60 f. b. guthrie and a. a. atkinson. 



Gases at Gob Fire at Greta Colliery. 

 Spontaneous fires have occurred at this colliery, and some years 

 ago it was found necessary to seal off the old workings by means 

 of stoppings. The gas examined was collected from one of these 

 stoppings (a brick one) by means of an iron pipe with a tap. 

 Temperature of air issuing from pipe 75 degrees F. Temperature 

 of outside air 72 degrees F. 



Composition of samples. 



Carbon dioxide. Oxygen. Nitrogen. 

 (A.) 2-14 10-50 87-36 



(B.) 2-17 10-60 87-23 



The gas instantly extinguished flame. It is noteworthy that 

 these samples did not contain any carbon monoxide. 



It appears interesting to discuss the question whether the 

 samples of air obtained from Greta and Gunnedah as the result 

 of fire contained any appreciable quantity of black damp, which 

 latter, according to Dr. Haldane is the residual gas left on oxida- 

 tion of coal by the air, 1 and is of fairly constant composition, 

 containing about 13 per cent. C0 2 and 87 per cent, nitrogen. 



In the case of the Greta gas, the residual after deducting the 

 unaltered air contains 4*4 per cent. C0 2 and 95-6 per cent, 

 nitrogen in the sample (B.), and 4-3 per cent. C0 2 and 95*7 per 

 cent, nitrogen in the sample (A.), Neither of these approach the 

 composition of black damp, but this may be due to diffusion or to 

 incomplete oxidation. 



Neither the Gunnehah nor Greta Collieries give off much fire- 

 damp, but the following samples show the composition of gases 

 obtained from the Dudley Colliery, Newcastle, N. S. Wales, and 

 Harecastle, England, both of which make firedamp, after being 

 closed down in consequence of explosion and fires underground. 



1 Trans. Fed. Inst., Vol. vin., p. 553. 



