[711] Alum and carbonate of lead coloured with Brazil and peach woods.
Various arsenical preparations are used to kill flies; the active principle of the brown “papier moure” is arsenious acid. A dark grey powder, which used to be sold under the name of fly-powder, consisted of metallic arsenic that had been exposed some time to the air.
Fly-water is a strong solution of arsenious acid of uncertain strength, sweetened with sugar, treacle, or honey. Another fly-poison consists of a mixture of arsenious acid, tersulphide of arsenic, treacle, and honey.
(4) Quack and other Nostrums.—The analyst may meet with several quack preparations for external use in cancer. A celebrated arsenical paste for this purpose is composed of:—
| Arsenious Acid, | 8 | per cent. |
| Cinnabar, | 70 | „ |
| Dragon’s Blood, | 22 | „ |
Frères Come’s Cancer Paste is composed of arsenious acid, 1; charcoal, 1; red mercury sulphide, 4; water, q. s.
The tasteless “ague drops” used in the fen countries are simply a solution of arsenite of potash.
Davidson’s Cancer Remedy consists, according to Dr. Paris, of equal parts of arsenious acid and powdered hemlock.
In India, arsenic given as a medicine by native practitioners, or administered as a poison, may be found coloured and impure, from having been mixed either with cow’s urine, or with the juice of leaves, &c.[712]