ARSENIC, ANTIMONY, BISMUTH. COPPEE AND LEAD. 259 



turned into a large quantity of water, the salt loses a part 

 of its nitric acid, and so becomes basic, and is called a sub- 

 nitrate. This appears in the form of a white precipitate. 

 This has been sometimes used as a cosmetic. It would be 

 dangerous for a lady who had used it for this purpose to 

 attend a chemical lecture at which any sulphuretted hydro- 

 gen should escape, for this gas blackens at once this salt. 



366. Copper. This metal is next to iron in strength. It 

 is one of the very few metals which have a decided color. 

 It is very malleable and ductile, and is therefore much used 

 in the forms of sheet and wire. It is largely used in sheath- 

 ing ships. It is a constituent of many alloys, as brass, 

 bronze, German silver, etc. Gold and silver, both in coins 

 and articles for use, are alloyed with copper, to give them 

 the requisite hardness. Native copper is found in abun- 

 dance in the neighborhood of Lake Superior. A mass of it 

 has been taken thence to Washington which weighed 3704 

 pounds, and a mass has been uncovered in one of the mines 

 which has been estimated to weigh 200 tons. The metal is 

 also largely obtained from copper pyrites, a double sul- 

 phide of iron and copper that is, an ore in which the sul- 

 phur is chemically combined with both of these metals, the 

 particles of the .two sulphides being most intimately min- 

 gled together. There are also other ores of copper the 

 pure sulphide, red oxide, carbonate, etc. There are two 

 oxides of copper the monoxide, which is black, and the 

 suboxide, which is red. The latter is used in the manu- 

 facture of glass, giving it a splendid ruby-red color. 



We have already named many of the salts of copper; 

 the sulphate sometimes called blue vitriol forms beautiful 

 blue crystals containing water. It is used in calico-print- 

 ing and in the manufacture of green pigments, some of 

 them containing arsenic, as you have just learned. Ace- 

 tate of copper, sometimes called verdigris, is another green 



