in chemistry and mineralogy, a substance clasped among the semifetals, though several eminent chemists are of opinion that it is a compound; and Mr Bergman, who has made more experiments upon it than any other person, conjectures that it is a modification of iron.

It was first obtained from an ore called kupfer-nickel, fomet.mes. sometimes grey coloured, but often of a reddish-yellow; though several others are now discovered. "It had its name (says Mr Bergman), and probably still retains it, from this circumstance, that though it has the appearance of containing copper, not the smallest particle of that metal can be extracted from it, even by fire." It was first mentioned by V. Hiema, in 1764, in a book written in the Swedish language, concerning the discovery of ores and other mineral substances. It is supposed by Henckel to be a species of cobalt, or arsenic alloyed with copper. Cramer classifies it with the arsenical or cuprous ores; though both they and all other chemists confess that they were never able to extract one particle of copper from it. Mr Cronstedt, in the years 1751 and 1754, showed by many accurate experiments that it contained a new semimetal, or at least that a regulus different from all others was obtainable from its ore. This ore, called kupfer-nickel, or false copper, as has already been observed, is of a coppery lead colour, and almost always covered with a greenish-grey efflorescence. "It is (says Mr Fourcroy) very common at Freyberg in Saxony, where it is often mixed with the grey ore of cobalt; but it is distinguished from it by its red colour." Mr Bergman, however, complains greatly of the scarcity of this mineral, so that he could hardly procure a quantity sufficient to make experiments upon. Fourcroy also tells us, that "Mr Sage, having treated this ore with sal-ammoniac, obtained iron, copper, and cobalt, and thinks that it is composed of these three metallic matters, together with arsenic. It likewise contains a small proportion of gold, according to this chemist. It is proper to observe, that these results do not agree with those of Mr Bergman; he is said to have operated on the kupfer-nickel of Biber, in Hesse, and of Allemont in Dauphiny. Mr Bergman himself, however, informs us, that he undertook his experiments expressly with a view to discover whether the theory of Mr Sage was just; and that he operated mostly on some regulus made by Mr Cronstedt, and found in the Swabian collection.

"Cronstedt (says Mr Fourcroy) assures us, that the metallic matter, called scheiss by the Germans, which is collected in the crucibles used in the melting of smalt, affords nickel. Mr Monnet thinks, that the specks of the manufacture of Gengenbach, 14 leagues from Straßburg, is true nickel; and as the ore of cobalt made use of in that place to make smalt is very pure, he concludes, that nickel is necessarily a product of cobalt itself. But Mr Beaume has obtained nickel from almost all the ores of cobalt by means of sulphur; it therefore seems, that the ore of cobalt, which is wrought at Gengenbach, contains nickel not distinguishable by the eye, on account of the intimate union of these two metallic matters."

"To obtain the regulus of nickel (says Mr Bergman), the ore must be first subjected to roasting; during which a quantity of sulphur and arsenic, greater or less according to the nature of the ore, is expelled; so that it sometimes loses about half its weight, but frequently not above c.3. This ore, though long and completely calcined, does not always acquire the same colour, but in general becomes greener in proportion as it is more rich. Sometimes (especially if suffered to lie at rest) its upper surface is covered with green vegetations, somewhat of the form of coral, which are hard and sonorous. A double or triple quantity of black flux is to be added to the roasted powder, and the mixture well fused in a forge in an open crucible covered with common salt, in the usual method. The vessel being broken, a metallic globule is found at the bottom, the weight of which amounts to 0.1, 0.2, or at the most to 0.5 of the crude ore. The regulus thus obtained, however, is far from being pure; for although the roasting be ever so violent and long continued, yet a considerable quantity of sulphur, but especially arsenic, still remains concealed, exclusive of cobalt, and a great proportion of iron; which last is so generally prevalent, as to make the regulus magnetic: and this variety of heterogeneous matter is the cause why the regulus varies much, not only in respect to its fracture, the polished surface of which is either smooth or lamellated, but also in regard to its white colour, which is more or less yellow or red."

He has not been able to determine the properties of nickel when perfectly pure, as the continual presence of iron in some respect obscures them: From the calculations which he makes, however, Mr Bergman concludes, that the specific gravity of nickel is not less than 9.000 at the least. If a small portion of gold enter the composition, the greatness of the weight might thence be explained; but though this metal is almost always absent, yet 36 parts of it, 48 of iron, and one of copper, were formed by fusion into a globule, the specific gravity of which was 8.8571, but was little soluble in nitric acid; yet after lying about two hours in the acid, the gold was plainly to be seen, and with volatile alkali the menstruum yielded nothing but a ferruginous brown precipitate, which in the fire put on the appearance of calcined iron.

