1807. ^ET. 29.] PEOFESSOK DAVY. 347 



' Potagen certainly sublimes unaltered at a tem- 

 perature below red heat. It is twenty times lighter 

 than mercury.' 



On November 13 he wrote to his friend Mr. Pepys: 



I have decomposed and recomposed the fixed alkalies and 

 discovered their bases to be two new inflammable substi- 

 tutes very like metals, but one of them lighter than ether 

 and infinitely [more] combustible ; so that there are two 

 bodies decomposed and two new elementary bodies found. 



The Bakerian lecture was read on November 19, 

 only four days before Davy was obliged to take to his 

 bed by illness. The first sketch of this famous paper 

 was thus made in the Laboratory Book : 



6 The substance is analogous to some of those im- 

 agined to exist by the alchemical visionaries. 



' Possessing all the physical properties of metals ex- 

 cept high specific gravity, it seems to combine with all 

 of them, and form with them truly metallic amalgams ; 

 but in all cases it is capable of being separated from 

 them by its greater facility of oxidation.' 



Then he gives the action on water and ice. 



The theory of its operation upon water is extremely 

 simple. 



3. 'When,' he says, 'the peculiar substance was 

 brought in contact with a thin piece of phosphorus and 

 pressed upon, there is a considerable action.' 



4. ' When it was brought in contact with sulphur in 

 fusion in tubes filled with the vapour of naphtha, they 

 combine with varied ignition.' 



5. ' The new substance produces some beautiful re- 

 sults with mercury.' 



