ON CARBURETTED HIDROGE?^ GA«. 323 



eluded it to be a compound of carbon and hidrogen, with- 

 out any sensible quantity of oxigcn. But as neither of 

 these gentlemen has published a detailed account of his 

 experiments, I thought it worth while to examine the gas 

 anew, in order, if possible, to determine the point in a 

 satisfactory manner. I accordingly collected considerable 

 quantities of it at different times in the neighbourhood of 

 Restalrig, where ponds of muddy water are left stagnant, 

 in order to collect manure. This gas 1 found to have the 

 following properties. 



1. It is colourless, and transparent like air. Its propertieg. 



2. It has no smell, and no sensible taste, provided it be 

 previously washed in clean water. 



3. It always contained a mixture of carbonic acid. The 

 least quantity of this gas present was 5 per cent; the 

 greatest 7| per cent. 



4. It always contained a mixture of common air. It is 

 remarkable, that the proportion present was in every c^e 

 the same, and amounted to 12*5 per cent, or 2*5 per cent 

 of oxigen and 10 per cent of azote. Mr. Dalton says, 

 that the gas which he examined contained 20 per cent of 

 azote. This was never the case with the gas from 

 Restalrig; but the common air and carbonic acid gas 

 together sometimes amounted to 20 per cent, and always to ^ 

 Hear that quantity. 



5. After depriving it of its carbonic acid, I found its 

 specific gravity 0-611, that of air being 1-000. But as it 

 contained a mixture of 12-5 per cent of air, it would have 

 been obviously lighter, if this portion had been removed. 

 By calculation I find, that the specific gravity of the pure 

 gas would have been 0-5554*. 



My method of taking the specific gravity of gasses being Method ofta- 

 cxtremely simple, yet precise, I think it worth while ta !^'"^ *^^ ^^^5^' 



. , he gravity ot 



describe it in this place. It is founded on the well-known gasses. 



fact, that, when two gasses are mixed, their bulk does not 



* Let X = the specific gravity of the pure gas, A = the quantity 

 of air in the mixture, a = the specific gravity of air, B= quantity 

 of pure gas present, c = specific gravity of the mixture, we have 

 (A-f B)c-A« 



^ B ' 



Y 2 titer 



