1909.] MUNROE— DETONATION OF GUN COTTON. 71 



in the ascending order of the percentage of water present in the 

 priming blocks, although of necessity the experiments were made on 

 the primers as taken from the water and containing varying quanti- 

 ties of this substance. 



The results show that detonation was effected in every case in 

 which the primer contained less than 12 per cent, of moisture, but 

 that this also occurred in experiments number 7, 13 and 17, in 

 which the primers contained 12.77, 14.09 and 15.13 per cent, of 

 water respectively. These irregularities may be explained by the 

 irregularity of absorption of water by these blocks, owing to a lack 

 of regularity of porosity in them, for we can readily understand 

 that if the centers of these blocks, about the detonator holes, were 

 more highly compressed and therefore denser than a portion of the 

 remainder of each block, while the total water absorbed by the block 

 would be represented by the percentages given, yet the center might 

 remain dry enough to respond to the effect of the detonation of the 

 mercuric fulminate in the detonator, and thus determine the detona- 

 tion of the whole primer and also of the wet gun cotton block with 

 which the latter was in contact. This criticism may also apply in 

 a reverse manner to the primers containing less than 12 per cent, 

 of water, but the likelihood of such an excess of water about the 

 detonator hole as to prevent the detonation of the primer becomes 

 the more remote the less the total percentage of water present. It 

 is true that these vagaries may have sometimes been due to varia- 

 tions in the detonators used, but this factor was eliminated in these 

 experiments, so far as seemed possible, by previous severe tests of 

 the detonators. Admitting all of these possibilities, it would still 

 seem reasonable to conclude from these experiments that primers 

 containing less than 12 per cent, of water, when fired by means of a 

 detonator containing 35 grains of mercuric fulminate may be relied 

 upon, so far as the moisture content is concerned, to detonate wet 

 gun cotton with which they are in contact. 



The George W.\shixgton Uxr'ersity. 



