Se tae 
ON THE IRON MANUFACTURE IN GREAT BRITAIN. 101 
8 ewt. of coal was consumed. The saving was thus found to be 22 tons of 
coal for each ton of iron. Thus encouraged, further experiments were made. 
The previous heating of the air was raised to 600° Fahrenheit, and it was 
then found, not only that a further great ceconomy was produced in the fuel, 
but that coal could be used for smelting in its raw or uncoked condition. It 
was further discovered that the same blast-machinery, when the air was thus 
heated, sufficed for a greater number of furnaces, so that the power neces- 
sary for three furnaces, when cold air was employed, became ample for four 
furnaces of equal size when the air was previously heated. The result may 
be thus stated :— 
In 1829, using coke and cold air, each ton of iron required for its produc- 
tion 8 tons 1 cwt. 1 qr. of coal. 
In 1830, using coke and heated air, each ton of iron was made with 5 tons 
3 ewt. 1 qr. of coal. 
In 1833, using raw coal and heated air, each ton of iron was made with 
2 tons 5 ewt. 1 qr. of coal. . 
The saving in fuel is thus seen to amount to 72 per cent. 
The effect of the hot-blast upon the quality of the iron produced has 
been the object of many experiments to determine. As those experiments 
were in great part undertaken at the instance of the British Association, and 
as their results have been published from time to time in its Transactions, it 
cannot be necessary to notice them further here. Mr. Neilson’s invention 
was for a long time greatly decried, and to this day it is the practice with 
some few of our leading engineers, when drawing specifications for works, to 
forbid the use of hot-blast iron. Under these circumstances, the introduc- 
tion of this plan has been by no means universal in thé iron-works of England 
and Wales, although it is otherwise in Scotland, where the increased make 
of iron, from 37,500 tons in 1830, to nearly 500,000 tons in the past twelve 
months, may be in great part, if not altogether, ascribed to the ceconomy 
which Mr. Neilson’s plan has occasioned. But for the introduction of that 
plan, we should in all likelihood not have witnessed the unequalled develop- 
ment exhibited during the past fifteen years in this, which has now become 
one of the greatest branches of our national industry. Without this discovery 
our railroad system could not have marched forward with such giant strides, 
and in all probability the application of iron to the building of ships,—an 
application from the extension of which, in future years, so many advantages 
may be made to arise,—might have continued unthought of. 
In a letter which has reached me while writing, from a most intelligent 
iron-master in the North of England *, the subject is thus noticed :— 
“ Previously to this invention, metal was made with such coal only as was 
easily destructible before the blast, thereby admitting a greater quantity of 
air into the furnace. Air is the food of fire. Coals of a stronger or more 
bituminous character were not serviceable; the current of cold air at the 
Tuyeres had the effect of caking the coal and choking the admission of air, 
by which the process of reduction was stopped. But when Mr. Neilson intro- 
duced his method the difficulty was conquered. By heating the air up to 600° 
Fahrenheit, the caking at the Tuyeres no longer took place; the air entered 
freely into the furnace, and coal hitherto unserviceable was enlisted into the 
service of mankind, and applied to the great improvement of their condition. 
“It was pretended that the metal made with hot-blast was not so good; 
that it was weaker; and for a long time it was tabooed in all contracts; but 
this delusion is gradually giving way to truth. There was no foundation for 
such prejudice. It is known that air does not burn until it reaches 3000° 
* Charles Perkins, Esq. 
