Dandeno — Relation of Mass Action to Toxicity. 451 



tion. When in liquid alone, radicles withstand barely 3 CC of 

 w/2048* solution, or 3/2048 cc per l cc of normal acid ; therefore 

 9/2048 represents the physical effect of the sand with the two 

 substances used. This is about 4:1, at or near the limit where 

 root tips just resist the acid and live. 



Similarly for KOH and JSTaOH, with the pea and the lupine, 

 the sand retards the action of 3/256 of l cc of normal KOH 

 near the resisting limit. For KOH and corn it is 3/128 of l cc 

 normal. 



The seedlings withstood relatively a very great concentration 

 of CuS0 4 when sand was present; actually ^/4096 (Table Ya) 

 as against not less than w/32768 without sand. This seems to 

 be due again to the presence of the non-chemical body. The 

 reason why the toxic action is so much reduced with this sub- 

 stance is probably because, as has already been mentioned, the 

 attractive force of the sand is constant, and requires satisfac- 

 tion ; therefore, in dilute solutions, where there is so much less 

 of the solute per unit of volume, the seedling would be relieved 

 of a large proportion of the harmful element. The actual 

 amount for this solute would be 3/4096 - 3/32768 = 21/32768 

 gram-ions of copper. This hindrance to toxic effect of the 

 solute is probably also due in some measure to the retarding 

 effect upon diffusion caused by the presence of the foreign 

 body. 



The suggestion which arises from this non-chemical action 

 of sand is that soils may hold mechanically a portion of a so- 

 lute, and may never give it up. It may be forced to liberate a 

 part of it by the application of another solute which might, in 

 part, satisfy the attractive force exerted by the particles of soil. 

 This may also account for the fact that a chemical analysis is 

 not always a final argument as to the fertility of soil. For 

 instance, suppose KN0 3 were applied in a certain quantity to 

 a pure sand, and plants be allowed to grow for a time in this, 

 it would be found that the plants had been unable to extract 

 all the KN0 3 ; but if another substance, say Ca(JS T 3 ) 2 , be then 

 applied, the amount of KN0 3 available might be increased, 

 though no chemical action take place. It is probably thus with 

 the whole subject of fertilizers. A substance may often liber- 

 ate an important element by taking its place mechanically in 

 the soil, though the substance which had been applied have 

 itself no fertilizing value. The writer is aware that many con- 

 sider a chemical analysis of soil a definite basis for a liquid 

 nutrient solution, and vice versa. Cameron. (Bui. 22, U. S. 

 Dep. Ag., p. 15), quoting Johnson, states: u The analysis of the 

 well water shows that a nutritive solution need not contain 



* Slight exceptions to this may be noticed as shown in Table II, but cal- 

 culations are made only from the most certain limits. 



