

132 



VOLUMES OF ATOMS IN THE GASEOUS STATE. 



The specific gravity or weight of a single volume of hydro- 

 chloric acid is, therefore, obtained by dividing 5078 by 4, and 

 is 1269.5. 



The specific gravity of the vapour of an elementary body, 

 which there are no means of ascertaining experimentally, may 

 sometimes be calculated from the known density of a gaseous 

 compound containing it. The density of carbon vapour may 

 be thus deduced from the observed density of carbonic oxide 

 gas. Assuming that the combining measure of carbon is double 

 that of oxygen, as is true of hydrogen and several other ele- 

 mentary bodies, then carbonic oxide, which like water consists 

 of single equivalents of its constituents, will resemble steam in 

 its constitution also, and be composed of one volume of oxygen 

 gas and two volumes of carbon vapour condensed into two 

 volumes. The weight of a single volume of carbonic oxide 

 being 972. 7, two volumes (1945.4) may be resolved, as shewn 

 in the diagram below, into one volume of oxygen, 1102.6', and 

 two volumes of carbon- vapour, 842.6, (1945.4 1102.6=842.6) 

 each of which it follows must weigh 421.3. 



Combining measure or 

 one volume of oxygen. 



Combining measure or 

 two volumes of carbonic 

 oxide. 



Combining measure or 



two volumes of carbon 



vapour. 



1945.4 



1945.4 



But the density 421.3 thus assigned to carbon vapour will 

 only be true, if it corresponds with hydrogen in its combining 

 measure^ but the combining measure of carbon vapour may 

 as well be one-half that of hydrogen, like that of phos- 

 phorus, or one- sixth like that of sulphur, and then the 

 density will be double or six times that supposed. The 

 important conclusion, however, that the density of carbon 

 vapour is either 421.3, or some multiple or sub-multiple of 

 that number is quite certain. 



The two following tables comprise nearly all the accurate in- 

 formation which chemists at present possess respecting the 

 specific gravities of gaseous bodies. The bodies placed in the 

 first table are generally considered as belonging to the inorganic 

 and those in the second, to the organic department of the 

 science. 



