Different Kinds of Coal for the purpose of Illumination. J9 



The Yorkshire Parrot Coal, in its appearance and quality, is 

 altogether different from the English caking coal. It more nearly 

 resembles the parrot coal of Scotland. The condensation by 

 chlorine was 766 ; the durability, 52' 30" ; pressure at burner, r y 

 A ton of coal yields about 11,500 feet. 



I have already stated, that the chlorine test, with English 



caking-coal gas indicated 4-33, that with the Yorkshire cannel- 



coal gas being 7*66 ; consequently, the illuminating power is as 

 1 to 1-76. The durabilities being 50' 30", and 52' 30", they 

 are as 1 to 1*03; both taken together, makes the value of the 

 latter, for the purpose of illumination, 1*81, to the former, as 

 1(1: 176:: 103: 1-81). 



Wigan Cannel- Coal Gas. — I have had several opportunities 

 of testing the quality of gas from this kind of coal, as at Liver- 



pool, Salford, &c., at which the gas was found to be of the same 



quality. The chlorine indicated 7*55. The durability was 57' ; 

 the pressure at the burner, j^ths and T 9 oths; sp. gr. from 460 to 

 520. The quantity of gas from a ton of coal was 9,500 feet.* 



Newcastle coal-gas being by the chlorine 4-33, and the Wigan 

 cannel gas, 7-55, they are as 1 to 1-73. The durability being 

 50' 30" and 57', they are 1 to 1*12. Taking both into account, 

 then the value is as 1 to 1-93 (1: 1-73:: 112: 1-93), which is 

 nearly the same as that of the gas from Yorkshire cannel, already 

 given as 1-81. We may take the average value of the gas from 

 English parrot coal, so far as these trials go, as 1*85, compared to 

 that from English caking coal, as 1. 



Scottish Parrot Coal — I have had many opportunities of test- 

 ing the quality of gas from this kind of coal, not only as manu- 

 factured at gas-works, but also when made by my experimental 

 apparatus in Edinburgh and Aberdeen. I have already in a paper, 

 published in the Transactions of the Society, for 1842, given the 

 results of numerous trials conducted in Edinburgh. I have now 

 to allude, not only to those made in different towns of Scotland, 

 hut also to a very extended series, more lately carried on with the 

 experimental apparatus. 



The gas, from all the varieties of Scottish parrot coal, is of 

 superior quality to that from the best English parrot : but it va- 

 nes very much according to the kind of coal. In all of the 

 towns in Scotland that I have visited, a mixture of one of fin< 

 quality, and of one or more of inferior quality, is employed in 

 the manufacture of gas ; partly, because the former cannot be got 

 in sufficient quantity; partly, because it is too expensive ; and 

 hence, with one or two exceptions, chiefly in the smaller towns, 

 the quality of the gas was found to be very nearly the same. 



In one instance I found the quantity of gas amount to 11,500 feet; but in this 

 c fse the quality of the xras waa not so good. I prefer, therefore, taking the one 

 above. & 



