which are evolved in Coal-Mines. 145 



without doubt caused, at least partly, by the reason already 

 mentioned. 



Among the ternary combinations, only that could occur, con- 

 sisting of hydrogen, carburetted hydrogen, and olefiant gas, if 

 we had 2 m / a. If we for a moment assume this, and, con- 

 trary to all probability, fix any value for m which should be 

 greater than 0.8506, it is easy to see, when we regard the 

 equations for the said ternary combination,* that the amount 

 of the olefiant gas must turn out greater than 0.0198. As 

 now this quantity is much greater than that determined by 

 direct analysis by means of chlorine, such an assumption is 

 altogether deficient in probability. 



Lastly, as to the possible case of the pit-gas of Gerhard's 

 Stotten being a combination of all the four inflammable gases, 

 likewise in that case must 2 m <^ a. Such an assumption 

 would equally leave to be found a larger quantity of olefiant 

 gas, and a smaller quantity of nitrogen, than have been ascer- 

 tained by direct investigations ; and hence this supposition is 

 just as devoid of probability as that of a ternary combination. 



The specific gravity of this pit-gas was determined in the 

 same manner as that of the preceding one. After all correc- 

 tions it is = 0.651275. If we calculate it according to the 

 above analysis, in which we assume the foreign gas to be nitro- 

 gen, it is 0.629560. Although the specific gravity found by ex- 

 periment must at all events turn out somewhat greater than 

 that which is calculated, inasmuch as the gas in the balloon na- 

 turally cannot be entirely free from atmospheric air ; yet the 

 difference is somewhat too considerable to allow us to ascribe it 

 merely to that circumstance. I have indeed examined the gas 

 of the balloon, but unfortunately with a solution of sulphuret of 

 potassium, and I perceived too late that this mode is not appli- 

 cable for the separation of oxygen from inflammable gases.t 

 I was obliged to renounce a repetition of the determination of 

 the specific gravity, because 1 had not enough of the gas. If we 



* These equations are 



J ly drogen = 4 m — 2 a 



Carburetted hydrogen =4a — b — 6 m 



Olefiant gas = 3 m + b — 2a. 



t This pit-gas was the first whose specific gravity I determined. 



VOL. XXX. NO. LIX. JANUARY 1841. K 



