236 THE SCIENTIFIC PAPERS OF 



pyrometer, which I have constructed for this purpose, but have 

 not yet been able to obtain satisfactory results, owing to the 

 destruction of the coil of platinum wire, which has to be exposed 

 to the heat. My efforts were baffled moreover by the fact, 

 interesting in itself, that platinum wire produced by fusion in 

 Deville's furnace, does not increase in electrical resistance with 

 increase of temperature in the same ratio as that produced by 

 the old process, owing probably to the presence of carbon or other 

 alloy in fractional quantities. 



Avoiding the use of fused platinum wire, I have measured 

 temperatures by electrical resistance up to a full welding heat, 

 which I estimate at 1,600 C. = 2,900 F. ; and in judging 

 the heat of the steel-melting furnace by comparison of effects, 

 I should put it at not less than 2,200 C. = 4,000 F. 

 The effect of this degree of heat may be judged by the 

 following : 



An ingot of rather hard cast-steel, weighing 6 cwt., was intro- 

 duced into the furnace to be incorporated with the bath of steel. 

 The ingot was nearly cold, and was allowed to remain fifteen 

 minutes upon the bank before it was pushed into the bath, where 

 it was completely dissolved in fifteen minutes, the time occupied 

 in heating and melting the ingot being thirty minutes. A cube 

 of wrought metal of nearly 8 inches, weighing 130 Ibs., was also 

 introduced cold into the furnace, and allowed to remain upon 

 the bank during ten minutes to be heated externally to 

 whiteness, before being pushed into the metallic bath, when 

 twelve minutes sufficed to render it completely liquid. It must 

 be borne in mind that these results are produced without a 

 strong draught, the flame being indeed so mild, as not to 

 oxidise the unprotected metal, which can be maintained for 

 several hours as liquid steel in the furnace without adding carbon 

 in any form. 



It may be matter for surprise, that the material composing the 

 furnace can be made to resist such a heat, and it must be admitted 

 that best Dinas brick is the only brick capable of resisting for 

 four to five weeks, by which time the thickness of the arch is 

 reduced to about 2 inches, by the absolute fusion of the inner 

 surface ; but this excessive heat is confined to the heated chamber 

 only, the regenerators being at such a moderate heat, that the 



