298 CHEMISTRY OF THE PROTEIDS CHAP. 



Starke's explanation is impossible, but apart from the fact that neutral 

 salts do drive out carbon dioxide from solutions, we must remember 

 Pauli's work (see p. 285), and therefore arrive at the conclusion that 

 globulins will pass into solution only in the presence of free hydrogen 

 or by hydroxyl-ions, and that, after the union of these ions with the 

 albumin has taken place, the ' neutral ' electrolytes will greatly facilitate 

 the passing into solution of globulins, by establishing differences of 

 potential which will diminish the surface tension of the globulin 

 particles. 



Finally, the conception developed by the author in Chapter VI. 

 should not be lost sight of, namely, that amino-acids develop the 

 tendency of forming internal salts, and of becoming insoluble owing to 

 the loss of their electrical charge, whenever they are removed from the 

 influence of electrolytes or when they are in the presence of such 

 mixtures of electrolytes that the sum of the electro-affinities of the 

 amino-acids and the other salt-ions of one sign (negative or positive) 

 are balanced by the electro affinities of the ions of the opposite sign. 

 In either case the ionic dissociation of the solvent, for example, water, 

 must also be taken into account. 



7. The Formation of Irreversible Salts 



That salts of the alkalies and of magnesium give rise to reversible 

 salts has been explained on p. 280, while now the effect of the salts of 

 the alkaline earths calcium, barium, and strontium, and of the heavy 

 metals zinc, iron, copper, silver, mercury, and lead will have to be 

 studied. 



Spring, in a number of very important papers, has studied the be- 

 haviour of finely suspended particles, particularly in relation to various 

 electrolytes. 1 He objects to the view, first put forward by Barns 

 and Schneider, 2 that colloidal particles surround themselves by either 

 physical or chemical means with a definite water-jacket, because there is 

 no definite proportion between the amount of colloid which is precipi- 

 tated and the amount of electrolyte which has been added ; he points 

 out at the same time that the addition of electrolytes stops the 

 Brownian movement, shown by suspensions whenever flocculi are 

 formed. Spring also discovered that all plurivalent salts which 

 undergo hydrolysis give rise to colloidal solutions, as tested by 



1 W. Spring and de Boek, 'Colloidal Coppersulphide,' Bull, de la Soc. Chim. de 

 Paris, 48. 165 (1887); 'A Water-Soluble Manganese Oxide,' ibid. p. 170. Spring, 

 'The Influence of Electricity on the Sedimentation of Turbid Fluids," Bull, de I'Acad. 

 Roy. de Belg. [3] 35. 780 (1898) ; ibid. 1899, p. 300 ; ibid. 1900, p. 483. 



2 See Mann's Physiological Histology, p. 33. 



