IN < 1IKM1 



177 



LESSONS IN CHEMISTRY. XXI 



METALS ,,td. 



CADMIUM. 

 SYMBOL, Cd COMBINING \VI.L. m, l!J Sr> . me GRAVITY, 87. 



AT the commencement of the distillation of zinc, a brown smoke 

 n Been to issue from the crucible; this ia the oxide of 

 fuiltnium. The metal in rare. It reaembleH tin in appearance, 

 so soft M to leave a mark upon paper. It melta at 

 :;.' (,),(., and ia volatile. Though generally found asso- 

 .vith sine, it la easily separated from that metal by sol- 

 hydrogen, which precipitates from an acid solution the 

 \ellu\v sulphide of cadmium, which ia used as a paint. 

 l'!i. n.tliilf of ra.lmium ia used for iodising collodion for the use 

 M photographer. 



COBALT. 



SYMBOL, Co COM HIKING WKIGHT, 587 SPECIFIC ORAVITT, 8'5. 



This metal is found associated with arsenic, nickel, manga- 

 nese, iron, ami cop- 

 per, in uiv.s more or 

 IMI complicated. it 

 litti.'iiltoi ex- 

 traction. It i 

 to be of a light-red 

 colour, requiring a 

 high temperature 

 fusion. It 

 possesses great te- 



and exhi- 

 bits magnetic pro- 

 perties. It is readily 

 1 by nitric 

 acid, and even by 

 exposure to the air. 

 It owes its commer- 

 cial value to the bril- 

 liant colours which 

 the salts of cobalt 

 It forms 



two oxides, namely, 

 the protoxide (CoO), 

 and the sesquioxide 

 (Co g O s ). The former 

 is soluble in acid. 

 The concentrated 

 solution is of a beau- 

 tiful blue, but when 

 diluted, pink. This 

 oxide will also com- 

 bine with bases. 

 With the hydrate of 

 potash it forms a 

 blue compound; with 

 magnesium nitrate, 

 a pink. Thenard's 

 blue is its combina- 



tion with alumina; and with the oxide of tin is formed Einman's 

 green. However, cobalt chiefly finds its way into commerce as 

 matt, which is blue glass coloured by this oxide. It is chiefly 

 manufactured in Saxony. The ore which, besides cobalt, con- 

 tains several metals in combination with sulphur and arsenic, is 

 roasted sufficiently to cause the cobalt to become oxide. This 

 .is effected at a temperature too low to disturb the other combi- 

 nations in the ore. Four parts of this roasted ore, with ten 

 of quartz and four of potassium carbonate, ore slowly melted in 

 a furnace. The cobaltic oxide combines with the fused sili- 

 cate of potash, and a blue glass is formed. The other con- 

 stituents of the ore fall to the bottom of the crucible, and make 

 that brittle, metallic mas, called speiss, from which nickel is 

 extracted. The blue glass is poured out into cold water, by 

 which it splits into fragments, which are afterwards ground 

 between granite stones under water. The water is allowed to 

 flow out, as the grinding proceeds, into depositing vessels, 

 each being filled by the overflow of the- one above it. It will be 

 ovidi-nt that the finest powder will be found in that vessel 

 furthest from the mill. Smalt is used in the manufacture of 

 paper-hangings, and to some extent by laundresses, to correct 



64 N.E 



FIG. 50. SECTION OF A BLAST FUBNACE. 



and neutralise the yellow which tinge* linen. The salt* of 

 cobalt aro of little other interest When crystallised they are 

 red ; when anhydroua, blue. Their solution*, when concentrated, 

 aro blue, and on being diluted, pans through red to pink. When 

 a cold red solution ia heated, it becomes blue again. 



The presence of cobalt is easily detected by the interwo bin* 

 it imparts to a bead of borax in the blow- pipe flame. A isola- 

 tion of its salts with potaah become* blue, and by an exoe* of 

 the alkali, pink. Ammonia has the same effect, but the ; 

 tato ia readily dissolved in an excess of the liquid. 



NICKEL. 

 SYMBOL, Ni COMBHUMG WEIGHT, 587 Sracinc G*ATITT, fr5, 



Nickel ia a white, silver-like motal ; hard, yet ductile. It* 

 magnetic properties are more marked than those of cobalt, 

 to which metal it presents a very remarkable analogy. -Nickel 

 is extracted either from the speiaa mentioned above, or from tlie 

 ore Icupfcrnickel , in which it ia combined with araenic. It in 

 chiefly of value on account of its property of whitening brass, 



thus producingpocik- 

 fong or German sil- 

 ver. Like cobalt, it 

 forma two oxides : 

 NiO, the protoxide, 

 the salts of which 

 are green, and when 

 anhydrous, yellow ; 

 and Ni.O,, the aes- 

 quioxide, of which 

 no salts are known. 

 The hydrated pro- 

 toxide ia thrown 

 down as an apple- 

 green powder, when 

 to any of the salts 

 of nickel caustic 

 potash is added. 

 Ammonia has the 

 same effect, but 

 when added in ex- 

 cess dissolves the 

 precipitate, render- 

 ing the solution blue. 

 With sulphuretted 

 hydrogen nickel be- 

 haves as cobalt. A 

 bead of borax, 

 touched with nickel, 

 becomes a reddish- 

 yellow glass, which 

 pales as it cools. 

 In the reducing 

 flame, greyish par 

 tides of the reduced 

 metal are dissemi- 

 nated through the 

 bead. Kupf or nickel, 



the ore from which nickel is usually obtained, is found prin- 

 cipally in Saxony, and, in small quantities, in Cornwall. 



MANGANESE. 



SYMBOL, Mn COMBINING WEIGHT, 55 SPECIFIC GRAVITY, 8*0. 



The metal itself is reduced from its oxide by charcoal at a 

 very high temperature. It is of a greyish colour, feebly mag- 

 netic, hard enough to scratch steel. It soon crumbles to a 

 brown powder in the air, and has the power to decompose water 

 at ordinary temperatures ; hence it has no commercial value, 

 save that it is useful as an alloy with iron. A small per-centage 

 of manganese renders that metal both harder and more elastic. 



Matiganous Oxide (MnO). By heating the carbonate, the 

 carbonic acid gas is driven off, and this oxide remains as a green 

 powder. It is a very powerful base, and rapidly combines with 

 oxygen, forming a brown powder. It makes with mineral acids 

 well-marked salts, which give pink solutions, from which an 

 alkali will throw it down again, as a white hydrate, which be- 

 comes brown on exposure to the air. 



The Sesquioxide (Mn t O s ) has been noticed as capable of form- 

 ing an alum. It appears in nature as braunite. Its salts are 



