on some of the leading doctrines of caloric , &c. 393 
but all either frivolous or abortive ; with such prophetic 
judgment had Mr. Watt anticipated the happiest form and 
structure of which it was susceptible. 
Under this conviction, it is with much deference that I draw 
the following practical inferences from the last train of ex- 
periments. 
Since the vapour of alcohol, having the same elastic force 
as the atmosphere, contains of the latent heat of ordinary 
steam, and since its elastic force is doubled at the 206th 
degree ( 6 ° below the boiling heat of water), with perhaps •§- 
of additional caloric ; might we not, in particular circumstances, 
employ this vapour for impelling the piston of a steam 
engine ? The condensing apparatus could, I imagine, be so 
constructed, as to prevent any material loss of the liquid, 
while more than a quadruple power would be obtained from 
the same size of cylinder at 212 0 , with an expenditure of fuel 
not amounting to one half of what aqueous vapour consumes ; 
or the power and fuel would be as 3 to 1, calling their 
relation in ordinary steam 1 to j. A considerable engine 
could thus also be brought within a very moderate compass. 
Possibly, after a few operations of the air pump, the incon- 
densible gas may be so effectually withdrawn, that we might 
be permitted to detach this mechanism, which, though 
essential to common engines, takes away one fourth of their 
power. In a distillery in this country, or on a sugar estate 
in the colonies, a trial of this plan might perhaps be made 
with advantage. While exercising its mechanical functions 
of grinding, mashing or squeezing the canes, it would be 
converting ordinary into strong spirit for rectification, or for 
