x3 BOTANICAL GAZETTE [JANUARY 
It appears in general that the presence of a considerable body 
of certain insoluble substances in solutions of strongly toxic com- 
pounds, both organic and inorganic in their nature, be they electro- 
lytes or not, tends to decrease the toxic activity of the solutions in 
question. 
On the whole this ameliorating action is more clearly marked 
in case the poisonous solutions concerned are dilute solutions of 
strong poisons than when relatively concentrated solutions of weaker 
poisons are concerned. 
In general, filter paper and potato starch grains exert a more 
marked modifying action than dense sand, glass, and paraffin. 
A number of questions immediately arise concerning the relation 
in which the active ions or molecules stand to this phenomenon. 
It seems probable that no electrical phenomena are here necessarily 
concerned. In the case of electrolytes such a situation might be 
possible, but in thymol and resorcinol we have to do with electrically 
neutral bodies. _ 
A more satisfactory explanation seems to lie in another quarter. 
Chemists have long known that gases form a denser layer over the 
surfaces of the walls of containing vessels than in the free space 
away from the walls. Certain solids have the capacity of condensing — 
on their surfaces larger volumes of gases than others, seeming to — 
have specific properties in this direction. For example, platinum — 
in a finely divided form condenses many times its own volume of 
oxygen. A similar phenomenon has long been known in a practical 
way in the case of solutions. Many years ago it was noted that bone 
charcoal has the property of taking certain coloring bodies out of syrups, 
thereby clarifying the latter products. The investigation of this 
and similar phenomena has shown that molecules of many dissolved 
substances are attracted to the surface of charcoal, quartz, and filter 
paper, when these bodies are placed in these solutions, and in general 
the greater the state of subdivision to which these insoluble bodies 
are reduced, the more clearly may this condensation of molecules 
from the solution be seen. This process by which a layer of greater i 
molecular density is formed on the surfaces of solids immersed in __ 
solutions has been denominated by DuBots-REYMoND es (6 
Not all solids have been found to be Tg ete “t 