The solutions of nickel in all the acids are green. The vitriolic scarcely attacks the regulus unless by evaporation to dryness. The nitrous acid, by the affluence of heat, dissolves both the calx and the regulus; as does likewise the marine acid, but slowly, and not without the affluence of heat. Acid of arsenic unites with the calx into a green saline mass; but with the regulus it separates a saline powder difficult of fusion. Fluor acid dissolves the calx with difficulty, and forms crystals of a dilute green colour. Acid of borax scarcely dissolves nickel directly, but takes it up by a double elective attraction. Vinegar forms with the calx spathose crystals of an intense green colour, which can scarcely be decomposed by acid of tartar. The faccharine acid converts both regulus and calx into a white powder, not easily soluble in water. Acid of phosphorus attracts it but little. The acid of ants, by decoction or long digestion, attacks the newly precipitated calx; for the solution is green, and upon evaporation yields crystals of a deep green colour, hemispherical, formed of filaments diverging from a centre, and pellucid. They are not soluble in spirit of wine, and scarcely in water, unless it be acidulated. Lemon-juice seems not to act at all upon nickel. All the acids are deeply tinged by dissolving nickel; and this property belongs to the first regulus as well as that which is most highly depurated. Volatile alkali dissolves it, and the solution is of a blue colour; the fixed alkali dissolves it very sparingly, and forms a yellow solution. Nickel becomes the more difficult of fusion, in proportion to its purity, so that at last it requires nearly as great a heat for this purpose as malleable iron. It is easily melted with other metals, but its great scarcity has prevented this matter from being thoroughly investigated. It may, however, be observed, that the impure regulus cannot be united with silver, which must be attributed to the cobalt it contains; for when well freed from that metal, it easily unites in equal proportions with silver, and that without any remarkable diminution of the whiteness or ductility of the latter. This mixture, fused with borax, tinges it of an hyacinthine colour. Copper unites more slowly with depurated nickel, yielding a red and ductile metallic mass, which tinges borax of a reddish hyacinthine colour. It produces only a brittle mass with tin; in which respect it differs from cobalt. It could not be amalgamated with mercury by trituration.

Nickel, when well depurated, does not easily part with its phlogiston, or, in the language of the new nomenclature, receive an accession of Carbonic; for it only assumes a brown colour, and that with great difficulty in the ordinary way of calcination in the assay furnace. By means of nitre, however, it is more completely dephlogisticated, and becomes green. The metallic calx, vitrified with borax, produces an hyacinthine tinge; which yet, if occasioned by a regulus not well depurated, vanishes on continuing the fire, a slight blue tinge being produced by the addition of nitre; but a calx of well depurated regulus of nickel forms a permanent colour. The calx of nickel communicates also an hyacinthine colour to microcosmic salt; which, by long-continued fusion on charcoal, may indeed be weakened, but can hardly be quite discharged. On the addition of nitre it changes to a violet, but becomes again hyacinthine on augmenting the quantity of microcosmic salt. If the calx of nickel be added to saturation, the fused glass assumes a blood-colour; but on being fused, becomes more and more yellow.

Under the article Chemistry, no. 1316, and in the present article, we have observed, that Mr Bergman conjectures nickel to be only a modification of iron. He examines, however, with great care, the opinion of other authors, who suppose it to be composed of arsenic, copper, cobalt, and iron.—"With respect to arsenic (says he) we may very safely exclude it from the number; as experiments show that it may be entirely expelled. It cannot be doubted but that copper is present in some ores of nickel, and therefore may easily be mixed with the regulus; but the greater number are entirely without it. It is true, that nickel is totally soluble in volatile alkali, and that this solution is of a blue colour; but if this argument held good, there would be nothing found here but copper; in which case very different phenomena would take place from those which are produced by nickel. The blue colour, produced both by copper and nickel, can no more prove their identity than the yellow colour produced both by gold and iron, when dissolved in aqua regia, can prove the identity of these two metals. Nickel and copper agree also in this property, that they are both precipitated from acids and from volatile alkali by iron; but a considerable difference appears in the manner in which this precipitation is accomplished. When a polished piece of iron is put into a solution of nickel, a yellow pellicle of the latter will by degrees adhere to it; but this soon disappears on touching, and grows black, unless the acid be well saturated, or sufficiently diluted with water. A similar precipitation is observed if zinc be made use of instead of iron; but in solution of copper so much diluted, that the precipitation on iron may be nearly similar to that of nickel, zinc is immediately covered with a crust of the colour of mountain brass."

