Dr. Thomson on Coal Gas. 167 



in my laboratory, which may be about a furlong from the gas- 

 works; now the average quantity in the Greenock gas was 

 10,}, and in the Glasgow 12|. 



The highest specific gravity of the Glasgow gas was 0'582, 

 and the lowest 0'463 ; the average was 0*502. 



The quantity of olefiant gas in Glasgow gas varied from 

 ir77 per cent, to 17*83 per cent; the mean quantity was 

 . 13*52 per cent. 



I got gas made at Greenock with as much care as possible 

 from each of the three varieties of cannel coal found in the 

 neighbourhood of Glasgow, namely Skaterigg, Lesmahagow 

 and Monkland : the specific gravities of these gases were, 

 Skaterigg . . 0*497 

 Lesmahagow 0*560 

 Monkland . . 0*622 

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

 Glasgow . . . 13'52 

 Skaterigg .. 14*15 

 Lesmahagow. 16*66 

 Monkland . . 22*15 

 Mr. Ritchie, the manager of the Greenock gas-works, 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 (juantity of carburetted hydrogen gas in the 

 Glasgow coal-gas was 60*6 percent; the smallest quantity was 

 47*33, and the largest 79*77: the quantity of this gas in the 

 gases from cannel coal was as follows : — 

 Skaterigg . . 66*49 

 Lesmahagow. 59*94 

 Monkland . . 48*77 

 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 dimi- 

 nishes. 



The average quantity of carbonic oxide in Glasgow gas was 

 12 per cent., the smallest quantity was 6*34 per cent., and the 

 greatest quantity 15 per cent.: the quantity of this gas in the 

 three gases from cannel coal was as follows : — 

 Skaterigg . . 7*07 

 Lesmahagow. 12*00 

 Monkland . . 11*76 

 The mean quantity of hydrogen gas in Glasgow gas was 12*44 

 per cent., the greatest quantity was 22*85 per cent., and the 



