VANADIUM. 



779 



phosphate of barytes or lead, silex, zircon and 

 alumine. While it is still moist, it is to be de- 

 composed by concentrated sulphuric acid : the solu- 

 tion immediately becomes of a deep-red colour; 

 and, after having digested the mixture for half an 

 hour, alcohol is added to it, and it is again digested. 

 Ether is then formed, and the vanadic acid is re- 

 duced to the state of salifiable oxide, the solution 

 of which is blue ; and, when it begins to assume a 

 sirupy consistence, it is mixed, in a platina crucible, 

 with a little fluoric acid, to get rid of the silex ; the 

 evaporation is continued over the naked fire, and 

 the sulphuric acid is at last expelled at a red heat. 

 The residue is impure vanadic acid. It is fused 

 with nitre, added in small portions at a time. The 

 vanadic acid combines with the potash, and expels 

 the nitric acid; and nitre is added, until it is found, 

 that, on cooling a small portion of the mass, it ceases 

 to be red. The mass is afterwards dissolved in 

 water, and, after filtration, the residue is slightly 

 washed. A piece of sal-ammoniac, larger than can 

 be dissolved by it, is to be put into the filtered 

 liquid. As this salt dissolves, a white pulverulent- 

 precipitate is formed, which is vanadate of ammonia, 

 insoluble in a saturated solution of sal-ammoniac. 

 The vanadate of ammonia ought to be washed, first 

 with a solution of sal-ammoniac, and afterwards, to 

 remove the sal-ammoniac, with alcohol of 0-86. It 

 is to be again dissolved in boiling water, mixed 

 with a little ammonia, filtered, and left to crystal- 

 lize. It is from this salt that vanadic acid and oxide 

 are afterwards obtained, by heating it gently in 

 open vessels to procure the former, and in close 

 vessels to prepare the latter. In order to obtain 

 the metal, pieces of vanadic acid, which have been 

 previously fused, are to be mixed with pieces of 

 potassium, of equal bulk, in a porcelain crucible ; 

 the cover is to be well fastened on, and the cruci- 

 ble is to be heated with a spirit lamp. The reduc- 

 tion occurs almost instantaneously, with a kind of 

 detonation. The crucible, when cold, is to be put 

 into water, to dissolve the potash, and the reduced 

 vanadium is to be collected on a filter : it is obtained 

 in the state of a black powder, which shines in the 

 sun, and takes a grayish metallic lustre under the 

 burnisher ; but this is not the true aspect of the 

 rnetal. Vanadium is white ; and, when its surface 

 is polished, it resembles silver considerably, or 

 molybdenum, which, of all metals, it is most like. 

 It is not ductile, and is easily reduced to a powder 

 of an iron-gray colour. It is a good conductor of 

 electricity. The powder of vanadium takes fire at 

 a heat below redness, burns without energy, and 

 leaves a black unfused oxide. Vanadium dissolves 

 readily in nitric acid, and in aqua regia; the solu- 

 tion has a fine blue colour. The sulphuric, muria- 

 tic and fluoric acids do not attack it at all. even 

 when they are concentrated and boiling. It is not 

 oxidized by the alkaline hydrates, and it may be 

 heated with them to redness without undergoing 

 any alteration, if the air be excluded. 



The compounds of vanadium and oxygen are 

 three in number : 1. Suboxide of vanadium. It is 

 obtained by reducing vanadic, by hydrogen gas, at 

 a red heat, or by fusing vanadic acid in a cavity in 

 charcoal. It has not hitherto been combined with 

 other bodies, or with acids or bases. When heated 

 in the air, it takes fire, and burns, leaving an un- 

 fused black residue. It is composed of 89-538 parts 

 of metal, and 10-862 of oxygen. 2. Oxide of vana- 

 dium. It is obtained in a state of purity by mixing 

 9-5 parts of suboxide with 11-5 parts of vanadic 



acid, and heating the mixture to whiteness in an 

 atmosphere of carbonic acid gas. It is not fusible 

 at the temperature at which glass softens. It is 

 insoluble in water ; but if it remains long in it, the 

 water gradually becomes green in consequence ot 

 increased oxidation. It dissolves slowly, but com- 

 pletely, in the acids : the solution is blue, and the 

 oxide acts as a base ; but it combines with bases, 

 and forms salts, which may be called vanadites. It 

 is composed of 81-056 vanadium, and 18-944 oxy- 

 gen 3. Vanadic acid is obtained by exposing 

 vanadate of ammonia to a heat near redness, in an 

 open platina crucible, and stirring it occasionally. 

 The vanadate decomposes, becomes at first black, 

 and afterwards, in proportion as it absorbs atmos- 

 pheric oxygen, of a red-brown colour, which, by 

 cooling, becomes gradually pale, and finishes by 

 turning to a rust colour. It is tasteless and inodo- 

 rous : it reddens the colour of moistened litmus 

 paper. As soon as it is red hot, it fuses. In this 

 state, it sustains a white heat without losing oxy- 

 gen, if kept from contact with combustible bodies. 

 When fused, it crystallizes on cooling, and then 

 exhibits a phenomenon which merits observation. 

 It solidifies at a heat which is invisible in day-light ; 

 but the moment that solidification commences, a 

 luminous circle extends from the periphery to the 

 centre, where, owing to latent heat, becoming free, 

 the mass remains red hot as long as the crystalliza- 

 tion continues. The acid contracts much on soli- 

 difying, and is readily detached from the crucible : 

 it is then of a yellowish-red colour, and formed en- 

 tirely of a mass of interlaced crystals. It is not a 

 conductor of electricity. It is slightly soluble in 

 water, to which it imparts a bright yellow colour. 

 One thousand parts of boiling water scarcely dis- 

 solve one part of acid. The acid is deposited, on 

 evaporation, in the form of red concentric rings. It 

 is easily reduced to the state of an oxide, especially 

 under the influence of an acid. Fused on charcoal 

 by the blow-pipe, it leaves a coherent mass, of the 

 colour of plumbago, which is the suboxide : with 

 the phosphate of ammonia and soda, it gives a fine 

 green colour to glass, which appears brown while 

 it is hot : with borax, it also gives a green glass. 

 In this reaction, vanadium resembles chromium ; 

 but the green colour, produced by the former, may 

 be changed to yellow by the oxidating flame, which 

 does not happen with chromium. With carbonate 

 of soda, it is not reduced to the metallic state. It 

 is composed of 74-044 vanadium and 25-955 oxygen. 

 The affinity of vanadium for sulphur is but weak at 

 moderately high temperatures ; nevertheless, there 

 are several modes of obtaining sulphurets of vana- 

 dium. Hitherto, only two have been formed. The 

 sulphuret consists of 68-02 vanadium and 31-97 sul- 

 phur. The supersulphuret is composed of 58-647 

 vanadium and 41-353 sulphur. When vanadium is 

 heated to redness in an atmosphere of vapourized 

 phosphorus, they do not combine ; but when phos- 

 phate of vanadium is heated to whiteness in a char- 

 coal crucible, it is reduced, and gives a porous, gray, 

 unfused mass, which may be compressed, and has 

 then the colour and lustre of plumbago. 



Alloys of vanadium. In experiments upon vana- 

 dium, the surface of platina crucibles is often alloyed 

 with vanadium, which does not alter either the 

 colour or the metallic lustre of the platina ; but 

 when it is afterwards heated to redness, the alloyed 

 parts are covered with a layer of fused vanadic acid, 

 which preserves them from further oxidation. 



Salts of vanadium. The salts which contain 



