Ttn. 
3 55 
ed this to be a sulphuret of tin : it is very compact, of a 
blueish white colour, approaching to gray steel, and simi- 
lar to the colour of gray copper ore : it is lamellar in its. 
texture, and veiy brittle. It consists of sulphur, tin, cop- 
per and some iron. Raspe proposes to call it bell- metal 
ore. 
According to Klaproth’s analysis of this ore, 100 parts 
contain 25 of pure sulphur, 34 of tin, 36 of copper, 2 of 
iron, and three grains of the stony matrix. A faint smell 
of arsenic was perceptible in roasting it. The darker va- 
rieties, however, are much poorer in tin, and contain more 
iron. 
Bergman’s method of assaying tin ores in the humid 
way is too commonly ineffectual. Klaproth gives the 
following mode. Mix the ore, in fine powder, with a 
lixivium containing six times its weight of caustic pot- 
ash ; evaporate to dryness, in a silver vessel, on a sand 
heat ; and then keep in a state of moderate ignition for 
half an hour. Dilute the mass, while yet warm, with 
boiling water, and filter. Let the residuum be again ig« 
mted with six times its Weight of potash, and dissolve in 
boiling water, as before. Mix the solutions, and add mu- 
riatic acid, till the precipitate, which falls down, is dis- 
solved by its excess. Separate the tin from the acid by 
carbonat of soda ; wash the precipitate ; dry it ; and re- 
dissolve it in muriatic acid by a gentle heat. Into the 
colourless solution, diluted with two or three parts of wa- 
ter, put a stick of zinc, and in a few days the whole of 
the tin will gather round it in dendritic laminae. The re- 
siduum left after the second solution is to be treated with 
muriatic acid, and what tin is in it precipitated by zinc in 
the same manner. If it contain any iron, this may now be 
precipitated by prussiat of potash. 
The sulphuret requires to be treated somewhat differ- 
ently. To one part of the powdered ore add four of mu- 
Vol. III. ‘ Xx 
