric acid. 



Solutions of genuine albumins do not diffuse through animal 

 membranes or vegetable parchment, and belong therefore to Graham's l 

 class of colloidal bodies. What we have to understand under the 

 expression * colloidal ' has not yet been definitely settled. [The 

 author's views are given on p. 254.] Most people do not regard 

 the colloids as being in real solution, while Zsigmondy 2 has un- 

 doubtedly proved this to be the case. For albumins the question 

 has been definitely settled, because Sjoqvist 3 and Bugarszky and 

 Liebermann 4 have shown that albumin solutions conduct the elec- 

 trical current, and that they may act both as kations and anions 

 in other words that they without doubt form solutions which 

 obey the laws formulated by van 't Hoff. The albumins are indeed 



1 Th. Graham, Philosophical Transactions, 151. I. p. 183 (1861). 



2 R. Zsigmondy, Zeitschr. f. physik. Ghem. 33. 63 (1900). 



3 J. Sjoqvist, Skandinavisches Arch. f. Physiol. 5. 277 (1894). 



4 St. Bugarszky and L. Liebermann, Pflugers Arch. f. d. ges. Physiol. 72. 51 

 (1898): 



252 



