in the Economising of Fuel. 179 



fuel, being inflamed as it proceeds up through the furnace ; and 

 hence the necessity of a greater supply of air than when fuel 

 alone is used. That there I'eally is the combustion of gaseous 

 matter when steam is transmitted, is proved by the change on 

 the appearance of the fuel, for no soouier is the steam admitted 

 than flame is seen to issue profusely from it, and which ceases 

 the moment that vve discontinue its transmission. This experi- 

 ment is well illustrated by using a small furnace, open above, 

 and having the fuel burning briskly, and without flame, in a 

 darkened room. On transmitting the steam from below, the 

 flame will be observed sevei'al inches above the fuel. 



Though there is an increase of heat, and, of course, may be a 

 great saving of time in many processes, by transmitting steam 

 through fuel, another very important point remained to be de- 

 termined, viz. whether this is not gained at an additional expen- 

 diture of fuel in the furnace, and which at first sight, one would 

 naturally suppose would occur, owing to the action of the water 

 on it. 



In conducting this part of the investigation, I have had to 

 contend with difficulties, which almost compelled me to relin- 

 quish the farther investigation of it ; for though, from some ex- 

 periments which were performed, I had every reason for indu- 

 cing me to expect a favourable resiUt, yet, in many, the results 

 were not only not satisfactory, but were really such, as, were 

 there no sources of error, ought to have warranted the conclu- 

 sion that there is an additional consumpt of fuel, and, conse- 

 quently, no saving by the process recommended. 



In the trials which I first made, I found that when the fuel and 

 steam passed through it, it was not more rapidly consumed than 

 when it was burned without it. Thus, in one case, in which 32 

 parts of coke were put into the furnace, and the combustion 

 kept up for an hour and a half, at the expiry of this, 25 j parts 

 ■were consumed; and when the same quantity was used during the 

 same time, along' with steam, there were only 23| consumed. 

 In other trials similar results were obtained ; the quantity of 

 coke consumed, when steam was transmitted through it, some- 

 times being less, at other times very nearly the same. In one 

 instance only it was greater, and, in that case, the additional 

 consumpt amounted to only j'^th of the total consumpt. 



