Cast Iron Borings, 4_d._

Charcoal, 3_d._

Coal tar naphtha, or mineral naphtha, 4_d._ per pint.

Copper, Black Oxide, 3_s._

" Oxychloride, 4_s._

" Sulphuret, 4_s._

Dextrine, 1_s._

Gunpowder, F, 8_d._; FF, 9_d._; FFF, 10_d._ Meal, 9_d._

Lamp Cotton, 2_d._ per oz.

Lead, Chloride, 2_s._ 6_d._

" Nitrate, 1_s._

" Protoxide, or Litharge, 6_d._

" Deutoxide, Minium or Red Lead, 6_d._

Litmus, 2_d._ per oz.

Magnesium Filings, 7_s._ per oz.

Mercury, Chloride, or Calomel, 6_s._

" Sulphuret, or aethiop's Mineral, 6_s._

Methylated Spirit, 6_d._ per pint.

Oxalic Acid, 1_s._

Plaster of Paris, 3_d._ per packet.

Potash, Chlorate, 1_s._

" Nitrate, Nitre, Saltpetre, Sal-prunella, 6_d._

Sh.e.l.lac, in Flake, 1_s._ 3_d._

" in Powder, 2_s._

Soda, Bicarbonate, 4_d._

" Oxalate, 2_s._

Stearine, Composite Candle, 1_d._

Steel Filings, 8_d._

Strontian, Carbonate, 3_s._

" Nitrate, 8_d._

Sugar, 5_d._

Sulphur, Flowers. Sublimed Sulphur, 4_d._

Vegetable Black, 10_d._

Wax, 1_d._ per cake.

Wood Naphtha, 7_d._ per pint.

Zinc Filings, 3_s._ per lb.

_CONCLUDING REMARKS._

Sublimation is the volatilization of solid substances by heat, and their crystallization by cold again into solids.

The products of sublimation (sublimates) have received the name of flowers from their soft efflorescence, or aggregation of minute spicular crystals into flakes; as flowers of sulphur, the crystallized refrigerated vapour of burning brimstone; flowers of benzoin, benzoic acid; corrosive sublimate, bichloride of mercury; sublimed a.r.s.enic, camphor, sal-ammoniac; vegetable and lamp black, the condensed fumes of burning oils and resins; soot, the flakes deposited in chimneys from the smoke of burnt wood and coals.

Distillation is the evaporation of liquid substances by heat, and their condensation by cold again into liquids.

The products of distillation (distillates) are usually termed spirits; as spirit of wine, alcohol or brandy; spirit of grain, gin, hollands, or whiskey; spirit of mola.s.ses, rum; spirit of naphtha; benzine, &c.

Water heated and cooled, combines in resemblance the effects of sublimation and distillation; aqueous vapour by congelation crystallizing into snow; and by condensation liquefying into water.

The condensation of steam into water is familiar to everyone. It is stated that in St. Petersburg, upon the sudden admission of a current of cold air into a crowded a.s.sembly-room, the vapour in the air was immediately congealed, and fell in the form of snow flakes. Probably snow might be produced artificially by driving steam into a vessel preparatively cooled below the freezing point.

Gums are the exudation of trees, vegetable mucilage thickened by exposure to the atmosphere; as gum from cherry and plum trees; gum arabic, from varieties of the acacia, Turkey, East India, Senegal, or Barbary; Turkey gum arabic is the best.

Resins are the exudation of trees, generally evergreens, essential oils insp.i.s.sated by oxygenation: as mastic, sandarac, benzoin.

Gums are soluble in water; resins in alcohol and essential oils.

Gums dry and swell up by heat; resins soften and melt.

Gum resins are partly resinous and partly mucilaginous; as lac, a.s.saftida, galbanum. In submitting sh.e.l.lac to the action of alcohol, the whole is never entirely dissolved; as the lac contains, besides the resin, a mucilage which floats about in the liquid, and renders it turbid.