250 Dr. J. Haldaue. An Enquiry into the [Jan. 24. 



In a paper read before tlie British. Association in August of the 

 present year* I expressed the opinion that black-damp is chiefly 

 nitrogen, and does not contain more than from 10 to 20 per cent, of 

 carbonic acid. One of the grounds for this opinion was the fact that 

 the symptoms and the action on lamps described as produced by 

 diluted black-damp do not correspond with those produced by 

 mixtures of carbonic acid with air. 



Through the kind co-operation of Mr.W. N. Atkinson, H.M. Inspector 

 of Coal Mines, I have lately had the opportunity of making observa- 

 tions on concentrated black-damp from two pits, the first being in a 

 fiery and the second in a non-fiery district. These two pits were 

 selected by Mr. Atkinson as affording characteristic specimens of 

 black- damp. In each case the gas was obtained from unused work- 

 ings through an iron pipe inserted through a stopping. On turning 

 fche tap with which the pipe was provided, the black-damp issued in 

 an abundant stream. 



Specimens were collected in the following manner : A short piece 

 of rubber tubing was attached to the tap by means of a cork perfo- 

 rated by glass tubing. The other end of the rubber tubing was 

 attached to another doubly-tubulated cork, which was fitted into a 

 small glass bottle. The second tube of this cork was connected by 

 rubber tubing with a small syringe, provided with valves arranged 

 for aspirating through the bottle. With the help of the syringe, the 

 bottle was washed out with about twenty times its volume of gas 

 from the tap, and then, while held mouth upwards, at once closed 

 perfectly air-tight by forcing into it a cork which had been previously 

 boiled in somewhat soft paraffin wax. I adopted this method owing 

 to the impossibility of using naked lights in a fiery mine for the pur- 

 pose of sealing up specimens of gas in glass tubes. 



Podmore Colliery, Staffordshire. 



An ordinary locked safety-lamp held under the tap was at once ex- 

 tinguished when the black-damp was allowed to issue, as was a 

 Clowes hydrogen lamp. Two other safety-lamps, which had been 

 put down or hung up a few yards away, were also extinguished 

 while the specimens were being collected. I was provided with one 

 of the small electric hand-lamps made by the Li fch anode Company, 

 which afforded an excellent light, so that the loss of the oil lights 

 caused no inconvenience. After the specimens had been collected,, 

 the tap was arranged so as to enable me to inhale the black-damp as 

 it issued, without dilution. I inspired from the tap and expired 

 through the nostrils. The sensation produced at the back of the 

 mouth was identical with that produced by air containing 8 or 10 pep 

 * An abstract oi* the paper appeared in the " Times " of August 18, 1894. 



