1908.] Experiments with Calcium Cyanamide. 



657 



The sulphide and phosphide detected doubtless arise from 

 traces of sulphate and phosphate present in the limestone 

 originally employed in the manufacture of the carbide. 



(3) In testing the effect of mixing cyanamide with other 

 manures, superphosphate alone need be considered ; it is the 

 only manure containing free acid in quantity (dissolved bones 

 being merely a form of superphosphate) so that with it the 

 maximum of chemical action would take place. Only the 

 water contained in other manures would react with the free 

 lime of the cyanamide ; further, it is with superphosphate that 

 mixtures would most usually be wanted in practice. 



An ordinary commercial grade of superphosphate was used, 

 and three separate lots, each of 2 cwts., were mixed with 11, 

 22 and 44 lb. of cyanamide respectively. The mixing was 

 done on the stone floor of a manure shed ; the manures were 

 weighed out, a layer of superphosphate was spread on the floor 

 and a shovelful of the cyanamide sprinkled over it, then 

 another layer of superphosphate and another shovelful of 

 cyanamide until the whole was mixed. The heap was then 

 broken down, passed through a sieve, the lumps reduced, and 

 the mixing and formation of the heap were repeated four times 

 to secure complete incorporation of the two manures. The 

 heap was then made up, thermometers were put into it and 

 read from time to time ; finally, on the next day, the mixture 

 was weighed and put up into bags, which were left in the manure 

 shed and examined at intervals. The mixing was a disagreeable 

 operation because of the light powdery nature of the cyanamide, 

 which rilled the air and hung about as a cloud for a long time ; 

 it was, however, during the weighing out and the first adding 

 of the cyanamide that this occurred, for as soon as it came in 

 contact with the superphosphate no further dust arose during 

 the rest of the process. 



During mixing the heap began to get warm, and with the 

 larger proportions of cyanamide began to steam a little ; 

 no offensive gases were, however, given off, so that it was only 

 the first dustiness caused by moving the original cyanamide 

 that caused inconvenience or unpleasantness. 



As will be seen from the temperature records a considerable 

 development of heat followed the mixing, due in the main to the 

 slaking of the free lime in the cyanamide and its reaction with 

 (3007) 2 T 



