J8 GASES ABSORBED BY CHARCOAL. 



under water, in a tube of one inch in diameter and fix inches 

 and yields a por- high, which was alfo filled with water. A part of the air 

 f°rb^d ah- ^vhfch wmc ^ tne ^ containe d was immediately developed, but I only 

 is a compound obtained about two inches, (they had, however, abforbed 



of azote and car- amon them near i y thirty-two inches). The reftored air was 

 bonic acid gafcs j ° J J 



found to be compoled ot carbonic acid gas and azote gas. In 



this operation a part of the air is fixed in the charcoal to be 

 embodied with it, and cannot be again diflodged but by em- 

 ploying fire. I believe thefe combinations frequently occur 

 in nature, and the great Newton fufpecled it. 



47th, I dried the pieces of charcoal which had been wetted 



by which it re- in the preceding experiment, in the air : I afterwards exa- 



benT ower. 01 " m ' ne( ^ them, by again heating them to rednefs in the fire, 



and placing them in the machine ; they abforbed the fame 



quantity of air as before. 



No water pro- _ 48th. I directed all my attention, as well after as during 



miction of £ the" t ' ie cour ^ e °f ^ e experiments on atmofpheric air, to fee if 



gas under exa- I could perceive any drops of water either in the tube or in 



mutation. (he a p paratus> but I did not obferve the leaft trace of it ; 



neither was the charcoal moifl ; on the contrary, its fur face 



was covered with athes. 



Experiments to be made by faturating the Charcoal frith different 

 Subfiances. 



Experiments ftill 49th. Since, during the progrefs of an investigation, there 

 to be made. are always new experiments which offer themfelves, I per- 

 ceived that it would be inlerefting to make trial w r ith pieces 

 of charcoal faturated with different faline and acid fubitances, 

 as M. M. Rouppe and Van-Norden, of Rotterdam, had un- 

 dertaken to do, and to fee the effects they would produce, 

 with my machine, as well in atmofpheric air as in the differ- 

 ent gafes : But my memoir being of fufficient length already, 

 I leave the care of thefe enquiries to other philofophers ; and 

 this the more willingly, fince it appears that one of the moft 

 able chemifts, M. Van Mons, has engaged in this fubjecl, 

 which, in his hands, will doubtlefs receive every degree of 

 perfection which can be defired. 



50th. I (hall only give the refult of four experiments which 

 I made with atmofpheric air. 



I faturated pieces of charcoal with nitric acid, fulphurie 

 acid, folution of potato, and lime-water j they were not ufed 



until 



