ON THE QUANTITY OV CAR50N IN CARBONIC ACID* 217 



very valuable researches of Smithson Tennant, Esq., on the 

 nature of the diamond, an account of which is printed in 

 the Transactions of tins Society for the year 1797, and which 

 were made previously to the experiments of Guyton ; but 

 notwithstanding this, the result of Guyton's experiment, 

 which only allowed i7*88 per cent of carbon to carbonic 

 acid, has been adopted in all the systems of chemistry to 

 the present time. 



In researches of this nature, the results are much in- 

 fluenced by slight variations* in the quality of the gas; but 

 having- had repeated experience of the accuracy of the eudi- 

 ometer described in No. XII, of this volume*, we were en- 

 abled to proceed in this respect with great confidence. 



Our object was, to consume certain known quantities of Attempt to at. 

 diamond and other carbonaceous substances in oxigen gas, certain the 

 and we at first determined to employ the sun's rays, by means 

 of a powerful lens ; but considering the uncertainty of a 

 favourable opportunity in this country, and at the season in 

 which our experiments were made, we resolved to employ 

 the apparatus respresented by the drawing. 



Description of the apparatus. 



This consisted of two mercurial gasometers, PI. VI, fig. Apparatus de- 

 1 and 2, each capable of containing from 70 to 80 cubic scnbed « 

 inches of gas. The internal cylinder C C is of cast iron, 

 and solid, except the perforation through its middle; the ex- 

 ternal cylinder is also of cast iron ; and the glass receiver 

 slides up and down in the space between them, which is 

 tilled with mercury: not more than 16 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 ex; e- 



* See our last Number, page 86. 



riment, 



