SOS
This valuable discovery has rendered the art of bleaching bothfimple and easy ; and to the manufacturers of linen and cottonthe most important consequences have resulted, as they can whit-en goods in a few hours which formerly required long exposureto the sun and air.
Mr Charles Tennent obtained a patent for this discovery; andhe manufactures bleaching salt, as this article is denominated, togreat extent, at St Rollock’s, near Glasgow.
4. Nitric Acid . —This acid is known in commerce under thename of aquafortis; and is obtained by the distillation of sul-phuric acid and nitre, or saltpetre. It is extensively employedin the arts, especially by dyers and calico-printers. It is not onlyused by itself, but, combined with the muriatic, it forms nitro-muriatic acid, and termed aqua regia, from its power of dissolv-ing gold ; and 1 by means of which, with tin, the beautiful scar-let colour is produced on woollens. In the various processes ofetching on copper, nitric acid is a powerful agent, as well as inthe gilding and frosting of metals.
5. Fluoric Acid . —This acid is obtained by the same processas muriatic acid, only substituting in the retort, which must bemade of lead, fluor spar, instead of common salt. It has beenapplied in Glasgow to frost window glass used for cotton worts.
6- Pyroligneous, or Wood Acid. —This acid is produced by thedistillation of wood in a cast-iron retort. The gas passing througha worm contained in a refrigeratory, is condensed in the samemanner as common spirits. The wood is left in a charred statein the retort, and may be used for any purpose to which char-coal is applicable. This acid is a powerful solvent of iron; andbeing only 4d. per gallon, is now' almost universally used formaking acetits of iron, or iron liquor ; and acetite of alumine, ared liquor, for calico-printers and dyers. There are seven worksfor making pyroligneous acid in Scotland ;—four at Camlachie,Tradestown, Brownfield, and Lanark, in Lanarkshire ; one neatTorryburn in Fifeshire ; and two at Milburn and Corcale i®Dumbartonshire. One ton of wood affords about 90 gallons °tacid, and 10 gallons of tar. The latter comes over with thea-cld ; but being heavier, readily subsides, and is separated.
7. Prussiate of Potass. —This article is manufactured to consi-derable extent at Campsie in Stirlingshire. It is produced fromanimal matter, as blood, hair, and hoofs of cattle, woollen rags,&c.; and the manufacture consists in mixing the substances withalkali, and calcining the composition until it resembles coatWater is then added to dissolve the saline part, and the lixiviumobtained is prussiate of potass. Either in this, or in the crystallized state, it is sold to calico-printers, who use it to produce ablue colour, which is as beautiful, though less durable, than tliafrom indigo. Prussian Blue is also manufactured at the samework, to great perfection, and considerable extent; but it is usechiefly as a pigment.