Dandeno — Relation of Mass Action to Toxicity. 439 



the function of certain of the mineral salts in the soil. Plow- 

 man* dealt with the question from the standpoint of elec- 

 tricity and magnetism, using plants growing in flowerpots. He 

 concluded that ionization of the soil bore directly upon growth 

 of plants. Cameronf deals with the same question mainly 

 from the point of view of soils and crops. Clark J pursued a 

 line of work similar to that of Stevens. 



It is not the intention to give a complete historical bibli- 

 ography of the subject, but rather to mention some of the 

 more prominent work done directly along this line in order 

 that correlation of data may be available. Due acknowledg- 

 ment will be made of the work of each in its proper relation 

 to this discussion. 



The aim of most of those authors seems to have been to 

 determine, for certain solutions, the concentration at which 

 organs or organisms would just live, or just not live. .Nothing 

 apparently is said as to whether quantity of solution had any- 

 thing to do with the life of the organism. Nor is anything 

 said of the question as to whether the shape of the vessel, or 

 the presence of foreign non-chemical bodies might have any 

 influence upon the action of the substance in solution. The 

 quantity of solution used was apparently considered of little 

 importance by some of those who made experiments along 

 this line, for little or no mention is made of quantity. Cam- 

 eron (Bull. 71) and Loew (1. a), however, are clear on this 

 point. 



The method of preparing solutions was in strict accord with 

 the plan of chemical equivalents, that is to say, the solutions 

 were so prepared and named that n stands for a gram-equiva- 

 lent per liter of solution in each and every case. The number 

 in the denominator of the fraction whose numerator is n, 

 denotes the concentration of the solution under consideration. 

 Where the acids or salts are monobasic, the gram-molecule is 

 the same as the gram-equivalent ; where the acid or salt is 

 dibasic, then one-half the molecular weight to a liter is the 

 gram-equivalent. It is not necessary to mention acids or salts 

 of other basicity, as the two mentioned are the only kinds 

 used in the experiments here described. In the case of the 

 so-called acid salt (NaHC0 3 ), one-half the molecular weight in 

 grams dissolved to a liter is the gram-equivalent per liter 

 solution, — exactly similar in concentration to that of the car- 

 bonate (Na 2 C0 3 ). This may seem unduly explicit on this 



* This Journal (4), xiv, p. 129, Aug., 1902. 



f(a) U. S. Dep. Ag., Bur. of Soils, Bull. 22, 1903. 



(6) Jour. Phys. Chem., viii, 1, Jan., 1904. 



(c) Bull. 71, U. S. Dep. Ag. This contains a particularly valuable dis- 

 cussion of the matter, Kearney being associated with Cameron in the work. 

 ^Bot. Gaz., xxviii, p. 409. 



