THEOEETICAL AND FOUND VELOCITIES. 



retaining all the heat thereby developed, is proportional to the 

 energy of translation of the same gaseous system, containing 

 only the heat that it retains at zero. 

 4. Here follow the series of tables : 



TABLE I. ONE COMBUSTIBLE GAS ASSOCIATED WITH OXYGEN. 



According to the figures in this table, the theoretical velocity 

 is very near the velocity found by experiment for hydrogen. 



For the hydrocarbons and for cyanogen, this theoretical 

 velocity is rather too high, the discrepancies being comprised 

 between five and twelve hundredths, i.e. the formula keeps 

 within an approximate value. 



For carbonic oxide the discrepancy is much greater, exceed- 

 ing forty hundredths ; thus the formula is not applicable to this 

 . gas (see p. 107). 



It will be seen that it remains approximate, even for gases 

 that are formed with absorption of heat, and that give rise, upon 

 their formation, to the highest temperatures of combustion, such 

 as cyanogen and acetylene. 



It is also approximate for very different ratios of volume 

 between the combustible gases and the oxygen, such as 2 : 5, 6, 

 7, 8, in the series of the hydrocarbons, and 2 : 1 for the 

 hydrogen. 



Lastly, it is approximate for very unequal ratios of condensa- 

 tion in the combination, such as a condensation of a third 

 (hydrogen), of a seventh (acetylene), or the absence of all con- 

 densation (ethylene, methane, cyanogen) ; or even an expansion 

 (ethane). In the calculation of these volumes the water is 



