8 



Infliience of Arsenic in Solls 



[Oct 



was probably diie partly to the sodium ion. As Lipman^ has noted, 

 there is a marked Stimulation of nitrification in soils when small 

 quantities of either sodium sulphate or sodium chloride are applied 

 to them. 



TABLE 4 



Data pertaining to nitric nitrogen produced in wo grams of soll containing dif- 

 ferent amounts, and different forms, of arsenic 



The influence of insoluble arsenic Compounds. The Com- 

 pounds used in the ammonification tests were employed for this 

 series : lead arsenate, Paris green, zinc arsenite and arsenic trisulfide. 

 In each case the quantity of the Compound taken was such as to give 

 equivalent amounts of arsenic. The results, reported as milligrams 

 of nitric nitrogen per 100 grams of soil, are given in Table 4. 



These results bring out some very interesting facts, which are 



3 Lipman : Centralbl. f. Bakteriol., 1912, xxxii, p. 8. 



