GASES ABSORBED BY CHARCOAL. 19 



until they had been thoroughly dried on filtering-paper. I 

 put them cold into my machine. The following are the 

 refults : 



lft. In the firft fix hours the charcoal, faturated with nitric EfFe£sof char, 

 acid, produced an abforption of four lines and a half; alter- witll nitric acid . 

 wards it gave back the air, and even deprefled the mercury 

 below its level. 



2d. The charcoal, faturated with fulphuric acid, effecled withfulphurie 

 an abforption of nine lines, which it preferved uniformly for 

 twenty-four hours. 



3d. The charcoal, faturated with folution of potafli, made wUh 'folutiou of 

 an abforption of three lines, and remained fo for twenty-four ' 



hours. 



4th. That, faturated with lime-water, made only a fmall with lime-water, 

 abforption of a line and a half, although it was kept in expe- 

 riment for twenty-four hours. 



Thefe four experiments prove that charcoal, faturated with Charcoal lofes Iti 

 different fubftances, lofes, in part, its power of abforbing : by b e ; ng f a tu- 

 probably thefe folutions, by filling the pores of the charcoal, rated ^'^h fome 

 in fome meafure deprive it of this property. fubftances. 



51ft. No perfon can be more aware than I am, that my 

 enquiry is far from being carried to that degree of perfection 

 which I wifhed : I hope, neverthelefs, that philofophers will 

 not be difiatisfied that I have prefented them with new expe- 

 riments, and have made them acquainted with an inftrument, 

 by means of which they can appreciate the effe&s of folar light 

 and caloric on charcoal ; an inftrument which, in many cafes, 

 will ferve them for an eudiometer, and which, when azote 

 fhall be better known, will acquire greater precifion. I hope 

 that, by the labours of other philofophers who may employ 

 themfelves on this fubje£t, this interefting branch of natural 

 philofophy will be brought to perfection, and an explanation 

 of thefe furprifing phenomena be obtained. 



C 2 Farther 



