Dr Fyfe on the Evaporative Power of Coal. 271 



was therefore a loss of 26.34 per cent., supposing the whole of 

 the coal thrown into the furnace were consumed. The coal 

 found in the ash-pit was 40.5 lb., thus making the quantity 

 actually consumed amount to 407.5, which would make the 

 evaporation 8.73 for each pound of coal undergoing combus- 

 tion. The evaporative power of this fuel, it has been already 

 stated, as tried by the litharge test, was 10.78. 



Now 10.78 - 8.73 *= 2.05, and 10.78 : 2.05 : : 100 : 19 ; there 

 was therefore a loss of 19 per cent, of the total heat evolved, 

 supposing the 407£ lb. fuel consumed to have undergone 

 complete combustion. With the Scotch coal the loss amount- 

 ed to 28.97 per cent. 



So far as I know, there is only one instance on record of 

 the evaporation produced by anthracite, as tried by actual 

 combustion ; it is that contained in the report lately given in 

 by Dr Schafhaeutl to the Anthracite Company. It was con- 

 ducted with coal of good quality, and with a furnace and 

 boiler fitted up with the patent apparatus of Player, by which, 

 as already stated, the fuel is gradually heated before it is 

 burned, and by which, it is said, the decrepitation is pre- 

 vented, and the combustion is rendered complete and effective. 

 This coal was on analysis found to contain 92.42 per cent, 

 of fixed carbon, 5.97 of volatile matter, and only 1.61 of 

 ashes. Its evaporative power, calculated from its composi- 

 tion, is stated by Schafhaeutl to be 12.3, or the same as pure 

 carbon. When consumed in Player's furnace, it was found 

 that by the combustion of 372.28 lb. there were evaporated 

 3934.3 lb. of water, under a pressure of 13.3 lb., thus giving 

 10.56 lb. for each pound of coal actually consumed, for in this 

 result the cinders were deducted. This is much greater than 

 I obtained, but the smaller amount in my trial is, I conceive, 

 easily accounted for. The coal I used, as tested by litharge, 

 had an evaporative power of 10.78, while that used by Dr 

 Schafhaeutl was 12.3. In my trial the loss of heat was 19 per 

 cent., in the other it was only 14.1. 



(12.3-10.56 = 1.74, and 12.3 : 1.74 : : 100 : 14.1.) 



Though the amount of evaporation in my trial was small, 

 yet there is not much difference according to the calculated 



