THOMPSON AND LOMBARD. — NITROGEN IN CALCIUM CYANAMIDE. 2G9 



Time did not permit of making a combustion analysis to see how the 

 carbon checked up. This sample apparently contained very little free 

 carbon, for it was of a cream white color. 



Since calcium cyanamide was present in the powder distilled to the 

 walls of the furnace, when heated with carbon it should produce calcium 

 carbide with the evolution of nitrogen. In order to see whether this 

 actually takes place, 0.4 gram of the powder was mixed with 0.9 gram 

 Acheson graphite and heated in the vacuum furnace. The results are 

 the following : 



July 11. 



The temperature measured at 12.35 p.m., with the current in the 

 Wanner 6.1 units, was 1287° C. 



On opening the furnace after this run no white deposit was found on 

 the walls, and the material in the crucible seemed to be hardly changed 

 in appearance. It gave no test for carbide with an ammoniacal cuprous 

 chloride solution, nor for cyanamide with silver nitrate. It is to be 

 noticed, however, that a great deal more gas was evolved from this mix- 

 ture on heating than on heating a sample of carbide, fi'om which occluded 

 gases always escape. For example, in Experiment 15, on heating carbide 

 to 1450° C, these gases produced a pressure of 127 millimeters, which 

 is considerably less than the 195 millimeters produced from the white 

 powder and carbon at 1287°. It therefore seems certain that the large 

 amount of gas evolved in Experiment 14 was due to a chemical reaction 

 and not to occluded gases alone. A possible explanation of the absence 

 of carbide in the crucible is that some oxygen got into the furnace. This 



