LESSONS IN < HIM is Ik V. 





LEMONS IN CHEMISTRY. XXIV. 



METALS rUOPEIl-continiMd. 



Tit. 

 SYMBOL, Di COMBINIXU WUUHT, 210 Sracinc GRAVITY, 9-8. 



Miotul exhibits a resemblance to arsenic and antimony, and 

 is thoruforo sometimes claused with them in one group. It 

 rhi.'fly in a native state in quartz rock, and in found in 

 ! ( iiTtuany. To extract the metal from the ore, it u only 

 necessary to raise the temperature until the binmuth fuses, and 

 in its li. pi ill condition it leaves its matrix and sinks to the bottom 

 furnace. The metal has the appearance of load, perhaps 

 its a little warmer tint ; it is hard and brittle ; at 264 

 i \-iit. it m?lta. If the crust of a vessel of molten bismuth, par- 

 tially cooled, be broken, and the still liquid metal poured out, 

 the cavity will be found lined with peculiar hollow cubical crys- 

 tals, which present the appearance of " the Greek pattern." 

 The crystals are not true cubes, but rhombohedra with large 

 angles, only being 2 20' from right angles. 



At the moment of solidification this metal expands consider- 

 ably, hence it is always used in making alloys which are em- 

 ployed in taking casts. The well-known fusible metal, which 

 ni 'Its at a temperature a little below that of boiling water, is 

 composed of two parts of bismuth, one of lead, and one of tin ; 

 before this alloy fuses it becomes a paste, and when in this con- 

 dition if a medal be pressed into it a perfect cast is obtained. 

 Tno expansion of the alloy on solidifying permits the medal to 

 uoved with ease. It is in this manner that the cliquee 

 moulds used in elect-retyping are produced. Nitric acid readily 

 oxidises bismuth, and dissolves the oxide it forms. 



Hydrochloric and sulphuric acids likewise dissolve the bis- 

 muthous oxide ; but upon adding water to these solutions the 

 water displaces a portion of the acid from the salt, and the 

 double salt thus formed falls as a precipitate. 



Bismuttwus 0-ride (Bi 3 O 3 ) is a yellow powder produced when 

 the metal is roasted in the air. 



Bismuthic Oxide, or the Peroxide of Bismuth (Bi 2 O 5 ), is pro- 

 ured by acting on the former oxide by potash. On passing 

 ?hlorine, a red precipitate falls ; this is washed with nitric acid, 

 to remove any traces of the lower oxide. 



This red powder is the hydrated peroxide; when heated it 

 tfives up its water and becomes brown. As in the case of 

 antimony and arsenic, there seems to bo an intermediate oxide 

 which may be considered a compound of the two. 



Bismuthic Sulphide (Bi 4 S 3 ) occurs native as Bismuth Glance. 

 It may be artificially produced by melting sulphur and the metal 

 together, and it falls as a black powder when a current of 

 sulphuretted hydrogen is passed through a solution of a bismuth 



Milt. 



Bismuthic Chloride (BiCl 3 ) is produced when bismuth is 

 he.ited in an atmosphere of chlorine. It resembles antimonic 

 chloride, is very deliquescent, and capable of being distilled. A 

 large quantity of water decomposes it into hydrochloric acid 

 and an oxy-chloride of bismuth, known as pearl white, thus 

 SBiCl, + 4H,O = Bi,O,C!,,2H,O + 6HC1. 



The salts of bismuth present no marked characters ; they 

 become milky when diluted with water. Iron, zinc, copper, and 

 tin throw down bismuth in a metallic state from its solution. 

 The metal is easily reduced from its salts on charcooi before the 

 blow-pipe. It appears as a brittle metallic bead surrounded oy 

 the yellow bismuthous oxide. 



COPPER. 



STMBOL, Cu COMBINING WEIGHT, 63-5 SPECIFIC GRAVITY, 8'9. 



This useful metal occurs native in many localities, as dendritic 

 copper, resembling a mass of rootlets ; but in the neighbourhood 

 of Lake Superior native copper is found in large masses. 



The ores of copper are numerous. That which is chiefly 

 ivorked in this country is copper pyrites (Cu 9 S + Fe,S s ). Its 

 chief deposit is in Cornwall. 



Extraction of the Metal. This is effected by exposing the ore 

 heated on the hearth of a reverberatory furnace to the action 

 of the air. The copper becomes a sulphide, whilst the iron 

 becomes an oxide. This oxide is removed with the quartz, as a 

 fusible slag. 



