28 
oxygen gas than the same volume m summer. As, however, 
the nitrogen gas, &c. from the same cause, must be diminish- 
ed after the same rate, we cannot conceive that the conse- 
quence would be injurious to the blast furnace, provided the 
speed of the blowing engine was accelerated l-7th, so that 
the same quantity of the gases might be thrown in as in the 
winter. On the contrary, we are apprehensive that a benefi- 
cial effect would be experienced, if the air, equally free from 
moisture, could be obtained at 80° temperature : for we pre- 
sume, that oxygen gas unites not with a combustible body at 
a lower temperature than that which produces ignition in that 
body : the heat therefore requisite to add to the presented 
air, that its temperature may be raised to the point of igni- 
tion, must be abstracted from the burning body, and so 
much will the combustion thereof be impeded ; consequently 
the hotter any air is, when equally free from moisture, and 
its proportion of oxygen the same, the greater effect will that 
air produce in a blast furnace. ^ 
We are aware that this proposition will be thought singu- 
lar, and by practical ironmasters treated as chimerical ; for 
we have frequently heard their partiality to a blast that is 
cool, especially in summer. With all due deference to their 
judgment, we must, notwithstanding, suppose their notion to 
originate in error, which we hereafter intend to notice ; and 
in confirmation of our opinion we have the concurrence of 
Mr. Sadler, chemist to the Admiralty, who, perceiving a 
difference in the effects of the blowpipe, which he could 
attribute to nothing but the difference in temperature of the 
air employed, constructed an apparatus, whereby he gave an 
elevated temperature to the air just before its issuing from 
the nozzle ; and by these means he found the heat excited 
so great, as to fuse the purest specimens of native rock 
" crystal, and also those of lime. The other effects were 
" likewise proportionally greater." It is true, oxygen was 
the gas Mr. Sadler made use of, but we see no reason why 
