§0 On the Decomposition of the Alkalis. 



of seeing the new metal obtained from potash, 1 repeated, at 

 their chemical laboratory, the experiment of Messrs. Gay 

 and Thenard, in presence of the governor to the pages, 

 -M. d'Assigny. 



'* The apparatus is equally simple with that for the de- 

 composition of water by means of iron, and every thing 

 proceeds in the same way as in this last experiment. We 

 put into a gun-barrel a quantity of iron filings sufficient to 

 fill that part of it which was inserted in the furnace: 

 caustic potash was introduced into one of its ends not in- 

 serted in the furnace, and the extremity was luted ; a tube 

 of safety Was adapted to the other extremity of the gun- 

 barrel, and a strong heat was then applied. 



" The furnace I used upon the occasion was 25 centime- 

 tres in tliamctcr, with double blast bellows. While the fur- 

 nace was strongly heated, I cooled with ice that part of the 

 gun-barrel which contained the potash : after continuing a 

 strong heat for an hour, I melted the potash by means of a 

 small portable furnace of sheet iron : the gun-barrel being 

 a little inclined towards the tube of safety, the fused potash 

 came in contact will) the iron : in an instant the hydrogen 

 of its water of crystallization was disengaged by the exj- 

 .tremity of the tube of safety, which was inserted under 

 water. 



" This disengagement of hydrogen is a certain mark of 

 the success of the experiment. When it slackens, from the 

 liquid potash having cooled the iron, we may remove the 

 , small furnace placed under the potash, which keeps it liquid, 

 and restore to the iron the temperature necessary for re- 

 ceiving new liquid potash. 



" This last effect is, as we see, completely similar to 

 what takes place in the decomposition of water ; for if 

 we pour too much water on the red-hot iron, the metal is 

 cooled, and the water passes off in vapour without being 

 decomposed. 



" Before fusing the potash in order to bring it over the 

 iron, 1 placed in ice that part of the gun-barrel to which 

 the tube of safety is adapted, and which serves as a refri- 

 gerant, 



« In 



