THE TECHNOLOGIST. [Feb. 1, 1865. 



328 TIN AND ITS USES. 



called. The quantity of this metal of British produce brought into the 

 market is about 6,000 tons annually. Our annual imports of tin from 

 Singapore, our Indian territories, from China, Peru, and Brazil, amounts 

 to 2,700 tons. Of this foreign tin there is re-exported about 1,100 tons, 

 and of British tin about 4,400 tons annually. 



Much tin ore is contaminated with wolfram, which, as it cannot be 

 removed by the ordinary process of dressing or cleansing, or by the ope- 

 tions of smelting, remains with the metal and renders it of low value. 

 At the Drake Walls Mine they employ a process invented and patented 

 by Mr. Robert Asland. This process is essentially one for effecting the 

 combination of the tungstic acid of the wolfram with soda by roasting 

 and dissolving out the tuiigstate of soda formed, leaving the pure tin 

 behind. Although at present there is no demand for the tungstate of 

 soda, or for the tungstic acid, and it is allowed to run to waste, the 

 increased value of the tin ore thus treated renders the process profitable. 

 Mr. T. A. Phillips has also introduced a process for the purification of 

 tin, which promises many advantages. 



• Attention should be directed to this curious metal — tungsten and its 

 salts — since it appears highly probable that it may be rendered available 

 for some important manufacturing purposes. One of the purposes to 

 which tin is applied is to enable the dyer and calico-printer to give 

 permanence to his reds aud scarlets. For this muriate of tin is largely 

 employed — it was expected that tungsten would have answered this end, 

 and that thus a market might have been created for a new material. 

 Hitherto, however, the experiments have not been successful. Mr. 

 Young has patented a process by which stannate of soda is formed 

 directly from the ore, and this preparation is extensively employed. 



It was formerly considered that tin was one of the superficial for- 

 mations, and that it was useless to seek it at any great depth below the 

 surface. A remarkable example of the incorrectness of this view exists 

 in Dolcoath Mine, near Camborne. This mine was, more than a century 

 since, worked as a tin mine, and was exceedingly productive. As it 

 increased in depth, the mine became poor for tin and exceedingly pro- 

 ductive for copper, and as a copper mine was profitable for a long 

 period. Eventually this mine became so poor that the water was allowed 

 to accumulate in all the lower levels, and those near the surface alone 

 were worked. At length a mining captain advised the removal of all 

 the water from the mine. The recommendation was adopted, and now, 

 at the depth of nearly 300 fathoms — far below the copper — an immense 

 formation of tin is being worked. In 1853 there was produced from 

 this formation 120 tons of tin ore, which was sold for 7,658Z. 5s. 2d. 

 Huel Basset, Huel Buller, South Huel Francis, are, strictly speaking, 

 copper mines, producing, however, large quantities of tin at considerable 

 depths. 



The early history of the Cornish mines, their discovery, and the 

 primitive modes of working them, have occupied the attention and 



