118 DAVY. 



opinions of all philosophers on the subject, that the 

 suspicion of those eminent men was well founded; that 

 the oxymuriatic acid is a simple substance, containing 

 no oxygen , that it unites with oxygen to form an 

 acid, which forms with alkalis the detonating salts 

 hitherto called oxymuriates, as being supposed to con- 

 tain oxymuriatic acid combined with alkaline bases ; 

 and finally, that with hydrogen it forms the acid long 

 and well known as the muriatic or marine. To the 

 oxymuriatic acid he gave the name of chlorine from 

 its green colour, and to common muriatic acid that of 

 hydrochlorine. The union of chlorine and oxygen he 

 calls chlorine acid, and its compounds, of course, chlo- 

 rates. This is justly reckoned one of the most impor- 

 tant of Davy's many brilliant discoveries. 



It remains to make mention of the valuable present 

 which this great philosopher offered to humanity his 

 safety-lamp. The dreadful ravages made on human 

 life by the fire-damp explosions that is, the burning 

 of hydrogen gas in mines had often attracted the 

 notice of both the mine-owner and the philanthropist. 

 Various inventions had been fallen upon to give light 

 in those recesses of the earth with so low a degree of 

 heat as should be insufficient to explode the gas. One 

 of them was a series of flints playing by machinery 

 against each other so as to give a dim light ; but this 

 had very little success ; it was clumsy, and it was not 

 effectual so as to cause its use by miners. The ventila- 

 tion of the galleries by furnaces and even by air-pumps 

 was chiefly relied on as a preventive ; but gas would 

 collect in spite of all preventives, and the destruction 

 of a hundred or more lives was not an unusual calamity. 

 Davy about the year 1815 turned his attention to the 

 subject, and after fully ascertaining that carburetted 

 hydrogen is the cause of the fire-damp, and finding in 

 what proportions it must be mixed with air in order to 

 explode (between six and fourteen times its bulk), he 

 was surprised to observe, in the course of his experi- 



