in Cornwall and Devonshire . 
S65 
tungsten from the wolfram, which the miners call mock-lead, and 
a portion of undecomposed oxides, sulphurets or arseniats, and of 
some earthy matter or slag. 
The furnace for refining is raised but to a very moderate degree 
of heat, and the plates of tin being placed in it, are suffered to melt 
very gradually, and the metal flows from the furnace at once into 
the kettle, which is now kept hot by a small fire placed beneath it. 
The more infusible substances will now be left in the furnace, and 
a further purification of the tin is obtained by agitating it in the 
kettle for some time, by an operation which they call tossing : this 
is performed by a man with a ladle, who continues for some time 
to take up some of the melted metal, and pour it back into the 
kettle from such a height as to stir up the whole mass and put 
every part into motion. 
When this is discontinued, the surface is carefully skimmed, and 
the impurities thrown up are removed ; these consist of such 
matters as are lighter than the tin, but which are suspended in it, 
and being disengaged by the motion, find their way to the top. 
In general, the metal is at once laded into the moulds, after the 
tossing and skimming is completed, but the produce of impure and 
irony ores may yet require that the tin be divided as much as 
possible from the mixture which may yet remain. This may be 
effected in a great degree by keeping the mass in the kettle in a 
melted state, by which the parts which are heavier than the tin 
will sink to the bottom, and by leaving a proper portion behind, 
the tin will be materially improved. 
The last operation is that of pouring the metal into moulds, 
which are usually formed of granite, and which are of such a size as 
to make it into pieces of somewhat more than three hundred 
weight each. These are called blocks, and are sent according to 
