MECHANICS AND USEFUL ARTS. 65 



the Heaton process than good homogeneous steel from the best 

 Cumberhmd pig costs by that of Bessemer. 



]Mr. Bessemer concludes that there can be no competition be- 

 tween his process and Heaton's. 



bessemer's high-pressure furnace. 



Theoretically the total quantity of heat required to raise from 

 an ordinary temperature and fuse a ton of steel does not exceed 

 by more than 30 per cent, that requisite to melt the same weight 

 of cast iron ; but practically, the amount of fuel is 30 times as 

 great in the former as in the latter operation. This waste is due 

 to the fact that the temperature required for the fusion of the 

 metal comes very near the maximum temperature which can be 

 obtained in the furnace, and the heat is communicated to the 

 metal much more slowly than if a greater difference of tempera- 

 ture were available. The production of a very intense heat on a 

 large scale is, practically, very difficult, as it is necessary to guard 

 against radiation and too great access of air, and to secure the 

 complete conversion of carbon into carbonic acid ; the systems of 

 Mr. Siemens and Mr. Schinz, using as fuel carbonic oxide wholly 

 or in part, have remedied the evils in a high degree. Mr. Bes- 

 semer's system may be employed as readily for the combustion of 

 heated air and gases as for solid fuel with a cold blast. Mr. Bes- 

 semer, while meditating the construction of a large lens, 20 feet 

 in diameter, to be mounted equatorially, to collect the rays of the 

 sun from an immense surface for hours together, was led to in- 

 quire why the solar heat was so intense ; and the solution was 

 that the great intensity of the solar heat was due to the fact that 

 the combustion of the solar gases took place under great pres- 

 sure, the force of gravity being at the sun's surface 27.6 times as 

 great as it is at the surface of the earth. He therefore constructed 

 a small cupola furnace, in which the products of combustion could 

 not freely escape, but were maintained under a pressure of 1.5 to 

 18 pounds per square inch above the atmosphere. With this 

 moderate pressure, steel and wrought iron may be melted more 

 readily than cast iron in an ordinary cupola; 3 cwt. of wrought- 

 iron scrap, introduced cold into a small furnace, was run off' com- 

 pletely fluid in 15 minutes. This process, which marks an epoch 

 in the application of heat for metallurgical purposes, is fully de- 

 scribed and illustrated in the London "Engineering," for Sept. 

 17, 1869. . ^ 



the oxyhydrogen light. 



The Oxyhydrogen Light scheme has now taken a definite shape 

 in Paris. A company has been formed, the capital necessary has 

 been raised, and application has been made for permission to lay 

 down pipes to carry ox3'gen and hydrogen over about a fourth of 

 the city. It is not very likely that the permission will be granted, 

 and the promoters will have to confine themselves to supplying 

 individuals with compressed gases, as was originally proposed. 



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