CYass X.]
MINING MACHINERY—LEAD AND IRON COLLECTIONS.
9
a part of their establishment, consisting of two furnaces.Tiie gases conveyed from these furnaces between six andseven feet below the top are conducted into a smallchamber, where they are mixed with hot air, and are thenceconducted under the boilers of the steam-engine they areintended to feed. According to the statement of theexhibitors, no other fuel is needed for a sixty-horseengine ; and they add, that the current of gas beingregulated, the heat is uniform, and the boilers last muchlonger than when heated with coal, which they attributeto the absence of those irregularities of temperature pro-duced when coal is used, and the doors of the furnace areconstantly being opened and shut. The exhibitors haveadded to this model samples of the pig and other iron pro-duced at their establishment: these are ofvery good quality.Model of a Contrivance for Opening and Shutting
the Ventilating Doors of Mines by means of a
system of Levers. (418, p. 150.)
Mr. Robert Mills has introduced into the coal-minesof Foxhole, near Swansea, an arrangement of levers bywhich the doors connected with the ventilation of themine are opened and closed by the mere passage of thewaggous through them. During 22 years that this me-thod has been in use, there has not been a single explosionin the Foxhole mines. The Jury, considering that thisarrangement provides against the negligence of workmen,ensures good ventilation by keeping the doors regularlyclosed, and is an important improvement in practicalmining, have awarded a Prize Medal to this exhibitor.
Safety Fuse for Mining Purposes. (424, p. 150.)
The safety fuses here exhibited by Messrs. Bickford,Smith, and Davey, consist of a small thread of fine gun-powder twisted into the middle of a rope, of which thestrands have been separately tarred, the whole rope beingafterwards also tarred. The different kinds of safety fusevary according to the coating employed to enable them toresist the pressure of water.
Safety fuses, invented 15 or 10 years ago, have sincethen been of great service, not only on account of the ac-cidents they have prevented, but by the facility with whichthey allow of shots being fired in mines, under water, andin ice. They are lighted in the usual way, and communi-cate with the charge after an interval determined by thelength of the fuse. They are not injured by exposure towet, and effect a saving in the quantity of powder required.
Apparatus for Changing the Direction of Rotationin Machinery. (472, p. 1G6.)
The model of stamping machinery applied to crushingcopper and tin ores in Cornwall exhibits a peculiar me-thod for reversing the direction of rotation, the inventionof Mr. R. Hosking, to whom the Jury has adjudged aPrize Medal.
Obelisks of Coal and Building Stone, &e. (430,pp. 459 — 401.)
The carboniferous system in Wales contains a verycompact fine-grained grit, which famishes an extremelysolid freestone, resisting the action of fire. The Aber-earn and Gwythen Collieries Company has exhibited anobelisk of this stone (Aberearn), having the faces dif-ferently worked, in order to show the grain of the stoneand the manner in which it may be cut.
The same exhibitors send also the different varieties ofcoals from their locality, and the tools used in quarryingthe Aberearn stone, as well as a description of the methodsadopted by them in deepening the shafts of mines. Severalof the tools are of novel shape, and some appear to be welladapted for us_p. The mode of deepening shafts has alsoattracted the attention of the Jury as reducing the cost ofthis operation. This double reason has induced them toaward a Prize Medal to Mr. Ebexezer Rogers, whorepresents the Abercarn and Gwythen Company.
Separation of Wolfram from the Oxide of Tin inthe Preparation of Tin Ores. (485, p. 172.)
Mr. Robert Oxland, of Plymouth, who has inventedthis method of separating wolfram from the oxide of tin,has exhibiting a complete collection illustrating the suc-cessive operations of which it consists.
therefore but little greater than oxide of tin, which is about6'5, it is welluigh impossible to separate the two mineralsby washing, and all that can be done by the usual modesof mechanical preparation of tin ores is to bring them toa state in which they are mixed with wolfram only.
After determining by analysis the proportion they con-tain, a sufficient quantity of sulphate of soda is added toensure an excess of soda relatively to the tungstic acid,and the whole is then mixed with charcoal dust to decom-pose the sulphuric acid, and pass the sulphate of soda intothe state of sulphite. The mixture is placed in a rever-beratory furnace, of which the bed is of cast iron, and isfirst exposed to a smoky or reducing flame; but afterwardsto complete the operation it is necessary to have an oxi-dising flame.
The sulphate of soda being transformed into sulphide,the tungstate of iron is decomposed, and the tungstic acidcombines with the soda, leaving the iron in the conditionof a very fine powder. The tungstate of soda is after-wards dissolved out, and the oxide of tin separated from theoxide of iron by washing. The solution of tungstate ofsoda is evaporated, and the salt, obtained in a crystallinestate, is sold as a mordant for dyeing purposes, replacingwith advantage the stannate of soda. The tungstic acidmay also lie obtained, and the value of these products aresufficient to repay the cost of the process, at the same timeraising the value of the ore, so that a sample which hadbeen only worth 42/. per ton was sufficiently improved tobe worth 5G/. There is, therefore, a great improvementin the preparation of the ores of tin, for which a PrizeMedal has been awarded by the Jury.
Collection illustrating the Manufacture or Lead.(494, p. 173.)
Mr. Joshua Byers, proprietor of a lead mine in thecounty of Durham , worked by himself, has exhibited aseries of his products, which includes the lead ores as ob-tained from the Grass-hill Mine, the ores prepared forsmelting, the lead in pig, sheet lead, and lead piping.There is also a cake or button of silver, and the differentqualities of litharge obtained during cupellation.
The slags which accompany the common and refinedlead illustrate the successive conditions through which theore has to pass in obtaining the various merchantablecommodities.
Collection illustrating the Iron Trade. (411,pp. 148, 149.)
Messrs. W. Bird and Co. exhibit an extensive collec-tion of specimens of iron, illustrating the makes of dif-ferent localities, from the lowest-priced “ pig/’ manufac-tured from black-band by the use of the “ hot-blast,” tothe more expensive, made from the argillaceous ores by“ cold-blast.” Also specimens of these severally decar-bonized into refined metal, and manufactured into thedifferent descriptions of bar-iron in Staffordshire, Wales ,and Scotland . The several stages of the manufacture arc-illustrated by exhibits of railroad bars, boiler-plate, chain-cables, tin-plates, terpe-plates, boiler-tubes, wire, &e.
This collection gives a very correct and instructive ex-emplification of the extent and variety of the iron manu-facture of Great Britain, the descriptions exhibited beingthose of the sorts in every-day demand for home con-sumption and for export. It represents an annual makeof not less than 500,000 tons.
Forming part of the collection arc two articles deservingof special notice:—the one a round bar of iron, rolled atthe works of John Bagnall and Sons, of West Bromwich,20 feet 1 inch long, 7 inches in diameter, apd weighing2,644 lbs.; the other a cylindrical iron tube, 12 feet longand 7 inches in diameter, drawn by a patent process atthe works of Selby and Johns, of Smethwick . The Juryaward a Prize Medal to Messrs. W. Biri> and Co. for theirwell-arranged and extensive collection, and to Messrs,J. Bagnall and Sons and Messrs. Selby and Johns,respectively, for the excellence of their productions.
Specimens of Sheet Iron coated with Tin, Zinc
with Lead , &c., by tiie Galvanic Process. (430,P- 16 L)
'I hese specimens, exhibited by Messrs. Morfavood and