52 ESSAYS BIOGRAPHICAL AND CHEMICAL 



negative pole of mercury, amalgams were obtained, con- 

 taining the new metals barium and strontium ; while 

 from lime and magnesia, evidence was similarly obtained 

 that they consisted of metals, named by Davy calcium 

 and 'magnium.' On removing the mercury by distilla- 

 tion, white metallic residues were obtained, still containing 

 mercury, but oxidising rapidly in the air, to the respective 

 oxides. An account of these results was published in 

 1807 and 1808, in the Philosophical Transactions. 



In December 1808, the celebrated paper on the elemen- 

 tary nature of chlorine was read. Having failed to obtain 

 any other products than hydrogen and oxygen on passing 

 a current through an aqueous solution of muriatic acid 

 gas in water (why, is not so apparent, unless only dilute 

 solutions had been employed), Davy treated dry muriatic 

 acid gas with potassium. The gas was absorbed, yielding 

 -% of its volume of hydrogen. He concluded from this 

 that dry muriatic acid gas contained at least one-third 

 of its weight of water, and that it had not been ' decom- 

 pounded ' by the potassium. His first attempt, therefore, 

 was directed to obtaining really dry muriatic gas. For 

 this object, he heated dry muriate of lime with dry sul- 

 phate of iron, with phosphoric glass, and with dry boracic 

 acid ; but without any evolution of gas, although when 

 water was added to the ignited mass, quantities of 

 muriatic gas were liberated. After numerous attempts of 

 the same kind, during which the chlorides of sulphur and 

 phosphorus were discovered, these substances were them- 

 selves submitted to the action of potassium, but without 

 the formation of any gaseous product. 



In an appendix to these observations, which were pub- 

 lished as the Bakerian Lecture, Davy announces the view 

 that 'muriatic acid gas is a compound of a substance, 

 which as yet has never been procured in an uncombined 

 state, and from one-third to one-fourth of water, and that 



