SECT . m .] CONDENSATION OF STEAM. 107 



attention to it, is wonderful, considering that it becomes every day more important. 

 It is universally admitted that steam navigation loudly calls for some inquiry. 

 The immense weight of a supply of ordinary fuel renders long voyages almost 

 impracticable ; and while the possibility of making fuel more effective, or of 

 selecting one fuel more effective than another, remains probable, it is worthy of 

 inquiry. 



182. The first and most difficult point is, to determine the heat afforded when 

 two simple or elementary bodies unite and form a compound body ; but when the 

 heat is determined for each of the binary combinations, that afforded by any other 

 combinations of them may be calculated. 



183. The measure of the effect of a combustible is, the number of degrees the 

 heat developed in its combustion will raise the temperature of the same weight of 

 water ; or the weight of water that would be heated one degree, the weight of the 

 substance being unity. 



184. The heat afforded by carbon when it combines with oxygen is variously 

 stated, and the results are in some measure dependent on the method employed for 

 taking the quantity of heat, and in others the difference is owing to the quality of 

 the charcoal. 1 It combines with two-thirds of its weight of oxygen. 



According to Dr. Crawford, 1 Ib. of carbon raises - 10369 Ibs. of water 1 degree. 



Lavoisier ... 13370 >> 



Count Rumford - - 9720 



Clement and Desormes - - 13300 



Hassenfratz - - 12880 



Dalton 5600 



6)65239 

 Mean - 10873 



The greatest discrepancy is in Dalton's experiments, which it appears was owing 

 to the method he employed ; and in taking 10800 Ibs. of water raised one degree 

 as the measure of the effect of carbon, we shall be nearly correct. 



185. The heat afforded by hydrogen when it combines with oxygen is also 



united particle to particle ; and hence I conclude it exists only as a highly compressed gas in solids 

 containing it, for it appears that it does afford the same quantity of heat in all states. 

 1 Phil. Mag. vol. xli. p. 295 ; Thomson's System of Chemistry, vol. i. p. 148. 



