112 



REPORT 1844. 



Having thus ascertained the constituents and equivalents in which the 

 combustible and incombustible gases combine, it will easily be determined 

 what quantity of atmospheric air will be necessary to support and effect 

 perfect combustion of the fuel of which the above are constituents. For 

 this purpose it will be observed that a very considerable quantity of air must 

 be brought in contact with the incandescent fuel before the process of com- 

 bustion can be effected, and having already determined the constituents of 

 each, we must next determine the quantity of air required for the purpose of 

 supporting the entire combustion of the gases without producing a diminu- 

 tion of the temperature in the process. 



On this part of the subject several able authorities may be quoted ; but 

 taking that of Professor Brande (as given by Mr. Williams), the following 

 diagram indicates the relative weights of the atoms both before and after 

 combustion : — 



Before 



combustion. 



Weight. 



« a 



8 "" 





U4> 



152 



Elementary 

 mixtures. 

 Atoms. Weight 



I Carbon . . 6 

 1 Hydrogen 1 

 1 Hydrogen 1 



1 Oxygen , 

 1 Oxygen , 

 1 Oxygen , 

 1 Oxygen , 

 ^8 Nitrogen , 



i52 



Products of 

 combustion. 

 Weight. 



12 Carbonic acid. 

 9 Steam. 

 9 Steam. 



112 / Uncombined 

 \ nitrogen. 



152 



Again, for the defiant gas, or bi-carburetted hydrogen, we have — 



Before 

 combustion. 

 Weight. 



14. 



216 S< 



Elementary 

 mixtures. 

 Atoms. Weight 



1 Carbon . . 6_ 

 1 Carbon . . 6 

 1 Hydrogen 

 1 Hydrogen 



1 Oxygen . 



1 Oxygen . 



1 Oxygen . 



1 Oxygen . 



1 Oxygen . 



1 Oxygen . 



12 Nitrogen . 



230 



Products of 

 combustion. 

 Weight. 



_22 Carbonic acid. 

 22 Carbonic acid. 

 9 Steam. 

 9 Steam. 



/ Uncombined 

 nitrogen. 



From the above it must appear obvious that in every instance of combus- 

 tion the nitrogen or azotic gas (which forms so great a proportion of atmo- 

 spheric air) is double the volume and three and a half times the weight of 

 the oxygen, and being in itself incombustible, is absolutely of rio use either 

 as a combustible or supporter of combustion ; on the contrary, it is exceed- 

 ingly injurious, as not combining with the other gases; it reduces the tempe- 

 rature, and thus deprives the fuel of a great portion of its heat, which other? 

 wise would (as in the case of the Bude light) have given much greater in- 





