14 Experiments on the Force of Steam. 
force may arise from the increase of density: in this case, 
it would be indifferent as to the expenditure of fuel at 
what temperature steam was used, because the quantity of 
latent heat would be as the force, or as the density : and in 
the distillation of water, the increase of temperature in the 
receiver, arising from the latent heat, would be as the weight 
of water distilled, without regard to the temperature of the 
steam. 
Now, though the preceding experiments do not absolutely 
decide between the first and third supposition, all analogy 
and experience are in favour of the latter. Steam on this 
principle will agree in expansion with all other elastic fluids, 
The experiments of Gay Lussac, as well as my own, on the 
steam of ether, water, &c. are conformable to it; and the 
expansion of vapoury air and dry air by heat are found to 
be exactly the same, provided the vapoury air be com- 
pletely cut off from the acquisition of any more vapour, 
The result of one of the experiments deserves particular 
notice; I mean that in which it was found the temperature 
of the water in the boiler increased in direct proportion to 
the time of heating. One would certainly have expected 
the water to heat most quickly at first, and more slowly as 
the temperature advanced. Ido not doubt the accuracy of 
the experiment; but I explain it by supposing the common 
thermometric scale inaccurate; the degrees of the mercu- 
rial scale are progressively too small as they ascend. See 
my New System of Chemistry, page 14. 
