1815.] Carluretcd Hydrogen Gas in Coal-Mines. S35 



hydrogen, or inflammable gas, in coal-mines, before it can do 

 them any injury. For this purpose they make use of the smell and 

 the sight simply, and the changes induced on the top of a burning 

 candle. 



A tabular body of mist-like gaseous matter is sometimes observed 

 under the roof of tlie mine, and every motion communicated to ' 

 the air gives it a corresponding one. Miners have reasons, deduced 

 from dear-bought experience, to suspect the inflammability of a 

 body presenting tliis appearance. Such a body, however, docs not 

 always possess iliis property : for it may consist of a mixture of 

 carbureted hydrogen gas and the vapour of water, which on enter- 

 ing tiie mine ascends to the roof, and remains there till it is dis- 

 placed by a current of air, or accidentally set on fire by the miners; 

 or it may be the tobacco-smoke of the hewers and the vapour of 

 water which proceeds from the breath and bodies of the hewers, 

 and the persons employed to remove the coals ; and which, along 

 with the tobacco-smoke, is dispersed through the air by the people 

 at work, but which during their absence ascends to the roof, and 

 collects into a stratum of vapour, so similar in appearance to the 

 mixture of gas and vapour, as not to be distinguished from it but by 

 the most experienced eye. In this view of the subject, this method is 

 fallible ; and as the carbureted hydrogen gas is very often pure, or 

 unmixed with any other gaseous matter, its body is not visible. 

 Hence in eiiher case a miner who trusts to his sight only will be 

 very often deceived. 



A miner who uses the smell leaves his candle in a working at a 

 sufficient distance from its forehead, and advances slowly towards 

 it; he then traverses the wot king in many directions; and if he 

 finds no smell indicative of the presence of the inflammable gas, he 

 brings his candle to the forehead. But pure carbureted hydrogen 

 gas is odourless, and of course when its presence can ht known by 

 the smell, it must be mixed with other kinds of gaseous matter. It 

 is said sometimes to have a t^ulphurcous odour. I have not, however, 

 been aide to detect it by this ; but I have often done so by an empy- 

 reumatic odour, which probably proceeds from a subtile oily sub- 

 stance that sometimes leaves the coal along with the gas. As car- 

 bureted hydiogen gas in coal-mines is often pure, its existence in 

 them cannot always be known by the smell. Neither the sight nor 

 the smell, therefore, are to be implicitly relied on; l)ut they are often 

 very useful ; for a man may be tiavelling through a mine hastily, or 

 inattentive to the state of the ciienlating air, with his head in a 

 mixtuie of iiiHan mable and common air, and his hands and candle 

 in the comm(>n air only, and be advised by the sip,ht or smell of the 

 presi-ncc of the inflammable air, before he accidentally elevates the 

 candle and sets it on fire. 



liut the miner can place the greatest reliance on certain changeu 

 induced by the infliunniable air on the top of a burning candle. 

 The n-iner'-i term of tlie candle-top will not 1 e understood witiiout 

 «□ explanation. It is that faintly luminous yellowisii-brown body 



