1S6 
Iron . 
the quality of the iron, with the local proportion of fuel, 
will be depreciated 30 per cent . and the quantity reduced 
to 2-3ds or 3-4ths. 
In seeking for a solution of this universally acknow- 
ledged fact, our attention is naturally directed to an exa- 
mination of the various states of air. The quality of the 
air in winter is more fit for combustion than in summer, 
is a truth which requires no farther demonstration. Great- 
er coolness* whereby an almost complete refrigeration of 
moisture takes place, and the presence of perhaps a greater 
relative proportion of oxygen, may account for this phe- 
nomenon. On the contrary, the quality of air during the 
summer months becomes much contaminated for com- 
bustion, by holding in solution a much greater quantity of 
moisture : the abundance of nitrous particles may also di- 
minish the usual proportion of oxygen. 
This will account for the inferior effects of combustion 
both in common fires and in the blast-furnace ; it will also 
in a great measure tend to solve the curious phenomenon 
of pig-iron taking up less carbon in summer, although re- 
duced with a superior quantity of fuel. The air discharg- 
ed most probably contains less oxygen ; yet the metal is 
much less carbonated than at other times, when contrary 
proportions of these exist. Most probably the deficient 
carbon is carried off by dissolving in hydrogen, forming 
a constant stream of hydro-carbonic gas, while the oxy- 
gen that is set free unites to the iron ; and while it reduces 
its quality, at the same time the quantity is reduced by a 
proportion of the metal being lost in the scoria** 
* May not the superabundant azote of the summer atmosphere 
produce part of these effects, by dissolving a portion of the carbon, 
and forming carbonated azotic gas, as has been proved by M. La- 
voisier ? Mushet. 
There is no superabundant azot in a summer atmosphere, nor 
any nitrous particles. T. C< 
