ACIDIFIABLE COMBUSTIBLES. 



III. There are several gaseous combinations 

 of carbon and hydrogen, which were long con- 

 founded under the general appellation of heavy 

 inflammable airs. Their nature and constitution 

 deserve to be pointed out, because they consti- 

 tute the gaseous substances employed for giving 

 light during the night; and they differ materially 

 from each other in their illuminating powers. 

 They may be divided into two species, which 

 have been distinguished by the names of olefiant 

 gas, and carburetted hydrogen gas. 

 Analysis of i. Olefiant gas was first examined by the 



oletiant . i , i TV/T 



gas. Dutch chemists ; but we are indebted to Mr. 

 Dalton for an accurate knowledge of its com- 

 position. Its specific gravity, as determined by 

 my experiments, is 0-9709 ; but Berzelius and 

 Dulong found it as high as 0-9804*. It will be 

 seen immediately, that my result is about yisth 

 part too low ; while that of Berzelius and Du- 

 long is about Truth part too high. 



It was shown long ago by Mr. Dalton, and the 

 observation was confirmed by my experiments, 

 that one volume of olefiant gas requires for com- 

 plete combustion, three volumes of oxygen gas, 

 and the gas remaining after the combustion 

 amounts to two volumes of carbonic acid gas. 

 The knowledge of this fact will enable us to de- 

 termine the specific gravity, the composition, 

 and the atomic weight of this gas with rigid 

 accuracy. 



