146 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



formation is — ±0.8 cals. Hence tetryl is an endothermic compound 

 and this explains in part the power of this explosive. It is easily 

 prepared by acting on methylaniline sulphate with mixed acids. It 

 appears at present to be used only in the manufacture of cordeaux 

 detonants. Many of the properties it exhibits tend to show it to be 

 well fitted for use in shell charges. We may note, however, that its 

 price, as well as that of the preceding explosive, is greater than that 

 of picric acid. 



