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 

 Avas 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 5| cwt. of coal, which had not previ- 

 ously been converted into coke. Adding to this eight cwt. for heat- 

 ing, and we have 2 tons 13i cwt. 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, thi'ee 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 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 Vv'hat was used in heating the blast : 



Tons. Tons. Tons. 

 In 1829, from 3 furnaces, 111 Iron from 403 Coke, from 8S8 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 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." 



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. 



