On the Application of the Hot Blast. 4G5 



viouslv to be converted into coke. Adding to this eight cwt, of 

 coal for heating, we have 2 tons 13 j. cwt. of coal required to make 

 a ton of iron ; whereas, in 1829, when the cold blast was in ope- 

 ration, 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 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 remarkable 

 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. Tons. Tens. 



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 -1 furnaces, '215 Iron from 55-1 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 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 pro- 

 duct 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 be- 

 come necessary to smelt a given quantity of iron." 



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 i: becomes heated. 



4. Dr. Clark gives what we conceive to be the obvious explanation 

 of the mode in which the hot air acts - Berthier, it is true, has broached 

 another.— See "Records," ii. 151.) But it is far-fetched, and su- 

 perseded by the more simple explanation presented by our author. — 

 He observes, mil 



" As nearly as may be, a furnace, as wrought at Clyde Iron- 

 works in 1833, had two tons of solid materials an hour put in at the 

 top, and this supply of two tons an hour was continued for 23 hours 

 a-day, one half-hour every morning, and another every evening, 

 being consumed in letting off the iron made. But the gaseous ma- 

 terial, the hot air— what might be the weight of it ? This can easily 

 be ascertained thus: I find, by comparing the quantities of air con- 

 sumed at Clyde iron-works, and at Calder iron-works, that one fur- 

 nace requires of hot air from 2500 to 3000 cubical feet in a minute. 

 I shall here assume 2807 cubical feet to be the quantity ; a num- 

 ber that I adopt for the sake of simplicity, inasmuch as, calculated 

 vol. in. 2 H 



