SO Dr. Andrew Fyfe on the Comparative Value of 



In the paper already alluded to, I have stated the condensation 

 by chlorine, with the gases prepared from the coals there men- 

 tioned, to vary from 9 to about 20. With two exceptions, I never 

 found it under 12 ; the average of all the trials, amounting to 

 upwards of 20, may be taken as 15, that is, very nearly double 

 of that with the English cannel coal ; and 346 as great as that 

 with the English caking coal; thus making the illuminating 

 power, English caking 1, English cannel 1-85, Scottish cannel 

 3-46. The English cannel being 1, the Scottish cannel is 2, or 



very nearly so. 



The trials with the same gases shew the durability to vary from 

 56' to 94', with the two exceptions above mentioned, it was not 

 below 70' — the average of the trials was 80' ; making the dura- 

 bility as 1-58 to the Newcastle, and 1-48, or 1-45 to the average 



of the English cannel as 1. Now, taking both into account, the 



value of the Scottish parrot-coal gas, bulk for bulk, for affording 

 light in these trials, is as 5*46 to Newcastle as 1, and 2*68 to En- 

 glish parrot as 1. 



Since these experiments were made public, I have been en- 

 gaged in a very extensive series of trials with parrot coals pro- 

 cured from Fifeshire, the Lothians, and the Western districts of 

 Scotland, so as to ascertain the value of the gases which they 

 afford. The gases were manufactured with the experimental 

 apparatus, and under a variety of circumstances, so as not only to 

 secure accuracy, but also to observe how far the manufacture, &c, 

 is affected by a difference in the mode of conducting it. It is not 

 my intention to allude to these farther than to state, that, taking 

 the average of the trials, amounting to upwards of 40, I found 

 the chlorine test, and the durability to be very nearly the same as 

 those given above. 



With regard to the gas with which the towns in Scotland are 

 supplied, I have already said, that in manufacturing it, a mixture 

 of different kinds of coal is employed, according to the situation 

 of the town, and the supply that can be obtained. At Edin- 

 burgh, the coal is chiefly from the Lothians and from Fifeshire. 

 At Glasgow, it is got from Lesmahago, Kelvinside, Wilsontown, 

 &c. At Greenock, Monkland and Skaterig coals are employed. 

 In the towns in the north of Scotland they are obtained chiefly 

 from Lesmahagow and Fifeshire. 



The price of coals varies according to the kind of coal. At 

 Edinburgh and in the west, it is from about 20s. to 23s. per ton. 

 In the north, however, it becomes higher and higher, according 

 to the distance, and, consequently, to the carriage from the pits. 



In the larger towns that I have visited, I have found very little 

 variation in the quality of the gas obtained from the different 

 mixtures used. The chlorine indicated from 13 to 15 ; the aver- 

 age may be taken as 14. The durability was from 70' to 90', 



