216 Proceedings of Philosophical Societies. [Sept. 



In dressing mine ore, 'it is necessary to have it very minutely 

 pulverized, in consequence of its being so intimately dispersed 

 through the matrix, a large part of which, from the great specific 

 gravity of the ore, may be removed by washing. It is then 

 smelted in the common reverberatory furnace, mixed with Welsh 

 culm and lime, and exposed to a very strong heat, so as to 

 reduce the whole to a state of perfect fusion. As tin ore 

 consists merely of an oxide mixed with a quantity of extraneous- 

 matter, the only objects to be attended to in smelting are to 

 reduce the earthy matter to a state of perfect fusion, to which 

 the lime contributes, and to remove the oxygen, which is effected 

 by the coal. The produce of the smelting furnace is consider- 

 ably impure, and the metal afterwards goes through the process 

 of refining : this consists essentially in fusing the tin at a low 

 heat, which is not sufficient to melt the other metals with which 

 it is mixed. 



When sufficiently pure, it is cast into moulds, and is sold under 

 the name of block tin. The reduction of grain tin proceeds upon 

 a different principle. After being dressed, it is carried to what 

 is called the blowing house, in which the metal is reduced in a 

 blast furnace by means of charcoal. The blast furnace consists 

 of a cylinder of iron standing on its end, into the upper part of 

 which the ore and charcoal are thrown ; the blast is admitted by 

 a hole near the bottom, and the metal, as it is reduced, flows 

 out at another hole on the opposite side. The metal which is. 

 obtained from these furnaces is further purified by having pieces. 

 of charcoal soaked in water thrown into it while melted ; the 

 water is thus rapidly volatilized, and as it appears, by the agita- 

 tion which it occasions, all the impurities are carried to the 

 surface, where they are easily removed. 



The reading of Mr. Weaver's paper, " On the Geological 

 Relations of the Environs of Tortworth, and the Mendip Range 

 in Somersetshire," was begun. 



KOYAL ACADEMY OF SCIENCES AT PARIS. 



An Analysis of the Labours of the Royal Academy of Sciences 

 daring the Year 1818. 



Mathematical Part.— By M. Le Chevalier Delambre,. 



Perpetual Secretary. 



The Marquis de Laplace has read several important papers 

 to the Academy, containing some extremely curious develop- 

 ments of the theories which he demonstrated in his Mecanique 

 Celeste. The author has given some extracts of them in the 

 Connaissance des Temps ; but these extracts being only intended 

 for mathematicians and astronomers, still contain a multitude of 

 formula? that we cannot admit in this analysis, and for which,, 

 according to custom, we must refer to the papers themselves, as 

 we confine ourselves in this place to exhibit only the clearest 



