256 THE SCIENTIFIC PAPERS OF 



chemical proportions, although there was one of the conclusions 

 arrived at that he could not agree with. 



In reference to the plan of closing in the charging hopper at 

 the furnace top with the additional covering now described, there 

 could be no doubt that a saving of gas must be thereby effected ; 

 and although at first glance it might be thought that the amount 

 of this saving would not be anything material, as the time that 

 the furnace top was open on each occasion of charging seemed 

 only momentary, it appeared from actual observation that this 

 time of opening really amounted altogether to as much as 1-1 6th 

 of the whole time of working of the furnace, representing a loss of 

 l-16th of all the gas evolved from the furnace. At the same time 

 this loss was attended with the additional objection of interruption 

 in the flow of gas to the boiler fires and hot-blast stoves where it 

 was employed for heating purposes ; and it was a decided advan- 

 tage that these interruptions were now entirely obviated by the 

 double closing of the furnace top. 



With regard to the theoretical minimum consumption of 1\ cwt. 

 of coke in the blast furnace for the reduction of 1 ton of iron from 

 the ore, it was certainly true that, with an ironstone containing 

 40 per cent, of iron, 6| cwt. of carbon would suffice to reduce 

 1 ton of iron from the ore by combining with the oxygen con- 

 tained in the ore, and 1 cwt. of carbon in addition would be more 

 than sufficient for the carbonisation of the iron, making the 

 1\ cwt. of carbon per ton of iron ; but he did not see that 

 sufficient heat could then be produced by the combustion of that 

 reduced quantity of carbon in the furnace. Moreover he did not 

 consider that it would be possible in practice to attain to this 

 theoretical minimum consumption of coke by any addition to the 

 height of the blast furnace. A small additional amount of heat 

 might indeed be absorbed from the waste gas by raising the 

 furnaces still higher than at present, but this process could not go 

 on indefinitely, and there would still be a certain surplus of heat 

 that would escape ; because the combustion of coke by atmos- 

 pheric oxygen that was necessary to effect the fusion of a given 

 quantity of reduced ore at a high temperature must always leave a 

 certain margin of heat available for reducing and heating the 

 incoming ore. Moreover as the incoming ore was limited in 

 quantity and possessed only a limited capacity for heat, it followed 



