071 Sir H. Davy's Safe-lamp fur Mines. \9\ 



and then state those which I made. I should perhaps have 

 rather £;iveii the credit of these experiments to Mr. Rvaii, as it 

 seems it was he who first made them; but as he *'•' practised on 

 a lamp of onlv one inch diameter," he coincided with Mr. Holmes 

 in opinion that his trials were unfair ; and Mr. Holmes having: 

 procured a lamp hom Newman, the following experiments were 

 made by himself and Mr. Ryan, i)artiy at the gas-works in Dorset- 

 street, and partly at a chemist's, in the presence of four other 

 gentlemen. — 1 quote Mr. Holmes's words: 



" I tried it first over a small gas tube, with coal-dust and 

 powder, which ignited the gas outside; next with coal-dust alone, 

 which after repeated trials produced the same results, and left 

 an inflammation at the end of the tube." 



" On inverting a teacup over the cylinder so as to produce 

 a slight compression of the gas, it exploded from coal-dust se- 

 veral times." 



" We then went to a chemist's and forced some gas from a 

 bladder against one side of the cylinder, while gas from another 

 bladder was gently pressed on the oppovsite side : in a short 

 time the gas on the outside inflamed ; — this { compare to a 

 blower, although the power we were able to use was very in- 

 ferior to what would be given by the velocity of a blower under 

 ground." — " I found that the flame of the wick would not pe- 

 netrate the gauze cylinder, but the inflammation of the gas 

 would, when acted upon by a strong current of air." 



I shall now state my own experiments: — I suspended the safe- 

 lamp in tlie centre of the lanthorn, at about two inches from the 

 bottom, the fom- bottom apertures and the top of the lanthorn 

 being open — I then forced coal-gas, from a bladder, with all tlie 

 violence I could into the lanthorn through one of the lowest side 

 apertiu-es, an assistant at the same time throwing in atmospheric 

 air from another bladder, through the middle aperture, on the 

 opposite side, the other lateral apertures being closed. In a few 

 seconds, about two inches of the wire gauze !)ecanie red hot, and 

 by continuing the blast from each bladder it rose almost to wiiite- 

 ness, the heat being greatest at the side opposite the jet of at- 

 mospheric air. — At this point the exterior gas exploded. In a 

 former experiment of the same kind, in which the heat of the 

 wire was not raised above a low red heat, no explosion ensued. 



Mr. Holmes says he " cannot find that even this distinguished 

 chemist" (Sir M. Davy) "has been able to explain why flame 

 will not flow through small apertures." 



Mr. Holmes cannot have taken much pains in his search; for 

 in the first part of the Philosophical Transactions for the present 

 ^car, at page I 17, Sir Humphry says as follows : 



" If a i)icce of wire-gauze sieve is held over a flaine of a Uinip 



or 



