522- EEPOET — 1889. 



■wliicli the fuel was burnt, carbon dioxide was largely the product of its combustion. 

 The oxidising' property of this gas was in eacli the cause of the waste of metal just 

 spoken of. Probably, and for other reasons than avoiding this loss of iron, attempts 

 were made to increase the dimensions of the Stiick-Ofen. If this addition were 

 one of limited extent, the smelter would iind, to his cost, that a substance was 

 obtained which no longer possessed the malleable property of that obtained from 

 the lesser furnace. This change would be due to the absorption of carbon, but not 

 in sufficient quantity to constitute that valuable form of the metal known as cast 

 iron. With a material useless for the smith and incapable from its difficult fusi- 

 bility of being run into moulds, we can understand the delay which took place in 

 the introduction of the blast furnace which about the middle of the sixteenth 

 century gave to cast iron a recognised and valuable position in the arts. 



In those days there was no very exact science to appeal to, for two hundred 

 and fifty years after the ' high furnace ' of the Germans and French had been set 

 to work, Fourcroy in his ' General System of Chemical Knowledge and its Appli- 

 cation to the Phenomena of Science and Art,' arrived at the conclusion that cast 

 metal was erroneously supposed to be a mixture of slag and iron, or a compound of 

 arsenic or manganese and iron. This was written in 1804 in a work of five 

 thousand pages, when be leant to the opinion that Monge and BerthoUet were 

 more correct in considering the product of the blast furnace as consisting of iron, 

 oxygen, and carbon. 



"When the malleable iron-maker had placed in his hands a material containing, 

 as the pig did, more than 90 per cent, of metal, be found it greatly to his advantage 

 to avoid having to deal with all the earthy matter contained in the ores, for it was 

 the presence of silica and alumina which helped to add to the waste incurred in 

 the old hearths. The object sought for in treating ore in the old Catalan fires, 

 as they were called, was one of a reducing or deoxidising character, whereas the 

 reverse of this was required when ore was replaced by pig-iron. In the first case, 

 oxygen had to be removed from the oxide of iron, in the latter oxygen had to be 

 united with the metalloids found in the pig. These were distinctions unknown in 

 the days we are considering, and therefore did not trouble the minds of the iron- 

 masters. In both cases there was a large quantity of oxide of iron present, and 

 when pig-iron was handed over to the Catalan furnace man, it was the oxide of iron 

 so generated which performed the desired duty, and thus tbis simple mode of pro- 

 curing malleable iron remained undisturbed for upwards of two hundred years. 



The discovery which led to the discontinuance of the low blast furnace as a 

 means of procuring iron in its malleable form was that of puddling made by Cort 

 in 1784. In point of fact Cort's process was merely doing in a reverberatory 

 furnace that which was previously effected by means of compressed air. In an 

 economic point of view, however, the difference is great, and its consequences were 

 of immense importance, for to the puddling furnace we were first indebted for an 

 ample supply of cheap iron by which, in a variety of well-known ways, the 

 interests of the human race have been so largely promoted. As an indication of 

 the indifference of those formerly engaged in industrial pursuits to the scientific 

 aspect of their calling, may be mentioned the fact that puddling had been largely 

 followed for upwards of half a century before it occurred to any one to examine 

 the chemistry of the process. 



Down to the beginning of the seventeenth century the only fuel used in the 

 blast furnace, and, indeed, in the manufacture of iron generally, was charcoal. In 

 1620 Dudley made several attempts to substitute mineral coal in his smelting works 

 for vegetable fuel, which, by the exhaustion of timber, had become very expen- 

 sive. He failed in this, and in consequence the British iron trade gradually fell 

 until the entire output was not equal to the production of one modern blast furnace. 

 This happened in 1740, when Darby, by treating pit coal in the same fashion as the 

 charcoal burners had done with wood, i.e., by charring it, restored vitality to an 

 expiring industry. It is true that the restoration must have been of a languid 

 character, for in half a century afterwards it is said the weekly produce of a 

 furnace did not exceed fifteen or sixteen tons. 



Various changes were introduced into the manufacture of iron in the first 



