IN a previous communication I called the attention of the Academy to the phenomena resulting from the contact of metallic copper with air and ammonia. I showed that the solution of copper thus obtained possessed in a high degree the property of dissolving cellulose, silk, and several other organic substances which resist the action of ordinary solvents. This liquid has advantageously taken the place of the ammoniacal hyposulphate of copper, used by M. Schweitzer, of Zurich, to whom is due the discovery of this curious phenomenon. In the paper on this subject, which I read to the Academy at the end of the year 1858, I mentioned the existence in this solution of a salt of copper, produced by an oxygen acid of nitrogen which I thought was nitric acid, resulting from the combustion of ammonia by atmospheric oxygen in presence of copper. I afterwards found that the acid produced is nitrous acid, by saturating with pure nitric acid the sky-blue liquid so rapidly obtained; this gives, by the addition of nitrate of silver, a crystalline precipitate of nitrite of silver.

This production of nitrous acid had, unknown to me, been previously proved by M. Schönbein, who at the time published in the German journals a paper in which he shows that by passing ammonia over spongy platinum, nitrite of ammonia is produced. M. Schönbein shows that the same salt is produced in presence of copper. Copper," he says, "at ordinary temperatures exposed to ammonia, fixes oxygen, and forms nitrite of ammonia. If fifty grammes of finely divided copper are introduced into a flask filled with oxygen, or atmospheric air, the mass becomes heated, white vapours are given off, which are nothing else than nitrite of ammonia; for a strip of starch paper with iodide of potassium, and previously acidulated, plunged into the flask, will immediately turn blue. . . . The blue solution of copper produced, contains not only oxide of copper, but nitrite of ammonia." M. Schönbein has not separated from this solution the product, the formation of which he has pointed out. The knowledge of his labours has not deterred me from pursuing the more complete study of these curious phenomena of oxidation-a study I had before begun. The process which I have found to succeed best for obtaining large quantities of the ammoniacal solution of copper, which is, so to speak, the raw material necessary for this research, consists in introducing into large flasks, of from 12 to 15 litres capacity, from 15 to 20 grammes of copper, and from 60 to 80 cubic centimètres of concentrated ammonia. The metal proceeding from the reduction of a salt of copper by iron or zinc, is thrown against the damp sides of the vessel, to which it adheres

under the form of a thin layer. In a few minutes the flask becomes heated, and filled with thick white fumes, which being condensed on a cold wet body, give all the characteristics of nitrite of ammonia. When the reaction seems finished, change, by the aid of a bellows, the atmosphere of the flask, which will then contain nothing but nitrogen; repeat this several times at intervals, taking care to renew equally the points of contact of the metal and the products of its oxidation, with the ammoniacal liquid and the air. Invert and drain the flasks, and wash them out several times with liquid ammonia. Independently of the blue solution obtained, there remains in the water and in the ammonia an insoluble product of a variable colour, being sometimes olive-green, sometimes brown or yellow. It is a mixture of the two oxides of copper and of unattacked metal. The blue liquid contains only a fourth or fifth part of the copper employed.

The presence of an ammoniacal salt singularly acce lerates this reaction. By using liquid ammonia, previously saturated with sal-ammoniac, the whole of the copper will be attacked in a few instances, provided there is an adequate quantity of atmospheric air present. The metal then will be completely dissolved, doubtless owing to the tendency of salts of copper to combine with ammoniacal salts.

By evaporating in vacuo, at a carefully managed, or even at a cold temperature, blue solution obtained with copper, air, and ammonia (without adding an ammoniacal salt, which would complicate the already difficult process of separating the products), a non-homogeneous product is obtained, parti-coloured with violet, green, and blue. Cold water separates from it nitrite of ammonia almost free from copper; but this salt cannot be obtained in the isolated state, its solution yielding water and nitrogen in proportion as it concentrates.

The blue solution, when boiled, yields black oxide of copper and nitrite of ammonia; that obtained by the aid of sal-ammoniac, furnishes a green crystalline residue of oxichloride of copper.

