274 THE SCIENTIFIC PAPERS OF 



the temperature of the blast at 1000, the best results at that time 

 were about 26 cwt., but it struck him that Mr. Samuelson had 

 obtained the calculated minimum result almost completely ; his 

 consumption being 20| cwt., and the temperature of blast about 

 1100. Mr. Bell arrived at nearly the same figures by another 

 mode of reasoning, and had followed up this subject very minutely, 

 by examining into the particular stages of the chemical operation 

 carried on in the blast furnace, deducing very valuable data for 

 the metallurgist. 



Nevertheless, he would not recommend others to follow Mr. 

 Samuelson under all circumstances in the construction of a blast 

 furnace. He was at that moment constructing some blast furnaces 

 of very different dimensions ; they would only have a cubical 

 capacity of 10,000 feet instead of 30,000 feet ; for he believed it 

 would be inexpedient in this case to adopt such extreme dimen- 

 sions. It would require the peculiar conditions of the Cleveland 

 iron district in order to do so with advantage ; namely, an excel- 

 lent hard coke and an ironstone rather strong and comparatively 

 poor. For richer ore and tender coke he believed the size of blast 

 furnace such as Mr. Samuelson had described would be inappli- 

 cable. 



With regard to the effect of extreme capacity, he agreed Avith 

 Mr. Bramwell's views, while at the same time he admitted that 

 Mr. Forbes's remarks were perfectly correct. But Mr. Bramwell 

 spoke of the mechanical absorption of heat the regenerative action 

 within the blast furnace ; on the other hand Mr. Forbes spoke 

 of the chemical action between the gases of the blast furnace and 

 the ores ; and both these actions were subject very much to the 

 same laws. To get from the fuel a maximum of effect in a steam 

 boiler plenty of heating surface was given, as in the case of the 

 Cornish boilers ; and it was reasonable to suppose that more sur- 

 face would give superior results, simply because the difference of 

 temperature between the heat-transmitting current and the heat- 

 receiving surfaces was brought down to a minimum. Where a 

 current of gas flamed rapidly among a mass of solid matter, 

 there must be a considerable difference of temperature between 

 each particle of the fluid and the solid receiving that heat : where- 

 as, if the mass was greater, and the current relatively slower, there 

 must be a more perfect adjustment between the two temperatures, 



