2S0 Description of an apparatus for the 



This, however, admits of being decided by an accurate com- 

 parison between the weight of the gases consumed and that 

 of the products. 



For the purpose of obtaining a general approximation to 

 the nature of a combustible gas, it may be sufficient to exa- 

 mine its coincidence with those, the properties of which have 

 been already determined. The following table exhibits the 

 results of the combustion of the few gases that appear en- 

 titled to be considered as distinct species. They are deduced 

 from the experiments of Mr. Cruikshank and Mr. Dalton. 



Kind of Gas. 



Sp. Grav. 

 (air =1000.) 



909 



600 



9G7 

 84 



100 measures. 



Take meas. 

 of oxygen. 



Givecarb- 

 acid. 



200 



100 

 90 



Are dimin. 

 by firing. 



200 

 200 



55 



154 



Ok-fiant .... 

 Carbonized hydrogen, frtfni ? 

 stagnant water, $ 

 Carbonic oxide - 

 Hydrogen gas - 



300 



200 



45 

 50 



The inflammability of the compound gases, and their fit- 

 ness for the purpose of affording light, are directly propor- 

 tionate to the quantity of oxygen required for their saturation. 

 The olenant gas, therefore, burns with the greatest brilliancy; 

 carbureted hydrogen gas, though inferior, affords a dense and 

 compact flame ; but the carbonic oxide and hydrogen gas are 

 entirelyunfit to be employed as the mean3 of artificial illumi- 

 nation. 



In the execution of a series of experiments on the com- 

 pound combustible gases, which are described in the Uth 

 volume of Mr. Nicholson's Philosophical Journal, I had rea- 

 son to be dissatisfied with the above method of effecting 

 their decomposition, and to distrust the results which were 

 obtained. The products of the combustion of the same 

 £as varied considerably in different experiments : and, with 

 respect to some, it was evident that the full proportion of 

 their carbonaceous ingredient was not oxygenized, in con- 

 sequence of the precipitation of charcoal in the act of de- 

 tonation. The quantities also, that can be submitted in 

 this wav to experiment, are extremely minute ; and the in- 

 flammation of highly combustible gases is attended, as I 

 l have 



