172
Class 1.—MINING AND MINERAL PRODUCTS.South Side—Areas S. 1 to S. 27.
[United
mines in a year, if laid in one continuous line, "wouldextend upwards of 70 miles in length.
No. 40. A cake of silver produced from lead raised inMr. Beaumont’s mines, and weighing 8,000 ounces.
485 Oxland, Robert, Buchland Street , Plymouth —Inventor and Manufacturer.
A series of specimens illustrative of an improved processfor dressing ores of tin ; containing wolfram (the tung-state of iron and manganese). Invented by the exhibitor,for the separation of the wolfram from the ores of theDrake Walls Tin Mine, on the Cornish side of the riverTamar. This process is now in regular operation atthe mine. In consequence of the specific gravity ofwolfram, which is from 7*100 to 7'■’500, being greaterthanthat of the black tin of the mines or the pure nativeoxide of tin, which is only from 6’3 to 7*00, it has beenfound impossible to separate the wolfram from the tinoxide by the usual mechanical process of washing in astream of water. This led to the necessity of adoptingthe patent chemical process explained with the descriptionof the series of specimens.
No. 1. “ Tin witts:” the ore obtained from the stamp*-floors, where, subsequently to its having been crushed orstamped down to a suitable size, it has been washed in astream of water, in order to separate the earthy particleswith which it was associated. The clean “witts” containnative oxide of tin; black tin, or rosin-tin and wolfram,with iron and arsenical pyrites, generally containing somecopper. In the course of washing, the “ witts ” are sortedinto differenl parcels, according to the size of the particles,and are known as jigged, marked A ; flucan, B; smalls,or “ smales,” C ; slime, D; roughs, or rows, E. The“witts” are calcined in a reverberatory furnace, usuallyconstructed of fire-brick throughout; but the furnace,of which a drawing is exhibited, has been found to beas well adapted for this purpose, as for the process forwhich it was originally intended. The calcination is con-tinued until all the sulphur and arsenic is evolved.
The residue, No. 2, contains black tin, or native tinoxide, peroxide of iron, wolfram, some sulphate of copper,and a small quantity of earthy matter. By a series ofwashing operations on the burning house floors, the per-oxide of iron, sulphate of copper, and earthy matters areremoved, and the product obtained is No. 3, which con-sists of oxide of tin, with most of the wolfram. The pro-cess is in the next place employed for the removal of thewolfram. Its proportion having been ascertained byanalysis, a quantity of sulphate of soda, or salt cake, ismixed with the ore sufficient to supply a slight excess ofthe equivalent of soda for the quantity of tungstic acidpresent; but with the sulphate of soda, must be mixedsufficient coal dust or charcoal to afford carbon or car-burettedhydrogen, for the decomposition of the sulphuricacid, and the conversion of sulphate of soda into sulphideof sodium. The mixture is exposed to heat on the bed ofthe furnace described below : a smoky or reducing flameis at first employed, but after the whole of the charge hasbeen at a red heat for some time, an oxidating flameis necessary to complete the operation. Thus the sul-phate of soda is first converted into sulphide of sodium,then the tungstic acid of the wolfram combines with thesoda, producing tungstite of soda, setting the sulphur freeas sulphurous acid, and leaving the iron in the conditionof a light finely-divided peroxide.
The product, No. 4, is drawn from the furnace into thewrinkle, or chamber beneath, and is thence removedwhilst still hot into tanks containing water, whichquickly dissolves the tungstate of soda. The solutionis run off into receivers, and the residue is removed tothe burning-house floors, where, by a series of washings,the peroxide of iron is removed, and the native oxide oftin obtained pure and ready for the smelting-house, asseen in No. 5. An ore which had fetched only 42?. perton has by this operation been so much improved inquality as to obtain 56?. per ton.
The tungstate of soda, No. 6, is obtained in the crys-talline form by the evaporation to the crystallizing point
of the solution in which it was separated from the tin.It is proposed to be used as a substitute for stannate ofsoda as a mordant for dyeing purposes.
Tungstic acid, No. 7, may be employed for the samepurpose, or for the manufacture of tungstate of thetungstous oxide with soda, a compound much resemblinggold.
The tungstate of lead, No. 8, and tungstate of lime,No. 9, are good white pigments (manufactured from thetungstate of soda), from which was also obtained themetallic tungsten, No. 10, and sulphuret of tungsten,No. 11. The former is for use in the manufacture ofmetallic alloys; the latter has been proposed as a sub-stitute for black lead. The furnace is constructed in theusual manner, excepting that a cast-iron bed has beenemployed to prevent the loss that would arise from thereaction of the silica of the bricks, the soda, and the tinoxide on each other. The fire, after passing over thebed, is also made to circulate beneath it before passingaway to the chimney.
486a Ibbetson, Capt. —Producer.
A model of the Isle of Wight, in metal.
487 Jordan, C., 37 Chapman Street , Manchester —Producer.
Case containing 176 specimens of the useful metals andalloys: —
Gold—Grain, standard, and red jewellers’.
Silver—Virgin and sterling. Platina .
Wrought iron—Best and common Coalbrook Dale;best scrap for screws and rivets ; Low Moor and commonHorton’s ; also, S. R. I. B., common, Horton’s, andKeller’s.
Steel for mills—Winders: cast steel, Turton’s, andTurton’s softened; and shear-steel, all showing surfaceand fracture.
Cast-iron—Rich Welsh pig, from Leeswood; and richScotch pig from Gartsherrie, Glengarnock, Clyde, Dal-mellington, and Dundyvan; Yorkshire , Low Moor andLeeswood; cast in sand, chilled, pig, and rich chilled;also short pig, Staffordshire, rich mottled Welsh , and.cast in sand, showing surface.
Nickel and Lead—Pure and commercial.
Copper—Tile, native, shot cast, and malleable, allshowing surface and fracture.
Tin—Block and grain.
Zinc—Chilled and sand, showing surface and fracture.
Bismuth—Chilled and sand, showing surface and frac-ture.
Antimony—Chilled, showing fracture and longitudinalsection.
Arsenic, cobalt, mercury, manganese, potassium, sodium,iridium and osmium, cadmium, and palladium.
Alloys—Copper and tin, in various proportions, show-ing surface and fracture, &c.
Alloys of copper, zinc, tin, and lead, in various pro-portions, showing the same.
Tutannia, for hardening tin, bobbin-bushes, &c.
White bush metal, of zinc, tin, and tutannia, variouslycombined.
Type metal, of tin, antimony, lead, and bismuth.
Stereotype metal, of lead, antimony, and bismuth, invarious states.
Common type and music plates, of lead and antimony.
Compositions of copper, tin, zinc, and lead in dilferentstates.
Blanched copper, antimony and copper, and Germansilver, electrum, common and plate.
Standard measures, composed of copper, tin, and lead.
Manheim gold, of copper, tin, and zinc.
Speculum metal, of copper and tin, in various mixtures.
Speculum of chilled copper and tin ; Mr. Potter’s, withtraces of arsenic, &c.