180 Dr Fyfe o« the Use of Steam 



In these trials, the proportion of fuel consumed was in the 

 ratio of 



With Steam. Without it. Excess. 



840 970 130 



4840 5190 S , 350 



1330 1370 40 



1330 1570 240 



Now, connecting this fact with the results of experiments on 

 the quantity of water evaporated, in a given time, which, it has 

 been shewn, is always greater when steam is used than when 

 omitted, there was every reason for believing, that there was 

 really something gained by the use of steam ; but when I next 

 attempted to compare the actual quantity of water evaporated, 

 with the fuel used, I found in my first trials, that sometimes it 

 was not greater, indeed, in many trials, it was less. This na- 

 turally led me to suspect some source of error ; accordingly, in 

 repeating the experiments over and over again, varying them 

 in every way I could think of, I at last found, that, towards 

 the end of the process, that is, when the fuel was nearly ex- 

 hausted, and consequently the temperature was comparatively 

 low, the steam seemed to escape decomposition. I was induced, 

 therefore, to perform the experiments in a different way, and 

 the results were then as I expected. The method followed, 

 was to keep up the action, with and without steam, for a 

 shorter period than I had done before, taking care to have the 

 furnace all the time in good condition, instead of allowing 

 nearly the whole of the fuel to be used, and of course having 

 the heat at some time too low. In this method of conducting 

 the process, I found, with very few exceptions, that there was 

 rather less fuel consumed, when steam was transmitted through 

 It than when omitted, while, at the same time, the quantity of 

 Avater evaporated was increased. 



It has been suggested to me that the increase of heat, by 

 causing steam to pass through fuel, may be owing, in a great 

 measure, to its acting merely as a blast, by carrying in a large 

 supply of air along with it. That this is not the case, is 

 proved, I think, by experiments which I have since performed, 

 by introducing the steam in different ways, more particularly by 

 luting the steam-pipe to the side of the furnace, to prevent 

 the access of air along with it; in all of which cases, there was 

 also an increase of heat. Besides, I have always fouiid, that 