During this process the furnaces emit a dense cloud, known as 

 copper smoke. It contains fumes of arsenious, sulphiiroua, sul- 

 phuric and hydrochloric acids, and is consequently extremely 



73 N.E. 



deletorioiw. After too ore hs bean submitted 

 process for some time the beat in railed, and the futon of the 

 oro determined. The copper sulphide mixed with come iron 

 Kulpliido sinks to the bottom of the furnace, forming the malt, 

 which in then drawn off into water, by which means it is grann- 

 lated. This coarte metal is again roasted, and the ""^"kf 

 iron thus oxidised ; oro rich in silica i* added, and the whoU 

 fused. The oxide of iron and the silica form a slag ; and the 

 copper in the form of a subsolphide fine metal (0,8) is 

 drawn off and oast into pigs. It only remains to free the metal 

 from the sulphur ; thU is accomplished by submitting the pig* 

 to a heat in a reverberatory furnace just insufficient to fuse 

 them. The metal at the surface thus becomes oxidised, and 

 when fusion takes place this action occur* 

 CutS + 2CnO = 80s ' T * c ' u - 



Thug the copper is obtained. It still reqnlres tc be refined. 

 For this end it is again fused, in order to oxidate the last traces 

 of foreign metals, which are removed as slags ; and to reduce 

 any oxide of copper, the trunk of a young tree is thrust into 

 the molten mass, the gases liberated from it deprive the oxide 

 of copper of its oxygen, and thus the metal is procured in its 

 pure state ; this last process is termed poling. 



The appearance of copper is well known, but when pore, an 

 produced by the electrotyping process, it possesses a beautiful 

 pink colour. It is very tenacious, ductile, and malleable. It 

 melts at about 1090 Cent., and is capable of some volatilisation, 

 imparting a green tint to the flame. At ordinary temperatures 

 air has no action upon copper, but if heated a cupric oxide is 

 formed, which, as it contracts more slowly than the metal be- 

 neath, comes off in scales. If ignited, finely-divided copper will 

 burn like tinder into the black oxide. 



Leaves of this metal, as we have seen, will burn in a jar of 

 chlorine. All the alloys in which copper is a constituent have 

 been noticed. 



Cuprous Oxide (Cn.,0), or the suboxide, occurs native a* 

 " octahedral copper ore." Its colour is red. It may be artifi- 

 cially prepared in several ways ; the most ready is, perhaps, by 

 boiling a solution of copper sulphate, sugar, and caustic potash, 

 in excess ; the oxide foils as a red powder. It forms with acids 

 cuprous salts, which readily take oxygen from the air, and be- 

 come cupric salts. It is chiefly used to stain glass a deep red. 

 When in a hydrated state it forms with ammonia a colourless 

 solution, which offers a delicate test for oxygen, for it absorbs 

 that gas and turns blue. 



Cupric Oxide, the Black Oxide (CnO), is formed when heated 

 copper is exposed to the action of the air. It falls as a light 

 blue powder in a hydrated state, when potash is added to the 

 solution of a cupric salt; this powder, when heated to 100, 

 loses its water and becomes dark brown. 



It is of great service in analysis to furnish oxygen in a known 

 quantity, to complete the combustion of organic bodies. 



The cupric salts which this oxide forms with acids are usually 

 green or blue, and colourless without water. Cupric oxide stains 

 glass a beautiful green. 



With ammonia it forms a blue solution, with which the cha- 

 racteristic bottles of a chemist's shop window are filled. 



Copper Sulphate, or Blue Vitriol (CnSO 4 + 5H.O). has the 

 greatest commercial importance of all the cupric salts. It 

 crystallises in large blue crystals ; when heated it parts with 

 its five molecules of water of crystallisation, and becomes a 

 white powder. This powder is useful in discovering the pre- 

 sence of moisture, as it turns blue when combined with water. 

 This salt is formed by the action of sulphuric acid on copper ; it 

 is largely used by the calico-printer, and is the souroe of all the 

 copper pigments. 



When ammonia is added to its solution, a greenish bv,;c sul- 

 phate of copper falls which is readily dissolved in an c\ 

 the alkali from the formation of salt of a fine blue K>!OUI, 

 which may bo got in crystals, and has this composition 

 CnSO 4 ,H t O,4NH 4 . This salt imparts the mauve tint to pyro- 

 technic firea. 



Cupric Nitrate (Cn,2NO s ) crystallises with six molecules of 

 water in bhie rhomboidal prisms, which are deliquescent. It is 

 easily procured by acting on copper with nitric a_id ; in this 

 action nitric oxide is liberated, thus 



3Cu + 8HNO, = 3 (Cu.SNO,) + 2X0 + 4H,O. 



Cupric Carbonate is found mixed with various quantities of 



