(_c_) _Lime water._ This reagent produces a white precipitate, which is extremely thick, and is easily redissolved by pure nitric acid. In this case the lime forms an insoluble tartrate, and the tartrate of antimony, thus rendered insoluble, subsides along with it. (_d_) _Concentrated sulphuric acid_ gives a white precipitate, which consists of the oxide of antimony retaining a small portion of the acid. It redissolves in an excess of the precipitant. (_e_) _Vegetable extractive_, occasions in the solution of this salt, a reddish-yellow precipitate, which has been found to consist of _oxide of antimony_, and a portion of vegetable matter. 2. _It is mixed with various alimentary substances._ If our attempts should fail to procure a solution of the salt by filtration, answering to the above reagents, we must rely upon the proof of metallic reproduction. Various circumstances may invalidate the action of our tests, such, for instance, as the ingestion of some vegetable infusion or decoction, especially that of galls, or yellow bark. With respect to the other preparations of antimony, it is unnecessary to waste our time in their consideration; the precepts already given will afford the practitioner every requisite hint for the prosecution of the enquiry. COPPER. This metal, with the exception of gold and silver, and perhaps tin, was known earlier than any other metal; but its applications were entirely confined to the arts. It was first discovered by the Greeks in the island of Cyprus, whence its name; and we learn from _Homer_, that even during the Trojan war, the combatants had no other armour but what was made of bronze, which is a mixture of _copper_ and _tin_.[305]. The external characters of the metal are too well known to require minute description. Its taste is styptic and nauseous; and the hands when rubbed for some time on it, acquire a peculiar and disagreeable odour. When melted, its specific gravity is 8·667; but after being hammered it is 8·9. It is only susceptible of two degrees of oxidation. If the protoxide be _native_, it is red; if _artificial_, orange coloured. The peroxide is black. Copper, on exposure to a moist atmosphere, becomes tarnished, absorbs a portion of its oxygen, and passes into the state of an oxide, which shortly unites with the carbonic acid of the atmosphere, and forms a greenish carbonate of copper.