on the Nature of certain Bodies. \\ 



exposure to the air, the operation proceeds with the greatest 

 tranquillity. No elastic fluid is given off from the potas- 

 sium ; it often appears covered with the olive-coloured sub- 

 stance, and as if it were evolving hvdroaen ; this must pass 

 through the fluid ; but even to the end of the operation, no 

 such appearance occurs. 



The cryslalllzed and spongy substance, formed in the first 

 part of the process, I am inclined to consider as a combina- 

 tion of ammonium and potassium, for it emits a smell of 

 ammonia when exposed to air, and is considerably liohier 

 than potassium. 



1 at first thought that a solid compound of hydrof^en and 

 potassium might be generated in the first part of this opera- 

 tion : but experiments on the immediate action of potassium 

 and hydrogen did not favour this opinion. Potassium, as I 

 ventured to conclude in the Bakerian Lecture for 1807 *, is 



very 



♦ MM Gay I.u=sic and Thenard seem to be of a difTcrent opinion. In tiie 

 Moniteur, to which I have so often referred, it is related, that these distin- 

 guished chemi.-ts, exposing hydrogen to potassium at a high temperature, 

 found tliat the liydrojfcn was absorbed, and that it formed ?. compound with 

 the potassium of a liglit gray colour, from which hydrogen was capable of 

 being obtained by the action of water or mercury. 



After a nimibcr of trials, I have not been able to witness this re=nlt. In an 

 experiment which I made in the presence of Mr. IVpys, and whicli I have 

 oficn repeated, and twice before a numerous assembly, in retorts of plate 

 glass, four grains of potassium were heated in fourteen cubical inches of pure 

 l)ydrogen. At first, while fumes arose and precipitated themselves in' the 

 neck of tlie retort. Wlien a considerable film of the precipitate had collected- 

 its colour appeared a bright gray, and after the first two or tiiree minutes, 

 it ceased to be formed. 



The bottom of the retort was heated to redness, when the potassium bco-an 

 to sublime and condense on the sides. 



The process was stopped, and the retort sulTercd to cool. The absorption 

 was not equal to a ijuarter of a cubical inch. When the retort was broken. 

 the gas in passing into the atmosphere, produced an explosion with most vivid 

 li}(ht, and white fumes. Tiic potassium remaining in the retort, and thai 

 whiili had sublimed, seemed unaltered in their properties. 



'the grayish substance inflamed by the action of water, but did not seem 

 to be combinaWe witli mercury. I am inclined to attrilnite its formation to 

 the agency of moisture suspended in the hydrogen, and to consider it as -.k 

 triple compound of potassium, cixvgcn, and hydrogen. 



/ When potassium is heated in a gas containing hydrogen, .ind from .^ to -^ 

 •f common air, it is formed in greater cjnanlilies, an<l a crust of it covers th* 



nu'tal 



