92 Kansas Academy of Science. 



two per cent, of gas; and that even this amount is recognized only 

 in case the observer has keen eyes. 



Tests have also been made to determine what, if any, gases could 

 be withdrawn from the coal-dusts by placing them under a nega- 

 tive pressure. The results so far are negative, though it is believed 

 that some coals would yield gases under such conditions. Gases 

 driven off from the coal by increases in temperature have also been 

 examined. The temperatures used were much below those used in 

 the manufacture of coal-gas, the idea of the experiments being to 

 determine what gases might be derived from coal-dust under such 

 an increase of temperature as might be found under certain condi- 

 tions in a mine; for instance, such as might be caused by the pas- 

 sage of a wave of compression of mine air into a blind passage. 



The examination of explosives has been confined thus far to the 

 black blasting-powder, which is the explosive most commonly used 

 in American coal-raining. Its composition is approximately — 



Sodium nitrate 73 per cent. 



Sulfur 11 



Charcoal '. 16 " 



It is well known that the gaseous decomposition products of 

 black powder contain carbon dioxid, nitrogen, carbon monoxid, 

 methane, hydrogen and sulfuretted hydrogen, and sometimes small 

 amounts of other gases, and that the combustible gases mentioneH 

 sometimes constitute a sufficient percentage of the whole gaseous 

 mixture to make this mixture combustible. It was thought that 

 this fact might have an important bearing on the subject, and a 

 series of experiments have been conducted for the purpose of de- 

 termining the gaseous products of the decomposition of black 

 blasting-powder as it is now manufactured and the conditions under 

 which large quantities of combustible gases are produced. 



Our search of the literature of the subject disclosed the fact that 

 no investigation along this line had been so conducted as to give 

 its results any considerable value. The best work on the subject 

 of black powder has been almost entirely confined to the study of 

 gunpowder, which consists of potassium nitrate, sulfur and char- 

 coal. Correspondence with the principal powder manufacturers of 

 this country and some of Europe showed only that little was known 

 of the action of black powder or of the conditions necessary to the 

 production of large quantities of combustible gases. It is generally 

 assumed that the substitution of sodium nitrate for saltpeter has 

 no other effect on the powder than to make it more susceptible to 

 damage by moisture in the air. This fact has prevented its sue- 



