Fire-damp from the Coal Mines near Newcastle. 9 



plying it to the analysis of atmospheric air it indicated 20*4; 

 per cent, of oxygen. On agitating the air and nitrous gas, 

 just after admitting them into the same tube, the diminution in 

 volume was excessive. In a specimen of nitrogen gas, to 

 which so much air was admitted that the whole mixture con- 

 tained 3 per cent, of oxygen, nitrous gas indicated 3*3 per 

 cent, of oxygen in one experiment, and 3*2 in a second. With 

 nitrogen, which contained 3'6 per cent, of oxygen, nitrous gas 

 indicated 4'-4 in one trial, and in a second 4'1 per cent of oxy- 

 gen. In nitrogen gas, with l-'T per cent, of oxygen, nitrous 

 gas indicated 4*7 per cent, in one trial, and 5"2 in a second. 

 In nitrogen containing 7*3 per cent, of oxygen gas, nitrous 

 gas indicated 7'4' in the first experiment, and S-'t in the second. 

 In the last case a large excess of nitrous gas was employed. 

 In nitrogen gas in one experiment, and ITS in a second*. In 

 this last case also nitrous jjas was used in large excess. 



Mines in whiich the Gas was collected. 



Specific Gravity 

 Observed Calcul. 



5o 



Carb, 



acid. 



Bensham Coal Seam, Wallsend Col 



liery 



Yard Coal Seam, Burraton Colliery- 

 High Main Seam, Killingworth Col- 

 liery 



Low Main Seam, Killingworth Col- 



liery. 



Marquis of Londonderry's Pensher 

 Colliery, from the Hutton Seam 

 Waste, 125 fathoms deep 



Marquis of Lon donderry's Pittington 

 Colliery, Adelaide Pit, Hutton 

 Seam,45 fathoms below the surface 



Eppleton Jane Pit,, Hutton Seam, 

 Hetton Colliery, 175 fathoms be 

 low the surface 



Blossom Pit Main Coal Seam, Het 

 ton Colliery, 100 fathoms below 

 the surface 



Bensham Coal Seam, Jarrow Colliery 



Jarrow Colliery Seam, 11 fathoms 

 below No. y 



Bensham Seam, Willington Colliery, 

 145 fathoms from the surface ... 



0-6024 

 0'600 



0-6196 



0-S226 



0-966 



0-78 

 0-6381 



0-7278 

 1- 



0-5991 

 0-5903 



0-6236 



0-8325 



0-9662 



0-7677 



0-7724 

 0-641 



0-6079 



0-7175 

 1 





 



7 



16-5 



11 



50 

 81-5 



89 



67-5 



23 

 18-5 



28-7 

 100 



In these experiments the error is very uniformly such, that 

 more oxygen was indicated than was actually present. The 

 causes of error appear to be especially twofold, — agitation, 

 and a large excess of nitrous gas. By permitting the action 

 to ensue tranquilly, and avoiding much excess from nitrous 

 gas, the indications in my trials were uniibrni, and very nearly 

 true. Applying the same method to fire-damp, I found that 

 [* Theru appears to be some omission here. Euir. Phil. Mag.] 



