WALLACE 0. FENN 



589 



Extensive qualitative experiments of a similar nature have been 

 carried out by Reinders (10) and by Hofmann (11). Both agree 

 that particles of carbon are among those most easily adhering to 

 droplets of oil, chloroform ether, etc., but neither used quartz particles 

 for comparison. 



The theoretical distribution of solid particles between two liquid 

 phases according to the surface tension relations has been excellently 

 summarized by Thompson (12). In a general way it may be said 

 that in a carbon-oil-water system the lower the potential energy of 

 a carbon-oil surface, the greater the chance of the carbon being in the 

 oil, and vice versa. By collecting in the interface the oil-water surface 

 is reduced. Therefore, the higher the oil- water tension, other quan- 

 tities being equal, the greater the chance of the carbon being in the 

 boundary. By collecting in the interface the carbon decreases the 

 potential energy of the oil-water surface. This is presumably the 

 reason for the emulsifying power of lampblack on water-kerosene 

 systems reported by Moore (13). 



Although the more rapid ingestion of carbon by leucocytes could 

 not be predicted from the selective wetting of carbon by oil, phenol, 

 and chloroform drops^ the same principles of surface tension which 

 explain the inorganic phenomenon can be appHed to an explanation 

 of the biological fact. It may, therefore, be argued that carbon would 

 be taken up by leucocytes more rapidly than quartz, if the potential 

 energy of a carbon-serum surface were greater than the potential 



'The fallacy of predicting a surface tension of a particle in one medium from 

 its surface tension in another is shown convincingly by the behavior of particles 

 of manganese dioxide and manganese silicate. The former are taken up less 

 rapidly than the latter by drops of chloroform and paraffin oil, but about twice 

 as rapidly by sponge cells and in some experiments at least 20 times as rapidly 

 by rat leucocytes. 



