In a general sense these are substances which promote the fusion of minerals, but particularly which cleanse a reduced metal, by assisting its separation from its impurities. They also serve to defend it from the action of the air, and some of them assist in the reduction of oxides.
Into an earthen crucible, heated sufficiently hot to cause feeble combustion, but not to fuse the flux, throw successive portions of a mixture of 1 part of nitre, and 2 of crude (or cream of) tartar. Keep the flux in a close bottle.
Into a large earthen crucible, heated to redness, throw successive portions of a mixture of 2 parts of nitre and 1 of tartar. Keep it as the last.
Crude Flux, is the mixture of nitre and tartar, before deflagration.
Fresenius's Flux, for reducing sulphuret of arsenic. Dry carbonate of potash 3 parts, cyanide of potassium 1 part.
Mr. Taylor's Flux. Saturate a solution of tartaric acid with carbonate of soda, evaporate to dryness, and calcine in a covered platinum crucible.
Sal enixum (the acid sulphate of potash left in distilling nitric acid), sandiver or glass-gall, fluor spar, limestone, etc., are also used as fluxes.
A common poison for flies consists of white arsenic, or King's yellow, with sugar, etc, but the use of such compounds may lead to fatal accidents. A sweetened infusion of quassia answers the same purpose, and is free from danger. Pepper, with milk, is also used; and also some adhesive compounds by which they are fatally entangled. Papier moure contains a large quantity of arsenic.
On 100 grs. of pulverized nitrate of silver, in an open glass vessel, pour first an oz. of alcohol, and then as much strong nitrous acid. The mixture boils, and gives out ethereal vapours. When all the powdered nitrate has taken the form of white clouds, cold distilled water must be added to sustain ebullition, otherwise the fulminate will be dissolved. Collect the powder on a filter, and dry it at a low temperature. Dr. Turner directs 1 part of silver to be dissolved in 10 of nitric acid, at a gentle heat, 20 parts of rectified spirit to be added, and the mixture warmed. When it begins to boil, set it aside to cool, collect and wash the crystals on a filter, and carefully dry them. This is more violent and dangerous than fulminating mercury.
See Fumigatio, Pocket Formulary, for their medicinal uses. Though not strictly belonging to this place, it may be useful to give a few directions for the management of these important agents, as disinfectants and purifiers.