Dr Fyfe on the Prevention of Smoke, ^c. 55 



proper construction of the furnace, and by the due admission 

 of air, so as to prevent the escape of any part of the volatile 

 inflammable matter unconsumed, the evaporative power of 

 bituminous coal, when burned by these means, does not go 

 beyond that which the fixed carbon of the coal will afford, an 

 important question flows from what has been stated as the re- 

 sults from the foregoing calculations. Can the evaporative 

 power be increased beyond that of the fixed carbon ; in other 

 words can the gaseous products be also so consumed, that the 

 heat evolved by their combustion, will also cause the evapo- 

 ration of water, and thus increase the total amount of evapo- 

 ration ? The process which I am now to describe is one by 

 which that object can be obtained. It is a modification of that 

 to which I formerly drew the attention of the Society, and an 

 account of which is published in the Transactions for 1838. I 

 then shewed that by propelling steam up through the fuel,, when 

 in a state of combustion, the evaporative power is increased. 

 I intend now to illustrate another remarkable circumstanoo 

 accompanying the use of steam. When, instead of being 

 introduced from below so as to make it pass up through 

 the fuel, it is projected above it, a similar result is obtained 

 as to increase in evaporative power, and, in addition to this, 

 there is also the very desirable object, the total prevention of 

 smoke. This constitutes the process lately patented by Mr 

 Ivison of the Castle Silk-Mills of this place. From the nume- 

 rous opportunities I have had of conducting experiments with 

 it, and, from the very interesting results which I have ob- 

 tained, I have thought it advisable to lay an account of them 

 before the Society. From the time occupied in carrying them 

 on, they are, I conceive, valuable as giving results from trials 

 on a large scale ; and from the minute attention bestowed 

 on them, I may be permitted to state, that the most implicit 

 confidence may be placed in them. Though I have wit- 

 nessed many trials, yet my remarks will be confined exclu* 

 sively to those conducted under my own superintendence, 

 having been present during the whole of the time, and having 

 myself assisted at the weighing of the fuel, and in measuring 

 the supply of water to the boiler, so as to secure accuracy in 

 the results. 



