Phosphorus has the property of re ducing the oxides of silver, and of pre cipitating them from this solution in acids, in the metallic form. Sulphur combines readily with silver, both in the dry and humid way. By stratifying in a crucible, plates of silver alternately with sulphur, and melting them rapidly, a deep violet-coloured mass is obtained, which is more fusible than silver, brittle, crystallized, and has a metallic lustre. It may be cut with a knife, and has a good deal of resemblance to vitreous ore of silver. When this sulphuret of silver is exposed to heat for a considerable time, the sulphur is gradually dissipated, and the silver remains pure and ductile. Sil ver combines very readily with sulphur, when it is long exposed to those matters which gradually deposit this substance. This effect is immediately produced when silver is brought into contact with stilphu. rated hydrogen gas, or when it is im mersed in water, impregnated with this gas, as in natural sulphureous waters. Dr. Thomson thinks it is owing to the same cause, that a silver spoon is tarnish ed by a boiled egg, and particularly if the egg has begun to spoil. Sulphuretted hydrogen gas, which is exhaled by the egg, is decomposed ; the sulphur com bines with the silver, and forms a thin layer of sulphuret of silver, which is of a dark or violet colour ; other writers have ascribed this to the action of galvanism. The same thing happens when silver is exposed in places that are much frequent ed, as in churches and theatres. Silver
forms alloys with most of the metals, and salts with the acids. Hence its use in coinage, and also in medicine.
Antimonial silver, in colour, is between silver white and tin white ; sometimes in clining more to the one, sometimes more to the other. It occurs massive, dissemi nated and crystallized. Specific gravity between 9 and 10. Heated on charcoal before the blow-pipe, the antimony is vo latilized with the odour peculiar to it, and there remains a mass of silver, sur rounded with a brown slag. It consists, according to Vauquelin, of Silver Antimony - - - - 22 100 It occurs in veins which are composed of calc-spar, heavy-spar, and is accompa nied with lead glance and native silver. It is distinguished from native silver by its brittleness, and a foliated fracture.
Arsenical silver is of a tin white colour, which passes into silver white, and verges on light lead grey. It is always more or less tarnished with a blackish colour. It occurs massive, disseminated and globu lar. It consists of Arsenic - - - - 35 Iron 44.25 Silver 12.75 Antimony - - - 7 100.
Before the blow-pipe the arsenic and antimony are volatilized, and they emit a garlic-like smell. The silver remains more or less pure in shape of a globule. This is a very rare mineral, and does not tarnish so quickly as native arsenic ; it passes on the one side into native arsenic ; on the other into native silver.