44 CYANAMID — MANUFACTURE, CHEMISTRY AND USES 



NATURE OF PRODUCTS FORMED IN SOU AT ORDINARY 

 TEMPERATURES. 



The formation of dicyandiamide is always accelerated by the 

 action of heat, whether in solutions of cyanamide, or in solu- 

 tions of cyanamide treated with lime, ammonia or other weak 

 bases. Since there is no formation of dicyandiamide when 

 cyanamide is heated with soil, as shown in the experiment on 

 page 43, there will evidently be none formed at ordinary tem- 

 peratures. This is verified in the following two experiments. 



Four kg. of soil in a balloon flask was sterilized on three 

 successive days by heating for an hour each day in an auto- 

 clave at ioo° ; then was introduced into the flask 800 cc. of a 

 solution containing 4.2 per cent, cyanamide. The flask was 

 stoppered and kept in a thermostat at 25° for 18 days. After 

 agitation with 3,200 cc. water for an hour, and filtering with 

 suction, total nitrogen and cyanamide nitrogen were deter- 

 mined. The results were as follows : 



Grams 



Initial nitrogen 2.492 



Nitrogen absorbed in soil i- 154 



Nitrogen in solution as cyanamide 0.671 



** " not cyanamide 0,667 



" "as dicyandiamide none 



After the removal of the cyanamide, and concentration on the 

 water bath, addition of nitric acid produced an abundant pre- 

 cipitate of nitrate of urea, which on recrystallization showed a 

 melting point of 140°. This experiment shows that under 

 sterile conditions the product of cyanamide conversion is prob- 

 ably entirely urea. 



Under natural conditions, there is little doubt but that the 

 urea is rapidly converted in the soil into ammonium com- 

 pounds. It was desirable therefore to learn how closely the 

 action of cyanamide resembled that of ammonium carbonate 

 in the soil. In a balloon flask containing 11 kg. of soil was 

 added 200 cc. of solution containing 4.2 per cent, pure cyana- 

 mide; and in another flask with 11 kg. of soil was added 200 

 cc. of solution containing 9.6 per cent, ammonium carbonate, 



