N I C

NIC

( 137 )

wlien fufed is rr= 8.279, and when hammered= 8*666. It requires for its fuiion a heat fullyequal to that for the fufion of manganefe. ItIs very difficultly oxydable even at a white heat:it is not only attvaftible by the magnet but iscapable of acquiring magnetic polarity. Someof the reguli of this metal obtained by Bergmanalfo exhibited nearly the fame properties, butfrom the mode of reduction purfued in bothcafes it appears almoft certain that Richter’spure regulus is in fa£t an alloy of this metalwith iron.

Pure nickel k perhaps capable of two Hatesof oxydation : by long expofure to an intenfeheat with accefs of air it is converted to adark brown oxyd which is Hill magnetical: c■on the other hand the colour of all its lalts isgreen and the precipitate thrown down by de-compofing them with alkali is alfo green, henceit may be concluded that the perfect oxyd ofnickel is green, unlefs this colour as in the cafeof the green oxyds of copper be owing to acombination with water. The green oxyd ofnickel by moderate ignition becomes aih-greywith a flight tinge of blue or green, and in thisftate, according to Klaproth 4 , is compofed of66 of metal and 34 of oxygen. By furtherignition it becomes of a blackifh grey, and con-tains, according to Richter, 78 of metal and 22of oxygen. Both the oxyds of nickel by ftrongignition in clofe veflels even without the con-ta£f of any inflammable body are reduced tothe metallic ftate.

Sulphuric acid, efpecially when heated, dif-folves either nickel or its oxyd ; and by evapo-ration to drynefs, in order to drive off the fu-perfluous acid, leaves behind a faline mafs folu-ble in water and from which by evaporationmay be obtained rhomboidal oftokedrons trun-cated at their bafes of fulphat of nickel. Thecolour of this fait is a bright emerald green,which by moderate ignition to drive off thewater of cryftallization becomes of a greenilh

white.

t Nitric acid by the affiftance of heat adds^igorouily on metallic nickel or its oxyds, and°rms with it a grafs green folution from which

pbmined by evaporation rhomboidal cryftals:but ^ ° n ex P°^ ure t0 a i r at firft deliquate,1C ?y * ou g expofure to a warm atmofphere

„ 16 Skater part of their acid and crumblegreenifq white powder.

^ aci( i fcarcely a&s on reguline nickell ™ e ;, its °*yd without difficulty; the-evaporated folution depofits irregular cryftals at* Bergman, Eff. II, p. a43 .

firft deliquefcent and afterwards efflorefeentlike thofe of nitrated nickel.

Solutions of all the preceding Halts are de-compofcd by the alkaline hydrofulphurets, withwhich they form black precipitates; but ful-phuretted hydrogen has no apparent effedf uponthem. Prulliat of potafli throws down a brightfea-green precipitate; of which, according toBergman, 250 parts contain 100 of metallicnickel: thefe proportions however differ ma-terially from thofe given by Klaproth, accordingto whom 100 grains of reguline nickel afterfolution in fulphuric acid give a precipitate byprulliat of potafh, which after being ignited 16as to become entirely attraclible by the magnetweighs 300 grains.

Tincture of galls produces no precipitate oreven turbidnefs.

The mild alkalies occafion a light apple-greenprecipitate of carbonated nickel in the propor-tion according to Bergman, when carbonatedfoda is employed, of 135 parts for every 100 ofregulus: but according to Richter, when car-bonated potafti is employed, of 292 parts forevery 100.

The cauftic fixed alkalies alfo afford a pre-cipitate amounting according to Bergman to128 parts for every 100 of regulus.

Bure ammonia when added to faturation toany of the falts of nickel throws down a greenprecipitate which is again diffolved by an excefsof the fame alkali: the folution is now of abeautiful Iky blue colour, and probably containsthe acid, the ammonia, and oxyd of nickel com-bined together into a triple lalt. The ammo-niaco-nitrat of nickel, according to Thenard e ,exhibits the following properties. It depofitsgreen cryftals by evaporation; it is deccm-pofable by fulphuretted hydrogen and the alka-line fulphurets: neither acids nor alkalies efi'ettany change in it at the common temperature,but by ebullition with cauftic potafli the ammo-nia is driven oft', nitre is formed and oxyd ofnickel precipitates. It may alfo be decompofedby firft iaturating the ammonia with an acid andthen adding carbonated foda.

Not only the falts of nickel but the oxydsalfo, and even the regulus, are foluble in am-monia, the colour of the fluid thus produced isa dark purple-blue, like the ammoniuret ofcopper. It is decompofable with precipitationof the metallic oxyd by either of the caufticfixed alkalies, as has been already obferved inthe preceding fedfion.

None of the metals are capable of decom-

TTOL. XI.

Analyte E2', 1. p. 4 £%.

Anr.de Chem.XI.II. p. siS.S