378 Dr Clark 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 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 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- 



