322 IIlDWOGEN A^D CARBOK. 



present. Hence no* pure gasses, fit for examination, and 

 comparable with each other, can be obtained from those 

 vegetable or animal substances which yield an oil when sub- 

 jected to heat, as is the case with most of them. To this 

 oil is to be ascribed the great variation in the specific gra- 

 vity of the gas obtained by distilling pit-coal, as shown by 

 the experiments of Dr. Henry* 

 and carbonic When water and carbon are present together, as is the 



oxidr. jjg^gg ju most animal and vegetable substances, they act on 



each other, and give origin to variable quantities of car- 

 bonic oxide, which must also very much alter the proper- 

 tics of the gas evolved. To these two causes, namely, the 

 oil dissolved, and the carbonic oxide formed, most, if not 

 all the varieties in the combustible gasses, obtained from 

 animal and vegetable substances, are owing. 

 Supposed to Berfhollet, in a dissertation which he lately published, 



s S-^^'" '"^'^^"' in the second volume of the Memoires d'Arcueil, has en- 

 deavoured to proTe, that all the heavy inflammable gasses 

 contain oxigen as a constituent. He has examined a num. 

 ber of gasses obtained by distilling charcoal, and has shown, 

 that each of them contained a considerable proportion, of 

 oxigen. This opinion has likewise been maintain^ by Mr. 

 ^Murray in his System of Chemistry. 



If any confidence can be put in the preceding observa- 

 tions, it is clear, that this obscure subject can never be 

 elucidated by examining gasses from charcoal, or from animal 

 and vegetable substances. The first will always yield car- 

 bonic oxide as well as carburettcd hidrogen, and the gas 

 from the other bodies will be disguised by the oil held by, it 

 in solution. 

 A pure car- Analogy is strongly in favour of the common opinion,^ 



buretted ^'^'^O" that there exists a gas composed simply of hidrogen and 

 «xiss. carbon. Hidrogen, we know, is capable of dissolving 



every other simple combustible, sulphur, phosphorus, and 

 boraciura. Xt dissolves likewise several of the metals, as 

 arsenic, zinc, t^liurium, and potassium. Why then may 

 it not be capable of dissolving carbon ? 

 Gas from stag- There Is a gas which rises in considerable quantity from 

 rant water ex- stagnant watcrs during the summer season. It was exa- 

 mined by Cruickshank and Daitoa^ and both of them con- 

 ,; x<jj/iT. duded 



