PEOGRESS IN EXPLOSIVES GUTTMANN. 



291 



fested. Might I submit an old idea, which I base on some patents of 

 mine that have proved highly useful? An absorption tower retains 

 solid particles contained in a gas mixture, and also cools the latter 

 very efficiently, and one of the best methods for absorption has proved 

 to be the production of a fine spray or mist of moisture. It seems 

 quite feasible to utilize certain lengths of tunnel for the construction 

 of inverted absorption towers at intervals, and certainly at every 

 point where a side gallery runs into the main or haulage roads. So 

 much seems certain to me from the study of the results of past inves- 

 tigators that a small addition of coal dust will be found to promote 

 the explosion of poor gas mixtures, and that, therefore, a separation 

 of the dust from the gas will in some cases prevent an explosion. 



Lacking definite knowledge as to what renders an explosive safe in 

 fire damp, and how this is to be ascertained, it would be natural to 

 seek a solution in practical results. The sale of an article does not 

 always depend upon its real value, but very frequently on the way it 

 is advertised and pushed, whether it is made in the country of con- 

 sumption or not, whether it possesses disadvantages that render an- 

 other less efficient article a preferable one, etc. In spite of this it is 

 not unfair to assume that the statistics showing the quantities of 

 safety explosives actually consumed in a great coal-producing coun- 

 try like Great Britain have a real bearing on the question as to which 

 explosives have given a reasonable amount of safety. The report of 

 the inspectors of explosives for 1907 gives the following highly 

 instructive figures: Out of a total consumption of 7,764,122 pounds, 

 were used, of saxonite, 1,721,193 pounds, or 22.18 per cent, and of 

 bobbinite, 1,063,111 pounds, or 13.69 per cent. 



Saxonite contains a large percentage of nitroglycerin. Bobbinite 

 is a black powder mixture. 



From the inquiry on bobbinite "- the following table regarding 

 accidents in coal mines caused by various safety explosives in 1904 

 and 1905 is calculated : 



It will thus be seen that a black powder mixture like bobbinite, 

 which would not be licensed in any other country and be condemned 

 without trial, ranks second in consumption, being used to the extent 



' « Report of the departmental committee on bobbinite, London, 1907. 



