48 CYANAMID — MANUFACTURE), CHEMISTRY AND USE:S 



INFLUENCE OF ELECTROLYTES. 



To determine the effect of the presence of various reagents 

 on the course of the conversion, an experiment was made with 

 solutions of cyanamide in balloon flasks without addition of 

 soil, but with various electrolytes. The concentration of 

 cyanamide in the solution was 0.554 per cent. ; the other reag- 

 ents were in the proportion of two equivalents to one 

 cyanamide. The following table shows the amounts of 

 cyanamide remaining in solution. 



554 mg. cyanamide plus 

 After — c'a(OH)2 KOH HNO3 KNO3 



— weeks 554.0 557.0 556.0 451.0 558.0 



3.3 weeks 554-0 413.0 420.0 254.0 422.0 



8,3 weeks 554.0 369.0 382.0 — 369.0 



13.3 weeks 554.0 331.0 340.0 — 303.0 



28.3 weeks 554-o 182.0 trace — trace 



The very slow course of the reactions as compared with 

 the action of soil shows that it is probably not the soluble 

 salts in the soil that are responsible for the hydrolysis of 

 cyanamide but the solid soil particles. 



This confirms the conclusion drawn on page 42. 



NATURE OF EFFECTIVE SOIL CONSTITUENTS. 



In order to determine whether the conversion of cyanamide 

 is caused by the gross solid particles of mineral matter in the 

 soil, or whether it is due to colloids, or various organic debris, 

 the following experiment was .made. Soil was allowed to 

 stand a week in contact with concentrated hydrochloric acid, 

 and was then washed free of acid. A portion of soil so 

 treated was saturated with sodium carbonate solution and 

 then washed free of alkaline reaction. A fresh portion of 

 soil was calcined by heating in a combustion furnace in a 

 current of oxygen until carbon dioxide no longer escaped. 

 These samples were treated with cyanamide solutions as in 

 previous experiments, with the following results: 



