378 Dr Cuark on the Application of the Hot Blast 
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 iron 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 re- 
markable effect of Mr Nerison’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 already named, and the successive weekly 
consumpt of fuel put into the furnace, apart from what was used 
in heating the blast : 
Tons. Tons, Tons. 
In 1829, from 3 furnaces, 111 Iron from 403 Coke, from 888 Coal. 
In 1830, from 3 furnaces, 162 Iron from 376 Coke, from 836 Coal. 
In 1833, from 4 furnaces, 245 Iron from 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 
reduced more than double the quantity of iron. The fuel con- 
sumed in these two periods we cannot compare, since, in the 
former, coke was burned, and, in the latter, coal. But on com- 
paring 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 not 
greater than was to be expected, from the diminished fuel that 
had become necessary to smelt a given quantity of iron. 
On the whole, then, the application of the hot blast has caused 
the same fuel to reduce three times as much iron as before, and 
the same blast twice as much as before. 
The proportion of the flux required to reduce a given weight 
of the ore, has also been diminished. The amount of this 
diminution, and other particulars, interesting to practical per- 
