654 Experiments with Calcium Cyanamide. [feb., 



condition and the second dried in the steam oven. The 



nitrogen in each sample was then determined and the results 

 are set out in the following table : — 



Time of Exposure. 



Undried. 



Dried. 



Weight. 



Nitrogen 

 Per Cent, 

 on Original 

 Weight. 



Weight. 



Nitrogen 

 Per Cent, 

 on Original 

 Weight. 





Gram. 





Gram. 





Starting 



I * ooo 



I7'24 







After i week 



1-669 



16-87 



1 '231 



16*04 



2 weeks 



1 "734 



16-30 



1-240 



15-88 



„ 3 » 



1-793 



16-18 



1-259 



15-26 



„ 4 j> 



1-859 



I5-97 



1-269 



I5-77 



J5 5 3> 



2-234 



15-85 



1*289 



15-89 



„ 6 „. 



2*069 



16-17 



1-278 





„ 7 „ 



2-431 



16-24 



1-298 



15*13 



>■> 8 5) 



2-508 



l6"2I 



1-295 



14-92 



£ 9 » 



2 - 802 



15*75 



1 -296 



I4-52 



„ IO 



3-235 



16-03 



1-396 



14-69 



These results show that the first action of slaking the free 

 lime in the crude cyanamide takes place very quickly when the 

 material is exposed in a thin layer to an atmosphere saturated 

 with moisture, since the weight rises 67 per cent, in the wet 

 condition and 23 per cent, in the dry condition during the 

 first week's exposure. At the same time there is a slight loss 

 of ammonia, though this loss is almost covered by the experi- 

 mental error inherent in drawing small samples from a powder 

 of variable composition like cyanamide, the difference being 

 little greater than that found between consecutive samples 

 drawn for analysis from the original manure. 



With further exposure the cyanamide continues to absorb 

 water until in the end it runs down to a wet paste ; further 

 losses of ammonia in the wet state are, however, small, being 

 in the final sample only 7 per cent, of the total nitrogen with 

 which the material started. The weight after drying increases 

 but little in the latter part of the experiment, because the 

 main reaction causing an increase of weight — the slaking of the 

 free lime — is completed in the first week. The losses of nitrogen 

 in the dried sample increase steadily and amount to about 

 2 per cent, after the tenth week. These losses are due to the 

 volatilisation during the drying of any ammonium carbonate 

 that has formed. 



