860 
Mr. Taylor on the Smelting of Tin Ores 
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 twenty to seventy feet thick. The tin is in rounded 
fragments, sometimes as large as walnuts, but moie 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 metallic 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 probability originally combined, or to 
enquire whether it is to be attributed to mechanical action, or whether 
it has been effected by decomposition ; but it may be remarked, that 
besides the hematite already mentioned, only the indestructible 
metals, and the oxide of tin, are now discovered existing in deposits 
of this nature. 
The operations of dressing Stream Tin are simpler than those 
for Mine Tin. It is smelted also in a different manner, and 
produces a superior metal known by the name of Grain Tin , which 
is principally used by the dyers, and for the finer purposes. 
The processes for dressing Mine Tin are in many respects the 
same as are used for all other ores, but are subject to some variation, 
which are attributable to the following peculiarities. 
1st. Being for the most part found intimately dispersed throughout 
the matrix, the whole is necessarily pounded down to a very fine 
state to admit of the perfect separation of the ores. 
2d. That being unalterable by moderate degrees of heat, it 
