Miscellanies. 357 



The Iron furnaces alluded to are worked twenty three hours out 

 of the twenty four ; a half hour every evening, and another every 

 morning, being occupied in letting off the iron produced. During 

 every working hour, the solid materials which feed the furnace at 

 the top, amount to two tons almost exactly, while the air forced in 

 at the bottom, in the same time, amounts to the surprising quantity 

 of six tons. 



Since a smelting furnace must have a very elevated temperature, 

 m order to work it favorably, when we consider the cooling effect of 

 six tons of air an hour — two hundred weight a minute — supplied at 

 the bottom, of the furnace, and entering near the hottest part, it is 

 easy to account for the increased energy of the furnace, when this 

 prodigious refrigeratory is removed, by heating the air before it 

 passes into the furnace. 



We feel, however, bound to add, that Mr. Hartop made to the 

 late scientific Association at Dublin, a communication respecting the 

 use of hot air in iron blast furnaces in Yorkshire, in which he stated, 

 that this mode of supplying the smelting furnaces possessed but few 

 advantages, and also deteriorated the iron, which had, consequently, 

 fallen much in value ; but in the course of a conversation which en- 

 sued, several gentlemen stated, that the price had not so fallen in 

 other parts of the country. 



Long continued effect of heat on mineral substances. — Rev. W. 

 V. Harcourt stated at the Edinburgh meeting in 1835, that the blast 

 furnaces at Low Moor, are sometimes regularly worked for twelve 

 years or more ; but the average is six or seven years. The Else- 

 car furnace, is sometimes blown out at the end of three years. Du- 

 ring these periods, the iron is in constant fusion on the hearths — the 

 bottom stone is always at that temperature, and some portions of the 

 side walls are at a still higher heat, and when the furnace is blown 

 out, the walls cool with extreme slowness. 



The bottom stone, about sixteen inches thick, is worn half through 

 by the action of the melted iron, so that a pool of that metal lies in 

 the hollow ; the cracks are filled with melted metal which occasion- 

 ally penetrates into the sand, on which the stone is laid, and fuses it. 

 It is in metal thus detained within the bottom stone, that the segre- 

 gation of metallic titanium takes place in the iron, or clusters of 

 cubes in accidental vacuities. 



This notice contains a detailed statement of arrangements, very 

 ingeniously made to expose various minerals, and their elements du- 



