BLOOD ,275 



average diameter commensurable with the mean 

 .wave-length of light. 1 Under the influence of 

 electrolytes (the salt solution) the particles 

 aggregate to larger and larger masses. When 

 these molecular aggregates attain a certain size 

 the fluid condition is no longer possible; this 

 would follow immediately from Graham's ob- 

 servation that actual coagulation is preceded by 

 a continuous increase in the viscosity of the liquid. 

 The following conditions determine this generic 

 action of salts as coagulants, as distinguished 

 from any specific chemical action. 1. The point 

 at which coagulation appears is determined by 

 the concentration of the solid in the colloidal mix- 

 ture, and the temperature, molecular concentra- 

 tion (gram-molecules per litre), and nature of 

 the electrolytes present. 2. The concentration 

 necessary for coagulation is lowered by a rise of 

 temperature, or by an electrolyte. 3. The coagu- 

 lative energy of electrolytes as measured by the 

 number of gram -equivalents per litre necessary 

 to produce coagulation is determined almost 

 solely by the nature of the metal of the salt ; 

 and among the metals themselves it is deter- 

 mined by the valency of the metal. 2 



1 PICTON and LINDER: Transactions of the Chemical 

 Society, 1895, lxvii, ( p. 63. 



2 HARDY : Journal of Physiology, 1899, xxiv, pp. 181-183. 



