390 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



details may be instructive: "Canisters of No. 26 sheet-iron, 

 fifteen inches outside diameter and thirteen inches high, with 

 a tube six inches diameter passing through and through in 

 the centre, including top and bottom, will weigh six pounds. 

 They will hold one hundred and sixteen pounds each of 67 

 per cent, ore, besides the carbon and fluxes. Each canister^ 

 will yield from 75 to 80 per cent, of the metallic iron, includ- 

 ing the six pounds of sheet-iron canister. An estimate for 

 metal transferred in the canisters, while hot, to the open- 

 hearth furnace, sufficient for one ton of steel stock, exclusive 

 of wear and tear and general expenses, foots up to $17.23." 



ANOTHER DIRECT PROCESS, 



The invention of Dr. Siemens, has also been spoken of during 

 the year. The inventor is still engaged in experimenting, 

 with the view of further improvements, and hence no results 

 are available. So far as we can learn, the process consists 

 in melting cast-iron and iron ore together in a furnace, by 

 which the carbon of the former combines with the oxygen 

 of the latter, and leaves the resulting mass free from carbon. 

 From time to time samples of the metal are drawn from the 

 furnace and the progress of the transformation observed. 

 When all the carbon has disappeared, a requisite quantity 

 of spiegel-eisen is added, and the mass thereby converted, 

 as in the Bessemer process, into steel. 



COMPARISON OF A COAL-FURNACE AND A SIEMENS GAS- 

 FURNACE IN THE MANUFACTURE OF PLATE-GLASS. 



The following comparative statement, furnished by one of 

 our leading Western establishments, affords a striking evi- 

 dence of the superiority of the gas-furnace in this special 

 industry: 



The coal- furnace contained twelve pots, each having a 

 capacity of 800 pounds giving, therefore, 9600 pounds to a 

 melt, averaging twelve hours to a heat, and consuming 

 twelve tons of coal per twenty-four hours. The flame in- 

 tensity was unequal, and in consequence of this non-uniform- 

 ity of heating, the breakage of pots was considerable. The 

 quality of glass made was variable; and from the impure 

 character of the flame, the pots needed considerable skim- 

 ming. 



