194
Class 2.—CHEMICAL AND PHARMACEUTICAL PRODUCTS.South Gallery.
[United
pots are then built up in alternate layers, with spenttanner’s bark, until a stack is formed; each layer of potsbeing covered with boards. The fermentation, which soontakes place in the tan, serves the double purpose of fur-nishing carbonic acid, and raising the temperature of thestack, which reaches 140° Fah. After a lapse of six oreight weeks the metallic, or blue lead, as it is called, isconverted into porcelain-like masses of white lead, whichare levigated in water, washed and dried. About 16,000tons are annually made in England by this process. Avery small quantity of acetic acid suffices for the conver-sion of a large amount of metallic into white-lead; as, afterit has combined with a portion of lead oxide to formneutral acetate of lead, this salt dissolves another atomof lead oxide, which is removed by the carbonic acid ascarbonate of lead, and the neutral acetate set free, againto take up a fresh portion of newly-formed oxide of lead,produced by the action of the air on the metallic lead.Most of the new processes depend on similar reactions,with this difference, that oxide of lead (litharge) is em-ployed instead of metallic lead: it is either made into apaste, with a small quantity of acetate of lead and water,or else dissolved either in a solution of neutral acetate, orneutral nitrate of lead, and submitted to the action ofcarbonic acid, produced by the combustion of coke orcharcoal, which precipitates the dissolved litharge, leavingthe acetate or nitrate at liberty to dissolve fresh portions.Another of the new plans consisted in precipitating aneutral salt of lead (the nitrate, for example) with analkaline carbonate.—W. D. L. R.]
60 Johnson, J. R., 12 Banhide —Inventor.
Extract of munjeet. Patterns of calico printed and
dyed with the extract. Extract of madder. Patternspnnted “topically” with the extract. Exhibited to illus-trate a new process of extracting, economically, thecolouring principle of the Rubiacece.
Printed calicoes, to illustrate a new process of madderdyeing, which is intended to replace garancine.
Pieces of calico printed topically with extract of madder.
[Extract of munjeet, or munjeeth, is obtained fromthe roots of Rvhia cordifolia, an East Indian plant. It isimported into England from Calcutta . It is not solargely used as madder, which is furnished by the rootsof another plant allied to Rubia cordifolia. The colourproduced is said not to equal that of madder in brillianceand permanence.—R. E.]
61 Scott, Langston, 41 Moorgate Street —
Manufacturer.
Large vase and small glasses containing white oxide ofzinc.
Various small painted boards.
Patent white zinc is principally used for house-paintingin lieu of white-lead as being less noxious; but may beapplied in the manufacture of crystals, paper-staining,card-enamelling, bleaching of lace, glazing of ware, forthe down of artificial flowers, &c. It possesses greatwhiteness, gives a fresh tone to all colours, renders thepaint or material prepared impervious to the action ofgases damp, &c., reflects artificial light, and preservesthe materials. It is produced by destructive distillation,from zinc ore, or spelter, which is. principally importedin large flat slabs from Silesia, Galicia, and Prussia: Rus-sia, Belgium , and China send smaller supplies; the greatEuropean depot is Hambui’gh.
[Oxide of zinc is now largely employed instead ofceruse, and is much less noxious than that preparation oflead.—R. E.]_
62 Davy, Mackmurdo , & Co., Berimndsey —
Manufacturers.
Samples of carbonate of ammonia; corrosive sublimate;
calomel; benzoic acid; citric acid; gallic acid; oxalic acid;salt of sorrel; acetate of zinc; nitrate of silver; chlorideof barium; nitrate of baryta; tartar emetic crystals; sul-phite of soda; nitrate of ammonia; acetate of lead; glyce-rine; bisulphate of mercury; red precipitate; calomel inpowder.
63 Dauptain, Gorton, & Co., 17 Wharf Road,
City Road —Manufacturers.
Four samples of ultramarine.
64 Estcourt, Samuel, 2 Green Terrace , New River Head
—Inventor and Manufacturer.
Sample of refined Indian blue, for the laundry.
65 Coppock, John, Bridport —Inventor.
A chemical liquid for imparting the colour of mahoganyand rosewood to common woods. A specimen of theprepared wood, polished, with a bottle containing theliquid; the sides of the block are left unstained, to showthe natural wood.
[The liquid commonly employed for staining wood soas to communicate to it the appearance of antiquity is acaustic solution of potash. The same effect is also pro-duced by the use of soap leys, simply in consequence ofthe free alkali contained in that liquid. Other chemicalfluids are likewise used for the same purpose.—R. E.]
66 Bell, Geo., & Co., 2 Wellington Street, Goswell Street
—Manufacturers.
Mineral paints, which quickly dry under water, and onmetals exposed to extreme heat. They are suitable forships’ bottoms, or for damp walls.
67 Leifchild, J., High Hill Ferry, Upper Clapton —
Producer.
Specimens of dyes for silk.—Carmine from safflower,blue from indigo, and blue from prussiate of potash.
[Safflower is yielded by a plant known botanically asCarthamus tinctorius, belonging to the Asteracecc. Theflower is alone used in dyeing. The plant is an annual,cultivated in Egypt , the Levant, &c.—R. E.]
68 Marshall, John, Leeds —Manufacturer.
Nos. 1, 2, & 3. Acid and neutral extracts of indigo.
4 & 5. Carmine and liquid extract from purified in-digo.
6. Refined indigo.
[Indigo is the produce of plants belonging chiefly todifferent species of indigo-tree; it is also obtained, to asmaller extent, from others. The state in which it existsin the juice of these plants is not well understood. Itappears to be in the form of a colourless, soluble com-pound, and is generally obtained by fermenting thebruised plant, during which ammonia is evolved, and ayellow liquor obtained, which, on the addition of lime-water, and exposure to the air, deposits the insolubleblue substance called indigo. For the purposes of dyeing,the indigo is dissolved in sulphuric acid, with which itforms a distinct chemical compound.—E. F.]
7 & 8. Red and blue orchil paste.
9 & 10. The same, of medium quality.
11 & 12. The same, of fine quality.
13 8c 14. Red orchil liquor for silk dyeing.
15 & 16. Concentrated red and blue orchil liquor.
17 & 18. Cudbear.
19 & 20. The same, of good and best quality.
21 & 22. Violet carmine, and best concentrated cud-bear.
23, 24, 25, & 26. Valparaiso, Angola , Madagascar, andCape de Verd orchella weed.
[Those substances are prepared from various lichens,amongst which the Roccella tinctoria , R. corallina , Lecanora