Fire-damp from the Coal Mines near Newcastle. 7 



to form a plastic mass, which, after receiving the required size 

 and form, was gently dried, and ignited for an instant before 

 the blow-pipe*, and were introduced into the gaseous mixture 

 over mercur)', sometimes cold and at others warm, ten or twenty 

 seconds after incandescence. Their action on all the samples 

 of fire-damp was precisely of the same character with fire- 

 damp, oxygen being previously added or not; the platinum 

 balls, whether cold or warm, were completely inactive. On 

 adding some explosive mixture to the fire-damp, the platinum 

 balls acted readily to their full extent. To give some in- 

 stances. — 



I. With ^re-damp from the yard coal seam, Burratou Col- 

 liery, the specific gravity ofwhich was 0*600. 



With 46*5 measures of this gas, and 12'5 of explosive mix- 

 ture, a platinum ball, nearly cold, caused in ten minutes a loss 

 of volume equal to 12 measures. 



In a second trial the loss in ten minutes was 13"6 in a mix- 

 ture of 49 measures of fire-damp, and 14*'l of explosive mix- 

 ture. 



II. With fire-damp from the Bensham coal seam, Wallseiid 

 Colliery, the specific gravity of which was 0'6024. 



In a mixture made with 34"3 measures of fire-damp, and 

 13*1 of explosive mixture, a platinum ball introduced warm, 

 caused in six minutes a loss of volume equal to 12"4 measures. 



With 43*5 measures of the same gas, and 22*9 of explosive 

 mixture, the loss in eight minutes was 21'7, the platinum ball 

 being introduced warm. 



With 55 measures of the same gas, and 7 of explosive mix- 

 ture, a cold platinum ball caused a loss of 6'3 in six minutes. 



The action was equally rapid with the other gases ; nearly 

 the whole explosive mixture disappearing within the first or se- 

 cond minutes after the introduction of a platinum ball, whether 

 warm or cold. In no instance did barytic water, subsequently 

 admitted, detect in the residue a trace of carbonic acid gas. 



When to any specimen of fire-damp hydrogen was added, 

 the action of platinum always revealed the presence of air. 

 When the quantity of air was small, the action of platinum 

 was ot course slow; nor did it in that case indicate with fide- 

 lity the (juantity of air present, a portion of oxygen not 

 uniting with hydrogen. Thus in the fire-damp from the yard 

 coal seam, Burraton Colliery, nitrous gas indicated the pre- 

 sence of G*2 per cent, of air, and platinum only 3*3 per cent. 

 In the gas from the Bensham Seam, Wallsend Colliery, ni- 



* Before use tlie little bulls were always ignited. 



