Feb. 1, 1865.] THE TECHNOLOGIST. 



TIN AND ITS USES. 333 



sighing over the heated and quiescent mass, the smelter discharges the 

 contents into a receiver built of fire-bricks and clay. When the highly- 

 heated mass has cooled, a scoria which coats it is removed, and it is 

 formed into small blocks of one cwt. each. When a number of these 

 blocks are obtained, the second process of refining or purifying is com- 

 menced, — 1st. The furnace is brought to a gentle heat that will just 

 melt the tin, a few degrees only above boiling water, in this condition 

 it receives these small blocks, which are skilfully placed in it, and the 

 more fluid portion runs off. This is received into an iron vessel, having 

 a fire beneath it, and when full the furnace is again heated up, and the 

 dross and heavier and impure portions that are left behind are roasted, 

 and then formed into small blocks to be merged in the next operation. 

 2nd. The tin contained in the iron vessel is subjected to a further pro- 

 cess. A piece of thoroughly-saturated balk timber is forcibly kept at 

 the bottom of the vessel which produces great disturbance of the metal, 

 and causes dross to rise to the surface, thus relieving it of a further 

 portion of impurity, which is discoverable by the assay showing a 

 cleaner surface and greater ductility. This operation is called " boiling " 

 the tin. 3rd. The last process, called " tossing" the tin, now takes 

 place. This is accomplished by means of large ladles having handles, 

 about twelve feet in length, which rest upon a fulcrum ; and the tin is 

 tossed high into the air, and allowed to fall again into the liquid mass, 

 which causes a further discharge of its impurities. During all these 

 operations the tin has gradually assumed a condition which may be 

 understood by the word " fineness :" it has become more fluid, more 

 crystalline, the dross much finer, resembling charred wood. It is now 

 manifest that it has been cleared of the extraneous substances which 

 deteriorated its condition, and that a sub-oxide of tin is forming. It is 

 now refined to the required standard, and put into moulds of various 

 sizes to meet the conveniences of the consumer. 



It has been observed that culm has been used in the operation of 

 smelting, for the obvious reason that it contains carbonic gas, which 

 unites with the oxygen from the mineral : this necessary article after 

 use is called " slag," and is pounded by stamps, and subjected to various 

 processes of washing, by which means the small particles of tin are 

 collected, with which it is permeated, and are merged into the mass of 

 new smeltings. 



Such is an outline of the mode of smelting tin, which has been 

 maintained, with little variation, for many years past ; to trace its in- 

 dividual history, and its history in conjunction with other metals, would 

 alone be a subject of considerable interest. While discoveries are con- 

 stantly adding to the wealth of the repertoire of metallurgy, but little 

 has been done as regards tin. In comparison to the importance of other 

 metallurgical operations, it may be insignificant ; but yet a metal with 

 an annual yield of 7,000 tons cannot be unworthy of the philosopher's 

 attention ; and it may not be too much to suspect that, sooner or later, 



