188
Class 2,—CHEMICAL AND PHARMACEUTICAL PRODUCTS.South Gallery.
[United
Tincal, or natural borax. 4, Artificial tincal. 5, EastIndia refined borax. 6, English refined borax. 7, Modi-fied crystals. 8, Octahedral borax.
[The origin of boracic acid is extremely interesting.Its principal sources are the celebrated lagoons of Tus-cany , where it is obtained by a singularly simple andingenious process. It rises with steam from the heatedearth in a region where volcanic tumult is conspi-cuously manifest, and was formerly avoided by the super-stitious peasantry in its vicinity. This steam is condensedby being passed into basins partly filled with water, theboracic acid is held in solution, purified, evaporated, andcrystallized. From 10,000 to 12,000 lbs. of this acid arethus obtained every day. Boracic acid is chiefly employedas a source of borax.
Borax consists chemically, when pure, of a biborate ofsoda. It is, in its impure state, the tincal of commerce,and is obtained in large quanties from a lake in Thibet , onthe edges of which it crystallizes, and is collected by thenatives. It is also procured from lakes in China andPersia . The greater part of the borax of commerce isobtained from the saturation of boracic acid with soda.Borax is greatly used in the arts as a flux, and forglazing porcelain; also in medicine, and pyrotechny formaking “green fire.”—R. E.]
Tartaric acid, with specimens of the argols and tartarsfrom which it is made:—1, Argols, various kinds. 2,Tartars , various kinds. 3, Crystallized tartaric acid. 4,The same, in the first stage of manufacture. 5, Powderedtartaric acid.
Citric acid and the articles from which it is made:—1,Concentrated lemon juice. 2, Citrate of lime. 3, Crys-tallized citric acid. 4, Citric acid, in the first stage ofmanufacture.
Antimony and preparations:—!, Antimony. 2, Blacksulphuret of antimony. 3, Oxysulphuret of antimony.
4, Emetic tartar. 5, Antimonial powder. 6, Kermesmineral.
Silver and preparations:—1, Silver. 2, Lunar caustic. 3, Crystallized nitrate of silver.
[.Nitrate of silver, commonly called Lunar caustic , is apreparation obtained by the solution of metallic silver innitric acid. Chemical union takes place, and the solutionbeing evaporated and crystallized, a solid nitrate is ob-tained. This is, for medical purposes, fused and run intomoulds. This compound of silver, in a pure state, is ofspecial value as a re-agent to the chemist; it is alsoextremely useful in the handsof the physician and surgeon.Very pure crystallized nitrate of silver is employedfor the production of photographic pictures on paper,glass, and porcelain. When deposited on these surfaces,under peculiar circumstances, it is highly sensitive to thelight.—R. E.]
Bismuth and preparations:—1, Bismuth. 2, Oxide ofbismuth. 3, Pearl white.
Iron and preparations:—1, Iron . 2, Ammonio chlorideof iron. 3, Tartrate of iron. 4, Oxide of iron. 5,Green vitriol. 6, Ammonio citrate of iron. 7, Ammoniotartrate of iron. 8, Citrate of iron and quinine.
Mercury and preparations:—1, Mercury . 2, Oxide ofmercury. 3, Binoxide of mercury. 4, Red precipitate.
5, White precipitate. 6, Crude calomel. 7, Crystallized
calomel. 8, Calomel. 9, Hydro-calomel, sublimed underwater. 10, Corrosive sublimate. 11, Sub-sulphate ofmercury. # .
Magnesia and preparations:—1, Magnesian shale. 2,Magnesian limestone. 3, Epsom salts. 4, Carbonate ofmagnesia. 5, Calcined magnesia.
[The well-known substance called Epsom Salts is animportant preparation of magnesia. It is, in some in-stances, procured by an ingenious system of employing the
residual hydrochloric acid of alkali works, which is madeto act upon native magnesian limestone; the lime is dis-solved out by the acid, and the residual matter, consist-ing chiefly of magnesia, is dissolved in sulphuric acid,purified and crystallized. In other cases, it is largelyobtained by simply acting upon magnesian limestone withdiluted sulphuric acid; it is also obtained from the resi-dual salts of sea-water, from which common salt has beenseparated.—R. E.J
Preparations of potassium:—1, Potashes. 2, Pearl-ashes. 3, Carbonate of potash. 4, Bicarbonate of pot-ash. 5, Sulphate of potash. 6, Soluble tartar. 7, Com-mercial saltpetre. 8, Purified nitre.
[The difference in the chemical composition of the pot-ashes and pearlashes of commerce, is, that the one ischiefly a caustic form of the alkali, and the other containsmore of the carbonate. Both are alike derived from thocombustion of wood. America is the chief source of thisalkali at present. Her immense primeval forests, uponwhich the efforts of man make but little impression,present an inexhaustible source of this valuable alkali.The wood is piled up in a pyramidal heap, and the ashesare collected, partly purified, and fused. Pearlash isprepared from the “black salts,” or impure caustic andcarbonated alkali, by fusion in an open furnace. Potashis largely employed in medicine and the arts. About100,000 cwt. are annually imported into Great Britain from America alone.—R. E.J
Preparations of sodium:—1. Soda ash. 2. Subcarbon-ate of soda. 3. Subcarbonate of soda, absolutely pure.4. Sesquicarbonate of soda. 5. Bicarbonate of soda.
6. Rochelle salt in the first stage of manufacture. 7. PureRochelle salt. 8. Rochelle salt, powdered. 9. Phosphateof soda. 10. Cubic nitre. 11. Purified nitrate of soda.12. Glauber salts. 13. Hyposulphate of soda.
[The last-named preparation of soda—hyposulphate ofsoda—is a substance of great importance and peculiarinterest to the photographer. It is readily soluble inwater, and the solution dissolves, with great facility, thecompounds of silver. After a Daguerreotype picture hasbeen taken and developed by mercurial vapour, the coat-ing of iodide and bromide of silver formed on the surfaceof the plate is instantly dissolved by washing it with thissolution. The picture is afterwards dried and gilded.In the Talbotype , hyposulphate of soda is employed toremove the sensitive coating of silver, and thus fix theimpressions so as to render them insensible to the furtherinfluence of light.—R. E.]
Zinc and its preparations:—1, Zinc. 2, Oxide of zinc.3, Acetate of zinc. 4, White vitriol.
Iodine and its preparations:—!, Seaweed , yieldingiodine. 2, Kelp.. 3, Commercial iodine. 4, Resublimediodine. 5, Hydriodate of potash. 6, Biniodide of mer-cury.
Opium and its preparations:—!, Opium. 2 , Morphia.3, Acetate of morphia. 4, Muriate of morphia.
[Morphia is a powerful alkaloid, being the active prin-ciple of opium. The acetate and muriate are its mostcommon preparations for pharmaceutical purposes.—R. E.]
12 Bell, Isaac Lowthian, Washington Chemical Works ,Ncwcastle-upon- Tyne —Manufacturer.
- Specimens of Pattinson’s patent oxicliloride of ’lead;also three landscape pictures, painted with colours pre-pared from the same.