108 Chronicles of Science. | Jan., 
VIII. MINING AND METALLURGY. 
For some time past the price of Tin ore, or as it is technically 
termed, Black Tin, has been so exceedingly low, that throughout the 
tin-producing districts of the West of England during 1865 not more 
than six mines have been in a position to pay dividends to the 
adventurers. ‘This has arisen from three causes: the failure of the 
American market—the large importation of tin from the Eastern 
Archipelago—and from the British mimes forcing considerable 
quantities of tin upon the market, they being unable otherwise to 
meet the current expenses of the mines. This state of things has 
naturally led to a careful examination of the methods of preparing 
the ores for sale, with a view to the introduction of more economical 
methods. It is not generally known that the process of separating 
tin ore (oxide of tin) from the stone in which it is found is one of 
considerable delicacy. The quantity of tin ore is small compared 
with the valueless matter with which it is mixed. This will be 
evident from the following statement of the quantities of tin ore 
contained in the mass, as it is brought to the surface, from the 
mines named :— 
Huel Kitty, St. Agnes . . . 84 pounds of oxide of tin in every ton. 
Dolcoath, Camborne ae tae! te OO rs sy “3 
Tincrott ditto ae) eiiou + + ” 
North Roskear, ditto otitis, LoD a “A ” 
Huel Uny, Gta es oe pane 2a. © hae » ” 
East Carn Brea, ditto at, Gl eS 3 9 ” 
Polberro Consols, St. Agnes . 14 % ” ” 
Huel Coates, ditto . 6 ” ” ” 
Tanivet; 2°  \. AND Tacs 4 x, ” ” 
The hard quartzose contents of a mineral vein are brought to 
the surface from great depths, and the first operation is to reduce it 
to a state of fine powder, which is suspended in water. This is 
brought about by the continued action of heavy stamps, and the 
mud thus produced is made to pass through the “stamps grate” (a 
perforated plate of copper). This muddy fluid has usually been 
allowed to flow through long narrow troughs—commonly called 
“strips ”"—and when these were filled they were emptied by hand ; 
the upper part of the strip containing the portion which was richest 
in tin, the lower portion being very poor. Dividing the contents of 
this trough and removing it to other machines, either “frames” or 
“puddles,” was a tedious and, consequently, a costly operation. 
Necessity has compelled the miner to reduce this cost as much 
as possible. This has been very successfully done by the use of the 
“round buddle,” which is a circular table, or trough, slightly inclined 
from the centre to the circumference. The thick mud flows in at 
the centre, over the table, and runs off at the edges. By regulating 
the flow of water, and producing a slight degree of agitation by 
