SULPHURIC ACID FOR WATER. 393 
Vol. 1, second series: and, from the very active 
manner in which combination of the gases is 
known to take place when plenty of aqueous 
vapour is present, I cannot conceive that any 
additional impulse is required. Dr. Ure admits 
that the chemical agency of steam is more im- 
portant than its mechanical agency ; and, in this 
I fully agree with him: but, of course, for the 
reason given in my foregoing paper, I do not 
concur with him in thinking it advisable that the 
steam should be furnished by a jet from a boiler, 
but that it is preferable for it to be derived from 
the liquid on the floors of the chambers. Not 
admitting the necessity of its mechanical agency, 
high pressure steam is essentially no more bene- 
ficial than low pressure steam ; because, from the 
conversion of it to the liquid state, it is not capa- 
ble of communicating to the interior of the cham- 
bers any higher a temperature than low pressure 
steam, since the same weight of steam, whether 
under high or low pressure, contains exactly the 
same quantity of caloric. 
H. H. WATSON. 
Bolton, April Ist, 1839. 
