S//? WILLIAM SIEMENS, r.R.S. 279 



his views very fully on a former occasion, when the 

 author of the present paper argued on the other side of the 

 question.* He might now state that, in advocating high tempe- 

 rature of blast, he did not look for any great increase of heat in 

 the zone of fusion. He looked for the advantages of hot blast to 

 the greater importation of heat into the whole economy of the 

 blast furnace, resulting, he believed, necessarily, in great saving 

 of fuel. 



In the statements of results which were frequently put forward, 

 certain elements were generally wanting ; and the most important 

 of these was the relative quantity of blast used. If the tempera- 

 ture of the blast was increased without its being stated whether 

 the same quantity was injected relatively to the amount of carbon 

 in the charge, no positive conclusion could be arrived at ; but these 

 discussions would assume a more definite character, if the amount 

 of blast was in all cases stated, and if the working of the furnace 

 was only taken after it had been readjusted after a change of 

 temperature to a minimum percentage of carbon with the charge. 

 It could be easily conceived that with too much carbon the blast 

 would produce an excess of carbonic oxide, and this would issue at 

 the top of the furnace at a very moderate temperature. It might 

 be argued, in that case, that the hot blast produced unfavourable 

 results ; but if an increasing quantity of ore had been mixed with 

 the coke, and the proportion gradually increased with increased 

 temperature of blast till a positive minimum, to insure fusion of 

 the mass, had been reached, the result would have been much more 

 favourable. The general basis which he went upon was, that if 

 free heat was imported into the furnace with the blast, that heat 

 was produced economically in burning fuel into carbonic acid ; 

 whereas the blast furnace could at most produce carbonic oxide, 

 with a proportion of, say, |th or th of carbonic acid. The author 

 had clearly shown that, in producing carbonic oxide, only about 

 * th the amount of heat was produced from a given quantity of 

 coal as when carbonic acid was formed. Therefore every unit of 

 heat applied to the blast outside the furnace represented really 8 

 units of heat produced by the combustion of coke within. 



* Vide The Iroiv and Steel Institute Transactions, Vol. I. i>. 222 ; see p. 264, 

 ante. 



