960 



IRON 



from which must be deducted the coal used in heating the air, which was nearly 8 cwts. 

 This great success induced the Scotch ironmasters to try a higher temperature, and 

 to substitute raw coal for coke ; and during the first six months of the year 1833, the 



1232 



blast being heated to 600, 1 ton of cast iron was made with 2 tons 5^ cwts. of coal. 

 Add to this 8 cwts. of coal for heating, and we have 2 tons 13 cwts. of coal to mako 

 1 ton of iron. An extraordinary impetus was given by this discovery to the iron 

 manufacture of Scotland, where, from the peculiar nature of the coal, and from the 

 circumstance that, with a heated blast, Mushet's blackband ironstone could be exclu- 

 sively used, its importance was more highly felt than in England and Wales. Ac- 

 cording to Mr. Finch's statement (Scrivcnor's 'History of the Iron Trade'), tlu-r.i 

 were in 1830 only eight works in operation in Scotland, which made in that year 

 37,500 tons of pig-iron; in 1838 there were eleven works, consisting of 41 furnaces, 

 which made 147,500 tons, being an increase in eight years of 110,000 tons per 

 annum; in 1859 there were fifty furnaces in blast, making 195,000 tons ; in 1851, 

 750,000 tons of pig-iron were made ; and in 1856, with 127 furnaces in blast, the 

 make rose to 880,500 tons. The influence of hot blast has likewise been felt in tho 

 anthracite districts of South Wales, where that coal is now successfully used, and 

 where several new furnaces have in consequence been erected. In short, notwith- 

 standing the opposition with which the introduction of hot blast was met by engineers, 

 as being destructive of the quality of the iron, so great have been tho advantages 

 derived from it that at tho present time moro than nim -teen-twentieths of the entiro 

 produce of the kingdom is made in furnaces blown with heated air. 



Of late years there has been a constantly increasing <!em;uul, especially in tho 

 Cleveland district, for more highly heated blast; and furnaces are now blown with 

 nir at a red heat, or almost beyond the power of endurance of cast-iron heating pipes. 

 For this purpose the regenerative principle of Siemens has been advantageously 



