Iron . 
141 
consequences approach to extremity, a solution of the 
phenomenon will likely be obtained by the examination 
of the blowing-apparatu s. if air is fitted for combustion 
in proportion as it is free from watery solutions, we are 
not to expect similar results from these blast-furnaces in 
summer, which are blown by air from the regulating cylin- 
der, and those blown by air from a water or air- vault. I 
have for years seen this fact verified, and superior quan- 
tity and quality of iron during the hot weather, obtained 
from a furnace excited by means of blast, from the simple 
regulating cylinder, with a less proportion of fuel than from 
furnaces whose air was expressed by means of the water 
or ah- vault. Observations thus made, where every day 
the effects of the different means could be justly estimated 
and compared, have led me to the following conclusion : 
That the quality of the air, as furnished us by nature in 
our atmosphere, is uniformly more fit for the manufacture 
of crude iron to profitable account, when discharged 
simply by means of cylinders and pistons, than when 
brought into contact with moisture either in the water- 
vault or air- vault. 
So imperfect has the quality of the summer air been 
found in this country for combustion, where the water- 
vault was used, that experiments have been made to re- 
pair the -deficiency of effect by introducing steam into 
the furnace by means of an aperture above the tuyere. 
The inducing motive to this act, was a belief, that com- 
bustion was diminished in consequence of a diminution 
of oxygen gas during the summer ; that, by introducing 
water upon a surface of materials ignited to whiteness, 
decomposition would ensue, a larger quantity of oxygen, 
would then be presented to the fuel, and superior effects, 
as to combustion, obtained in this manner than hitherto 
witnessed. The idea was ingenious, and, in its applica- 
tion to the manufacture of cast iron, original ; but the 
