280 Chemical Instruments and Operations. 



The measurement may be easily performed by means of the 

 sliding rod eudiometer,* the residue being transferred into, 

 and measured from the receiver, fig. i, same page, agreea- 

 bly to the instructions given in the case of nitric oxide. 



The bihydroguret of carbon, usually called carburetted 

 hydrogen,! consists of two volumes of hydrogen and one of 

 carbon condensed into one volume. This gas not being 

 condensible by chlorine, when light is excluded, a mixture of 

 it with carbonic oxide, should be analysed by the following 

 process. 



^Being mixed with three times its bulk of oxygen gas with- 

 in the bell glass, O N, communicating with the receiver of 

 the sliding rod eudiometer, an adequate quantity may be 

 exploded, pursuant to the directions in the case of carbonic 

 oxide, and olefiant gas. 



More than half a cubic inch of the gaseous mixture, with 

 the necessary addition of oxygen, cannot be safely exploded 

 at once in any ordinary eudiometer ; but by successive ope- 

 rations a large quantity may be exploded, and inferences 

 may be founded upon the accumulated result. 



Let it be imagined that the relative weights of the gaseous 

 mixture in question, of the oxygen gas added to it, and of 

 the carbonic acid produced, have been calculated by multi- 

 plying their respective quantities, as ascertained by the eudi- 

 ometer, by their specific gravities.^ 



Since a mixture of carbonic oxide and bihydroguret of 

 carbon, by combustion with an excess of oxygen, must be 

 wholly converted into water and carbonic acid ; and since 

 the carbonic acid is entirely absorbed by lime water, it follows 

 that the residual gas must be the unconsumed portion of the 

 oxygen gas added to the mixture. Deducting this residual 

 oxygen from the whole quantity of this gas employed, the 

 remainder is the quantity consumed. The weight of the oxy- 

 gen consumed, with the weight of the gaseous mixture, must 

 constitute the whole weight of the products, consisting, ac- 

 cording to the premises, of water and carbonic acid only, 

 and deducting the latter, the remainder will be the whole 



* See this Journal, vol. x. page 76, fig. 6. 



t It is sometimes called light carburetted hydrogen. 



1 The specific gravities of oxygen gas, of carbonic oxide, and of carbonic 

 acid, may be known from the table, page 196, Compendium. That of the gas- 

 eous mixture may be ascertained, agreeably to the instructions in article 184, 

 Compendium. 



