WILLIAM SIEMENS, F.R.S. 275 



giving rise to a more economical result. In the same way the 

 chniiical action would be more perfect if a gas containing a cer- 

 tain proportion of carbonic oxide (mixed with carbonic acid and 

 nitrogen) had plenty of time to communicate its carbon to the 

 pitrc of ore which was ready to take it in yielding up its oxygen. 

 If the quantity of material present were infinite a perfect adjust- 

 ment between these conditions would arise, depending upon the 

 temperature and the proportional amount of carbonic oxide pre- 

 sent ; but such a condition of equilibrium could never be obtained. 

 It was therefore necessary in practice to consider how much 

 would suffice for the purpose, because other considerations entered 

 into the subject. If a blast furnace was very large in proportion 

 to the quantity of work that was to be performed in it, a greater 

 economy would be attained by a relative increase of first cost. 

 This was the case in Mr. Samuelson's blast furnaces, where 30,000 

 cubic feet capacity produced only 500 tons of pig metal per week ; 

 whereas a furnace with a capacity of 10,000 or 11,000 cubic feet 

 would produce 300 tons. It was therefore clear that these large 

 furnaces produced approximately only about one-half the amount 

 of work per cubic foot of capacity that the smaller furnace did. 

 The question arose how far was it judicious to expend more 

 capital to obtain additional saving, if other means might be 

 resorted to of arriving at the same, or even a greater increase of 

 economy. This point had not been touched upon in the course of 

 the discussion. Mr. Bramwell had shown that where there was a 

 greater outgoing current than a heat-absorbing material to meet 

 it, an unstable condition or waste of heat must ensue ; and Mr. 

 Forbes has argued in the same way on chemical grounds. In the 

 blast furnace the object was to waste as little heat as possible, and 

 to bring out the gases at the top as cool and as thoroughly de- 

 prived of their chemical or reducing power as was practicable. 

 Both these objects were obtained by diminishing the relative 

 quantity of gases. If, for instance, the relative amount of gases 

 for a given amount of incoming material could be reduced by 

 one-half, and if the chemical conditions were the same, it was 

 clear that the smaller quantity would be more thoroughly deprived 

 of its heat ; but the smaller quantity would have had time to 

 divest itself more thoroughly of its chemical action also : there 

 would be a larger relative amount of carbonic acid gas produced, 



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