inert 
Miscellanies. 181 
iron-works. The temperature of the air under blast, had now 
been raised so as to melt lead, and sometimes zinc, and therefore 
was above 600° Fahr., instead of being 300° as in the year 1830. 
“ During the first six months of the year 1833, when all these 
changes had been fully brought into operation, one ton of cast-iron 
was made by means of 2 tons 54 cwt. of coal, which had not previ- 
ously been converted into coke. Adding to this eight ewt. for heat- 
ing, and we have 2 tons 13: ecwt. of coal required to make a ton of 
iron ; whereas, in 1829, when the cold blast was in operation, 8 tons 
1} cwt. of coal had to be used. This being almost exactly three 
times as much, we have from the change of the cold blast to the hot, 
combined with the use of coal instead of coke, three times as much 
tron made from any given weight of splint coal. 
“During the three successive periods that have been specified, 
the same blowing apparatus was in use; and not the least remarka- 
ble effect of Mr. Neilson’s invention, has been the increased efficacy 
of a given quantity of air in the production of iron. The furnaces 
at Clyde iron-works, which were at first three, have been increased 
to four; and the blast machinery being still the same, the following 
were the successive weekly products of iron during the periods al- 
ready named, and the successive weekly consumpt of fuel put into 
the furnace, apart from what was used in heating the blast : 
Tons. 
In 1829, from 3 furnaces, 111 Iron from 403 Coke, from 888 Coal. 
In 1830, from 3 furnaces, 162 Iron from 376 Coke, pha, 836 Coal. 
In 1833, from 4 furnaces, 245 Iron 554 Coal. 
“‘ Comparing the product of 1829, with the product of 1833, it will 
be observed that the blast, in consequence of being heated, has redu- 
ced more than double the quantitity of iron. The fuel consumed in 
these two periods we cannot compare, since in the former, coke was 
burned, and in the latter coal. But on comparing the consumpt of 
coke in the years 1829 and 1830, we find that although the product 
of iron in the latter period was increased, yet the consumpt of coke 
was rather diminished. Hence the increased efficacy of the blast 
appears to be expected, from the diminished fuel that had become 
necessary to smelt a given quantity of iron.” i 
The temperature was so high, that it was found necessary, in or- 
der to prevent the melting of the cast-iron lining near the nozzles 
of the blowpipes, to substitute for the solid lining a hollow one, filled 
with water, which is continually changing as it becomes heated. 
