On the Quantity of Carbon in Carhonic Add, Mc. 217 



Description of tlie Apparatus. 



This consisted of two mercurial gasometers, fig. 1 and 2, 

 each capable of containing from 70 to SO cubic inches of gas. 

 The internal cylinder CC is of cast iron, and solid, except 

 the perforation through its middle ; the external cylinder is 

 also of cast iron ; and the glass receiver slides up and down 

 in the space between them, which is filled with mercury : 

 not more than sixteen pounds are required for each, and the 

 small bath B, fig. 1. 



To the top of each receiver, a graduated scale or register 

 H, is screwed, showing the number of cubic inches of gas, 

 measuring from the upper edge of the external iron cylinder. 

 The level of the mercury is ascertained by a small glass 

 gauge. The registers were graduated by throwing up one 

 cubic inch of gas at a time. 



The gasometers stand upon mahogany stools, perforated 

 for a socket, to which, according to the nature of the expe- 

 riment, a small receiver R, or the triple socket TS, or any 

 other combination, may be united. 



P represents the platina tube witli 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 ac- 

 commodating socket and platina tray are drawn considera- 

 bly 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 

 communication with the platina tube, while that with tht 

 small receiver was open, any portion of gas in the gasome- 

 ter, fig. 1. might be transferred into eudiometers or measures 

 standing in thp 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, beingraised, drew up a column of mercury in the small 



receiver 



