Great Exhibition of 1851. 145 



be of much use to it in its present state. But while we find much 

 to admire in the triumphs of practical experience, there is yet great 

 room for the improvement of this art. The cheapness of iron ore, 

 and of the coal used in its smelting, has been so great that, regard- 

 less of their capital importance to this country, we, like careless 

 spendthrifts, use them without thought of the future. 



The mode of smelting iron consists in mixing the ore with lime 

 and coal ; the former producing a slag or glass with the impurities 

 of the ore, while the coal reduces the oxide of iron to its metallic 

 state. Much heat is required in the process of smelting, but the 

 cold air blown in, as the blast, lowers the temperature, and com- 

 pels the addition of fuel, as a compensation for this reduction. 

 Science pointed to this loss, and now the air is heated before being 

 introduced to the furnace. The quantity of coal is wonderfully 

 economized by this application of science ; for instead of seven tons 

 of coal per ton of iron, three tons now suffice, and the amount pro- 

 duced in the same time is nearly sixty per cent. Assuredly this 

 was a great step in advance. Could science do more ? 



Professor Biinsen, in an inquiry in which I was glad to afford 

 him aid, has shewn that she can. We examined the furnaces, in 

 each portion of the burning mass, so as fully to expose the opera- 

 tions in every part of the blazing structure. This seemingly im- 

 possible dissection was accomplished by the simplest means : the 

 furnaces are charged from the top, and the materials gradually de- 

 scend to the bottom ; with the upper charge a long graduated tube 

 was allowed to descend, and the gases streaming from ascertained 

 depths were collected and analysed. Their composition betrayed 

 with perfect accuracy the nature of the actions at each portion of 

 the furnace, and the astonishing fact was elicited, that, in spite of 

 the saving produced by the introduction of the hot blast, no less 

 than 81 J per cent, of fuel is actually lost, only 18 J per cent, being 

 realised. If, in round numbers, we suppose that four- fifths of the fuel 

 be thus wasted, no less than 5,400,000 tons are every year thrown 

 uselessly into the atmosphere ; this being nearly one-seventh of the 

 whole coal annually raised in the United Kingdom. This enor- 

 mous amount of fuel escapes in the form of combustible gases, 

 capable of being collected and economised ; yet in spite of these 

 well-ascertained facts, there are scarcely half-a-dozen furnaces in 

 the United Kingdom where this economy is realised by the utili- 

 zation of the waste gases of the furnace. 



Large quantities of ammonia are annually lost in iron smelting, 

 which might readily be collected. Ammonia is constantly increas- 

 ing in value, and each furnace produces and wastes at least 1 cwt. 

 of its principal salt daily, equivalent to a considerable money loss. 

 With the low price of iron, this subsidiary product is worthy of atten- 

 tion. As I write, a Welsh smelter has visited me, to say that he 

 has adopted this suggestion with advantageous results. I might 



VOL. LIII. NO. CV. — JULY 1852. K 



