£]£ ON THE QUANTITY OF CAllBON IN CARBONIC ACID. 



riment, a small receiver R, or the triple socket T S, or any- 

 other combination, may be united. 



V represents the platina tube with its furnace ; the ends 

 of the tube are mounted with female screws of brass, to one 

 Of which the accommodating screw socket AS was joined. 



T is a double section of the platina tray, which contained 

 the substances to be heated. During their combustion, it was 

 made to slide easily within the platina tube P. The accom- 

 modating socket and platina tray are drawn considerably 

 larger in proportion than the instrument. 



By means of the triple socket and the cocks, the gas was 

 made to pass freely over the substances in combustion, from 

 one gasometer to the other ; and by shutting off the commu- 

 nication with the platina tube, while that with the small re- 

 ceiver was open, any portion of gas in the gasometer, fig. 1, 

 might be transferred into eudiometers or measures standing 

 in the mercury bath M, for examination. 



In order to discover whether the several sockets were air- 

 tight, after the apparatus was put together, the communica- 

 tion with the gasometer, fig. 1, was closed, and the other 

 communications opened; the receiver of the gasometer, fig. 

 2, being raised, drew up a column of mercury in the small 

 receiver R, equal to 2 inches: the communication with the 

 gasometer was then closed, and the column was supported 

 ■without alteration. This was always tried previous to, and 

 after every experiment. As the joints would bear this degree 

 of exhaustion, we were confident they would resist a much 

 greater pressure than we had any occasion to employ. The 

 glass tubes G G, which connected the platina tube with the 

 gasometers, enabled us to observe any flash arising from the 

 combustion of hidrogen which might be contained in the 

 substances subjected to experiment. In order to avoid prolix- 

 ity, we shall generally state the method which was invariably 

 followed. 

 Oxigen gas in- We soon found that oxigen gas, even when secured in 

 jured by keep- bottles with ground glass stoppers, was not always to be de- 

 pended upon, but was sensibly deteriorated by keeping; and 

 therefore in all our experiments we made the gas within an 

 hour or two of the time of using it, and always from the hy- 

 Manner in peroxigenised muriate of potash. Its degree of purity was 



constantly 



