358 Mr. W. Galloway on the Influence [Mar. 2, 



and the Gas evolved from Blowers and by Boring into the Coal itself," 

 printed in the Journal of the Chemical Society, September 1874. 



Composition 

 in 100 parts. 



Marsh-gas 94*78 



Hydride of ethyl 0-90 



Carbonic anhydride 0*72 



Nitrogen 3*60 



100-00 



Although I was satisfied after this with the correctness of my hypo- 

 thesis in regard to mixtures of air, firedamp, and coal-dust, I could not 

 consider this form of the experiment to be quite satisfactory ; for it was 

 always possible that the coal-dust, in falling through the branch D, might 

 diminish the quantity of air sufficiently to enable it to form an explosive 

 mixture with the constant quantity of gas entering the apparatus. 



On the 4th of December last a serious explosion occurred in New Tre- 

 degar Colliery, and on the 6th two others followed, in Swaithe and Llan 

 Collieries. I made an official investigation into the circumstances attend- 

 ing the explosion in the last-mentioned colliery, and was fortunate enough 

 to be able to visit the workings within two and a half hours after its 

 occurrence, when the ventilation was only partially restored. At that 

 time the air in all the unventilated parts of the workings near the level 

 in which the explosion had taken place (as far as they could be explored 

 with safety) was so charged with coal-smoJce, soot, and other products of 

 the imperfect combustion of coal, that it was difficult to distinguish 

 objects two or three feet distant. 



During this and subsequent visits to these workings, I ascertained that 

 the floor of the level already referred to was covered with a layer 

 of dry coal-dust, mixed with small pieces of coal and stone, throughout 

 its entire length (130 yards); that for about 50 yards next its inner end 

 the ventilation of the level itself, and of the working-places branching 

 from it, depended almost, if not altogether, on a convection-current and 

 diffusion; and that firedamp was given off occasionally by the coal and strata 

 at the face of the level, and in two other places 50 or 60 yards further 

 out, in sufficient quantity to form small explosive accumulations. It 

 was asserted, moreover, that no accumulation of explosive gas was known 

 to "exist anywhere in, or near, this part of the workings an hour before the 

 accident; and as there were naked lights in each of the working-places, 

 an explosive accumulation which might be formed in one of them could 

 not find its way into any of the others without passing one of these 

 lights and being ignited by it. It was impossible, therefore, that a large 

 accumulation of gas could have been formed within the hour which pre- 

 ceded the explosion. 



On the other hand, there were traces of coked coal-dust on the timbers, 



