Professor Thomas Thomson on Coal Gas. 171 



The olefiant gas, per cent, contained in each was as follows : — 



Mr. Ritchie, the manager of the Greenock gas work, who prepared 

 these gases, told me, that he thought rather too much heat had been 

 applied to the Lesmahagow coal, which, in his opinion, would have 

 somewhat deteriorated the Lesmahagow coal gas. 



The mean quantity of carburetted hydrogen gas in the Glasgow 

 coal gas was 60-6 per cent : the smallest quantity was 47*33, and the 

 largest 7977. The quantity of this gas in the gases from cannel coal 

 were as follows : — 



The goodness of these gases is in the order of naming them. It 

 would appear from this, that the smaller the proportion of carburetted 

 hydrogen the better is the gas. The reason is, that the olefiant gas 

 increases as the carburetted hydrogen diminishes. 



The average quantity of carbonic oxide in Glasgow gas was 12 per 

 cent. : the smallest quantity was 6*34 per cent, and the greatest quan- 

 tity 15 per cent The quantity of this gas in the three gases from 

 cannel coal was as follows : — 



The mean quantity of hydrogen gas in Glasgow gas was 12-44 per 

 cent: the greatest quantity was 22-85 per cent, and the smallest 

 quantity 2*21 per cent. The quantity in the three gases from cannel 

 coal was as follows : — 



The common method of determining the light emitted by gas during 

 its combustion, is to set fire to a jet of a given height, and issuing 

 from an orifice of a given diameter, and to compare it with the light 

 given out by a wax candle of six in the pound, usually denominated 



