Biographical Memoir of Sir Humphry/ Davy, 21 



titles of carbon and hydrogen of which it is composed, and the 

 proportions by which its combination with common air produces 

 more or less violent detonations. He then examined at what de- 

 gree of heat combustion took place, and according to what laws 

 it is propagated. He observed that it could not take place in 

 tubes of small dimension, even when every circumstance was 

 favourable to its production, because the size of the tubes suf- 

 ficiently cooled the gas to prevent its combustion. He thence 

 concluded that by preventing the air from coming in a volume 

 on the wick, and causing it to enter by long and narrow aper- 

 tures, and only in suitable quantities to support the light, deto- 

 nation could not ensue, even though the proportions of the air 

 should be most favourable to produce that effect. 



He was thus led to construct a lantern, the communication to 

 the interior of which was through the intervals of numerous 

 concentric tubes, and which had a chimney covered with a plate 

 pierced with small holes, or formed of metallic gauze. This 

 first attempt did not give him satisfaction, but led to the con- 

 ception of something more perfect. He submitted solids to nu- 

 merous experiments, that he might seize the just degree of cool- 

 ing power which they possess, and discovered many physical 

 facts full of interest, among others the greater intensity of the 

 heat of flame, than even that of metal at a white heat. Thus 

 a wire of platina became red in a mixture, the combustion of 

 which was too slow to produce flame, — a surprising fact, for 

 which no explanation has been found. The result of all these 

 experiments was, that a metallic gauze may be formed, the 

 meshes of which may be of that precise diameter fitted to cool 

 the inflamed air which traverses them, and at the same time 

 prevent its combustion, and which may be permeable to air and 

 light without being so to flame. The invention therefore was 

 brought to the degree of simplicity necessary for the men to 

 whom it was destined, and formed consequently a complete so- 

 lution of the problem *. 



• On the Safety LAmp for coal-miners, and some researches on flame. 8vo. 

 London 1815. 



On the fire damp of coal mines, and on methods of lighting the mine so as 

 to prevent its explosion. Roy. Soc. Lond. 9th November 1815. Phil. Trans. 

 V. cvi. p. 1. Ann. de Chitn. et Physique., torn. L p. 136. 



