Fire-damp from the Coal Mines near Newcaslle. 5 



trials with nitrous gas, it was found to contain 3*7 per cent, 

 of oxygen, equivalent to 18'5 of air. A gaseous mixture of 

 18-5 air, and 8 1*5 real marsh gas, should have a specific 

 gravity of O-Gil, since 0-5595 + 0-815 + 0-185= Oeil. 



Of this gas 13-5 measures, inferred from the foregoing 

 premises to contain 0-5 of oxygen and 11 of real marsh gas, 

 were fired with 30 measures of oxygen, which contained 28'8 

 of real oxygen gas. 



Loss of volume due to production of water = 22*8 



Carbonic acid gas generated = 11-2 



Residual oxygen = 6-4 



Deducting 17'6 from 29-3 there remain, as 

 Oxygen gas which went to the produc- 

 tion of water = 11*7 



III. Analysis of a gas from ike Eppleton Jane Pit, Hutton 

 Seam, Melton Collier]/, collected at a depth of \1 5 fathoms 

 belo'w the surface. 

 Specific gravity actually observed = 0-78. 



This gas was quite free from carbonic acid. Two experi- 

 ments with nitrous gas agreed in indicating the presence of 

 4-6 per cent, of oxygen, equivalent to 23 measures of air. 

 Analysis indicated the presence of 50 per cent, of real marsh 

 gas, leaving 27 per cent, as nitrogen, independently of that 

 already considered as atmospheric air. 



Of this gas 1 1 measures, containing 0-5 of oxygen, wei'e 

 fired with 28 of oxygen gas, which contained 26-9 of real 

 oxygen. 



Loss of volume due to formation of water... = 10-5 



Carbonic acid gas generated = 5'5 



Re.eidual oxygen = 16-4 



Deducting 5-5+16-4 = 21-9 from 27-4 there 

 remain, as Oxygen gas which went to the 



formation of water = 5'B 



A gaseous mixture, consisting of 50 measures of real marsh 

 gas, 23 of air, and 27 of nitrogen, should have a specific 

 gravity of 0-7724, since 0-5595 +0-5 +0*23 + 0-9727+ 0-27 

 = 0-7724. 



The first of the foregoing analyses supplies an instance 

 where the loss of carbon was decisive. In the second and 

 third, as in the whole series of successful analyses, the car- 

 bonic acid gas may be taken as exactly ecjual to hall' the con- 

 densation due to the formation of water, and as containing 

 half the oxygen which was required for complete combustion. 

 The quantity of marsh gas present was equal to half the oxy- 

 gen rc"(|uired tor its complete combustion, lo half the con- 

 densation due to irenerated water, and to the volume of car- 