An invincible argument that cobalt is no essential ingredient in nickel is, that a solution of the latter in hepatic sulphuris is precipitated by the former. In the same way nickel tinging borax, or the microcosmic salt, in the dry way, is thrown down by the addition of a proper quantity of copper; but this is not the case with cobalt. A remarkable difference likewise occurs with all the acids. 1. Cobalt tinges all these menstrua of a red colour, yielding crystals either of a yellow or bluish red. But nickel produces solutions and concretions of a fine green: it sometimes happens, indeed, that the red solutions yield greenish crystals; but this is to be attributed to nickel in small proportion mixed with the cobalt. 2. Cobalt united with the marine acid yields sympathetic ink, but depurated nickel does not. 3. Cobalt, dissolved in volatile alkali, affords a red solution, but nickel dissolved in the same alkali is blue. 4. Cobalt does not, like nickel, separate, on the addition of arsenic acid, a powder difficult of solution. Iron therefore only remains; and indeed, says Mr Bergman, there are many and weighty reasons, which induce us to think that nickel, cobalt, and manganese, are perhaps to be considered in no other light than modifications of iron.

1. Unequal portions of phlogiston, united to the same iron, or, according to the new nomenclature, iron containing different proportions of carbons, changes its qualities in a remarkable manner: for instance, how very much do the different kinds of iron and steel differ? It is then to be observed, that nickel, cobalt, and manganese, whatever operations they may be subjected to, are so far from being deprived of iron, that, on the contrary, they thereby become more ductile, magnetic, and refractory. Again, the various colours which nickel, cobalt, and manganese exhibit, both by solution and by fire, are also exhibited by iron. Cobalt and manganese occasion a red colour in acids, and the latter in glaas; nickel and manganese occasion an hyacinthine colour when fused with borax; a green is produced in acids by nickel, as also by its calx, and by manganese when long and strongly calcined; and it often leaves behind a scoria of the same colour, if the reduction be performed with a saline flux. Lastly, Cobalt occasions a blue or rather violet colour in glaas; and the same is true of manganese dissolved in fixed, and of nickel in volatile, alkali. Iron exhibits all these varieties; for the acids form with this metal solutions of a green colour as long as it contains a certain quantity of phlogiston; but in proportion to the diminution of this principle, a yellow, red, or brownish red colour is produced. It tinges glaas in the same manner, green, yellow, black, or red. Exposed to the fire for many hours together with nitre, blue, greenish blue, or greenish purple flowers, indeed are transmitted through the crucible; but an efflorescence of the same kind is produced by nitre alone, which, by long continued fire, penetrates the vessels, and is decomposed by the contact of the burning fuel, the alkaline efflorescence. reflections being made blue by the manganese, which is always present in the circumjacent ashes; and these verge more to a green in proportion as the crocus martis is more copious; besides, iron itself is often found mixed with manganese. Hence therefore it appears, that the blue flowers which are expelled from nickel by means of nitre are the produce of manganese, as these impart to glass nothing of the cobalt colour; besides, in the mineral kingdom, we find the nephritic stones, and many others of blue, yellow, red, and green colours, all proceeding from iron alone.

The ores already mentioned, from which nickel has been obtained, are as follow:

1. Mr. Rinnan affirms, that it has been found native in a mine of cobalt in Hesse. It is very heavy, and of a liver colour or dark red. When pulverized, and roasted under a muffle, it forms green excrements, and smokes; but its smoke has no particular smell, nor can any sublimate, either sulphurous or arsenical, be caught. It is soluble in acids, and the solution is green, but a polished iron plate discovers no copper.

2. Aerated nickel is found in form of a calx, and is commonly mixed with the calx of iron; in which case it has the name of nickel-ochre. This is green, and is found in form of flowers on kupfer-nickel. It has been found in Sweden, without any visible quantity of nickel in its composition, in clay which contained much silver.

3. Kupfer-nickel is of a reddish yellow bright colour, as has already been mentioned, and its texture is either uniform, granular, or scaly. It is bright when broken, very heavy, and generally covered with a greenish efflorescence. By calcination it loses much of its sulphur, and becomes green, forming fungous ramifications. Mr. Kalpe informed M. Magellan, that nickel was found mineralized with sulphurated iron and copper in a mine near Nefstone in Cornwall. The fine grained and scaly kinds are found in loose cobalt mines in the province of Helsingeland in Sweden, where they are of a lighter colour than in other countries, and have often been confounded with the liver-coloured marcasite.

4. Nickel mineralized with the acid of vitriol is of a beautiful green colour, and may be extracted from the nickel-ochre, or green efflorescences of kupfer-nickel already mentioned.

To the properties of nickel already mentioned, we may add that of its being constantly attracted by the magnet, and that not at all in proportion to the quantity of iron it contains; for the more it is purified from this metal, the more magnetic it becomes; and even acquires what iron does not, viz. the properties of a true loadstone.