Royal Society, 387 



t)f combination wliich he had laid down. These laws (to repeat 

 them) are tlie following : 



*' 1 . That the sulphuret of any metal, when oxydated, is to- 

 tally changed to a neutral snlphat. 



" 2. That in every sulphat the oxygen helonging to the base 

 equals half the weight of the sulphur in the acid. 



"3. That in every compound of an acid and a base, the oxy- 

 gen of the acid equals that of the base multiplied by some inte- 

 gral number. To this mav be added the other law of all che- 

 mical combination (which is entirely adopted by the author) 

 namely, 



"4. That wh.ere two bodies unite in different proportions, if 

 the quantity of one of them be assumed as a fixed number, the 

 proportions of the other body are in the simplest ratio to each 

 other, being produced by multiplying the lowest proportion by 

 some integral number." 



[To be continued.] 



LXXI. Proceedifigs of Learned Societies ^ 



ROYAL SOCIETY. 



Nov. 9. -I HIS Society again assembled after the long vaca- 

 tion; the Right Hon. Sir Joseph Banks, Bart. President, in the 

 chair. 



A very important paper by Sir Humphry Davy was read, On 

 the Nature of the Fire-damp in Coal-mines, and the Means of 

 preventing its Explosion. 



In this paper Sir H. Davy describes a very simple lantern, 

 which he calls the Safe Lantern, for preserving the lives of colliers 

 in mines liable to explosions from the fire-damp. 



By various chemical experiments Sir H. Davy ascertained that 

 the fire-damp is the least combustible, and least expansive in 

 combustion, of all the inflammable gases ; and that explosive 

 mixtures of fire-damp have their explosive power destroyed by 

 small admixtures of azote and carbonic acid : and likewise that 

 explosions from the fire-damp are incapable oS passing through 

 small glass or metallic tubes. 



On these principles his lantern is founded, which is an air-tight 

 apparatus having small air tubes below, through which an ex- 

 plosion cannot pass; and a chimney above, in which the admJK- 

 tuic of azote and carbonic acid always prevents the possibility 

 of explosion. 



The candle or wick in burning forms the quantity of azote and 



carbonic acid necessary to lower explosive mixtures, should thev 



B b 2 exist 



