THE GREAT LONDON CHEMISTS 49 



that on treating manganese dioxide with hydrochloric 

 acid, or as it was then called ' spiritus salis/ in a flask to 

 which a bladder had been attached, a ' yellow air ' filled 

 the bladder, which possessed a suffocating smell, which 

 bleached litmus paper and flowers, and which attacked 

 metals, even gold. He named this new gas ' dephlogisti- 

 cated marine acid/ imagining that the manganese had 

 deprived the marine acid of its ' phlogiston,' and that it 

 had consequently been converted into the yellow gas. 

 Count Berthollet, in 1788, prepared this gas, and on 

 saturating with it water cooled with ice, he discovered 

 that a solid crystalline hydrate separated from the water. 

 Having exposed a solution, thus obtained, to sunlight, he 

 noticed the evolution of oxygen, and he, therefore, con- 

 cluded that the dephlogisticated marine acid was in 

 reality a compound of marine acid with oxygen, since, 

 under the action of sunlight, oxygen was evolved, and 

 marine acid left. This idea, according to Berthollet, 

 readily explained the action of the solution of the yellow 

 gas on metals; for it might be supposed to give up to 

 metals its oxygen, and the metallic oxide would then, as 

 usual, dissolve in the marine acid. In consequence of 

 this observation, M. de Morveau, in conjunction with 

 Lavoisier, Berthollet, and de Fourcroy, in drawing up 

 their Meihode de nomenclature chimique, proposed for 

 the gas the name 'Oxymuriatic acid.' To follow the 

 further history of chlorine, it will be advisable to pause, 

 and consider Davy's researches on the^alkali metals. 



Before leaving Bristol, Davy had* begun experiments 

 with the galvanic battery. On reaching London, he con- 

 tinued his electrical work; and in 1807 he published a 

 remarkable paper on the 'Chemical Agencies of Elec- 

 tricity.' It had been shown that when the two poles of a 

 battery with platinum terminals were plunged into two 

 vessels of water, connected together by wet asbestos, or 



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