4o0 Mr, John Taylor on the Smelting of ' ^' [June, 



Mine Tin is, as I have mentioned, the produce of veins, and 

 is raised with a mixture of all the substances which unusually 

 accompany it. There are, not unfrequently, copper ores, pyrites, 

 wolfram, micaceous iron, &c. and the separation of these, as also 

 of the earthy matrix, is the object of various processes of dress- 

 ing, which are conducted with the greatest care, and! require a 

 considerable portion of labour. i; 



Whether, in a country where fuel for smelting is on the whole 

 very cheap, it might not be economical to din^inish the labour 

 of dressing, and, by leaving more to be done in the furnace, 

 reduce the expense of the former operations, is a question that 

 I have never submitted to a direct experiment, though I con- 

 ceive it to be one worthy of trial. The various earths may be 

 quickly separated by fusion, as in the case of copper ores, which 

 are now always smelted with a large mixture of the different kinds 

 of spar in which they are found, all of which is easily run off by 

 the fire, and the scoria or slag separated from the metaUic 

 part. 



The fusibility of tin offers a mode by which it may be separated 

 from an alloy of most other metals with which it is found to exist 

 in veins, as lead and zinc ores are seldom mixed with it. This 

 property is now made use of to a certain extent in refining tin, 

 and might probably be taken advantage of still further, so as to 

 avoid some of the charges incurred in dressing the ore. 



The metal produced from Mine Tin is always of inferior quahty, 

 owing to the mixture of other metals, and which it is probable 

 could not by any mode be entirely got rid of; it is known in 

 commerce by the name of Common or Block Tin, and the quan- 

 tity forms a large proportion of the whole that is brought to 

 market. 



Stream Tin is found in the lowest stratum of alluvial matter, 

 in the bottoms of deep valleys, or places where a considerable 

 deposit of mud, sand, and gravel, has been made by the action 

 of water; it is often discovered occupying a thin bed incumbent 

 on the rock, and covered by an overburden, as the streamers call 

 it, which is sometimes from 20 to 70 feet thick. The tin is in 

 rounded fragments, sometimes as large as walnuts, but more 

 generally in the state of small gravel, and even of fine sand ; it 

 is imbedded in loose matter, composed of the detritus of the. 

 rocks from which it may be supposed to have been separated. 



The principal peculiarity of Stream Tin is the absence of any 

 other metaUic mixtures, except nodules of hematitic iron ore, 

 which sometimes accompany it. This circumstance fits it for 

 producing a very pure metal. This is not the place to speculate 

 on the causes which have so completely freed these ores from 

 substances with which they were in all probabiUty originally 

 combined, or to inquire whether it is to be attributed to mecha- 

 nical action, or whether it has been effected by decomposition ; 

 but it may be remarked that, besides the hematite already men- 



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