1905] TRUE & OGLEVEE—TOXIC ACTION OF POISONS 15 
between the solution and the paraffin, the condition of the solution 
more nearly resembles the surface film. In this case this film surrounds 
the particles of submerged paraffin, and any properties found to be 
possessed by the surface of contact with the paraffin should be in a 
manner similar to those of surface films. However this may be, 
the surface of contact with the paraffin seems to be such as to bring 
about a condensation of molecules with a consequent removal of a 
_ portion of the poisonous substance from the free solution and a decrease 
of the poisonous properties of the solution. This happens, also, 
in the face of the fact that the paraffin floats and must condense 
the molecules in the upper part of the culture vessel. It might seem, 
therefore, that the surface portions of the solution should be markedly 
more toxic than the lower free portion. If this be so, the ions or 
molecules seem to be held so firmly by the adsorptive force that they 
are still in effect removed from the solution so far as the roots are 
concerned. 
AMOUNTS OF TOXIC SUBSTANCE REMOVED FROM THE FREE SOLUTION 
BY ADSORPTION. 
The results seen in the tables above given seem to show that 
solid bodies are capable of adsorbing molecules or ions of toxic 
compounds, holding them so closely that in effect they are removed 
from the solution. We see many cases in which the growth rate is 
so far accelerated by the presence of the adsorbing solid as to lead 
one to infer that a very considerable portion of the toxic agent may 
be adsorbed. In cases it is observed that reduction has so far taken 
place as to practically relieve the solution of its toxic properties. 
In some instances the solution, decidedly toxic without the solid, 
becomes capable of supporting a more than normal growth in the 
presence of the solid. Here, an abnormal acceleration replaces a 
marked retardation, judged from the growth rate made in the dis- 
tilled water check culture. Such instances are seen in mercuric 
chlorid, os 
20,000 
solid amounting to an average of 2™™. When sand is added, the 
acceleration is so great as to bring the average growth rate in twenty- 
four hours to 16™™, 4™™ more than in the control culture. In the 
case of silver nitrate a number of instances of this sort occur. In 
. A retardation is seen in the culture lacking the 
