122 



Journal of Agricultural Research 



Vol. XVI. No. 4 



Table XI. — Percentage of nitric nitrogen formed in lOO gm. of soil containing 2 gm. 

 of dried blood and to which were added varying amounts and kinds of chlorids in equal 

 m,olecular proportions 



[The untreated soil is taken as loo per cent] 



Fraction of jnolecular weight in loo 

 gm. of soil. 



None 



1 56X10-7 



312X10-'' 



625X10-^ 



125X10-® 



25X10-5 



5X10-* 



iXic^3 



2X10-3 



4X10-^ 



Percentage of nitric-nitrogen formed in the presence of — 



This would be taken to indicate that the toxicity of the salt is due to 

 physiological action upon the bacteria and not the osmotic pressure 

 exerted by the several compounds. 



influence; of suIvPhates 



The compounds used in this series were the sulphates of potassium, 

 sodium, calcium, magnesium, manganese, and iron. The quantity of 

 the salt used in each case was such that equivalent quantities of sul- 

 phate in the various forms were added to 100 gm. of soil. It was also of 

 such a concentration, with the exception of the iron sulphate, that equal 

 molecular proportions of the various salts were added to 100 gm. of soil 

 The results, as averages of a number of closely agreeing determinations, 

 are given in Table XII. 



Table XII. — Percentage of nitric nitrogen formed in loo gm. of soil containing 2 gm. 

 of dried blood and varying amounts and forms of sulphates 



[The untreated soil is taken as 100 per cent] 



