187 Dr Fyfe on the Use of Steam 



were used as in the preceding trials, but a smaller vessel was em- 

 ployed for the evaporation of the water. Furnace in good con- 

 dition, containing coke. Half a pint of water in the pan. 



Without Steam. With Steam. 



In 2\ min. boiled ; iii 8 min. on fur- In 2i boiled; in 8 min. lost 5 oz. 

 nace, lost 4 oz. 



With one pint of water — . 



In 7 min. boiled ; in 15 lost 4i oz. In 5 boiled ; in 15 lost 7 oz. 



In 4 min. boiled; in 12 lost CJ. In SJ boiled; in 12 lost ^\. 



In all of these experiments I found, that, when the steam was 

 used, it required the air to he freely admitted to the inflammable 

 matter. Indeed, when this was not done, instead of there being 

 an increase, there was less heat ; the water in the evaporating 

 pan not being made to boil so quickly when steam was passed 

 through the fuel as when it was omitted. 



Though these experiments prove that there is an increase of 

 heat during the combustion of fuel when steam is passed through 

 it, it became a question whether or not the heat gained is merely 

 that which is carried in by the steam, and which it has acquired 

 from another source. To put this to the test of experiment, it 

 was necessary to compare the quantity of steam transmitted 

 through the fuel with that given off" from the evaporating vessel. 

 In one experiment, in which the ebullition was kept up for ten 

 minutes, the difference in the quantity of water evaporated with 

 steam transmitted and without it, was two and three-fourths of 

 an ounce, whereas the quantity transmitted amounted to only 

 half an ounce, or about one-fifth. In another trial the difference 

 amounted to four times the quantity of steam thrown in, and in 

 others it was occasionally a little more, sometimes a little less, 

 according to the rapidity with which the water was boiled in the 

 boiler. On an average I would say, that, for each ounce of 

 steam thrown into the furnace, there wevefbur ounces additional 

 evaporated over and above that evaporated without the trans- 

 mission of steam, provided the steam was thrown in cautiously, 

 because, when forced in in too great quantity, as before stated, 

 there is no increase, perhaps owing to the whole of it not being 

 decomposed and consumed. 



There can be no doubt, I think, with regard to the cause of 

 the increase of heat in these experiments. It must proceed from 

 the gaseous matter generated by the action of the water on the 