Ordinary solvents will not effect the separation from the residue (left by evaporation conducted at a carefully managed or even cold temperature) of the products which it contains. Having long sought for processes suitable to effect this separation, I have obtained very precise results, by employing as a solvent alcohol, previously saturated with ammoniacal gas. In the same way I have obtained, in a crystallized state, the salt, which is the principal product of the reaction. The properties of this new body illustrate perfectly the production and the nature of the complex residue furnished by the blue solution when concentrated or when submitted to rapid or spontaneous evaporation.

To obtain it in large quantities, evaporate to dryness, in a porcelain capsule placed in a water-bath, the blue liquid produced by the simultaneous action of air and ammonia on copper; pulverize the residue, and submit it to the action of boiling ammoniacal alcohol. The

filtered liquid, by cooling, deposits this salt in the form of needle-like prisms of a beautiful violet-blue colour. The mother-water from which it is separated, will serve anew to treat in the same way the residue left by the ammoniacal alcohol, or a fresh quantity of the rough product yielded by the evaporation of the copper solution. The matter which resists the action of this solvent, is the excess of oxide of copper contained in the solution.

The composition of the blue crystallized salt, dried at the ordinary temperature, is represented by the following formula:

NO3.CuO,NHO.HO.

By raising the temperature to 100°, this salt becomes green, gradually losing all the water and ammonia which it contained. To effect this result, the salt must be maintained for several days at 100°. The product which remains is anhydrous nitrite of copper, of the composition

NO3.CuO,

Certain difficulties in the analysis of nitrite of copper and ammonia, long left me in doubt as to its true composition. As this salt when heated decomposes with deflagration, it is impossible to estimate by calcination the oxide of copper which it contains. When the latter body is separated by caustic potash, there is always an excess, however carefully the precipitated oxide of copper may be washed; even when the washings are free from alkali, the oxide itself, after being made red-hot, contains a considerable quantity of it; there is, in fact, a decided alkaline reaction. The only process which I have found successful, is to calcine the salt with quenched and pulverized quartz. It leaves thus 35°2 per cent. of oxide of copper, which is exactly the quantity required by the preceding formula.

A small quantity of nitrite of copper and ammonia, wrapped in paper and placed on a steel anvil, detonates when struck with a hammer.

The salt dissolves in contact with a little water, producing intense cold; by leaving this solution to spontaneous evaporation, a portion of the ammonia frees itself and is disengaged. Nitrite of ammonia and a green crystallized salt are thus obtained, the composition being represented by the following formula :

NO3.3CuO.NH,O.

There are considerable difficulties in the way of the regular production of this salt, furnished by the solution obtained directly from air, ammonia, and copper; for it is itself decomposable in water used in large quantities. Water acts in a remarkable manner on these different products. By pouring a large quantity of it either into the solution obtained directly from copper, ammonia, and air, or on the two products derived from this solution, a beautiful turquoise-blue precipitate is obtained. This body is hydrate of copper, Cu O. HO. By calcination it gives 80 to 815 of black oxide of copper. The formula CuO.HO, requires 81.6 per cent.

This oxide appears identical with that formed by treating a soluble salt of copper by an excess of soda or potash. But all chemists know that hydrate of copper prepared in this way is not stable; it loses its water, and turns black almost immediately, even while being washed in cold water. The blue oxide which I have obtained resists the action of boiling water, and can be heated to 100° without undergoing alteration. It retains, it is true, traces of ammonia, which repeated washings fail to remove. But the quantity of this body is not greater than that of the foreign substances

always found, when searched for, in all the oxides and salts obtained by precipitation; only ammonia is more easily detected, on account of the sensibility of the reagents serving to indicate its presence.

Blue hydrate of copper, which may be ranked as a new and useful acquisition to science and industry, absorbs atmospheric carbonic acid slowly and without changing colour. It is a very finely-divided crystalline precipitate, and its beautiful colour might doubtless be available for painting, and for printing coloured stuffs and paper. If this hydrate could only be produced under the above circumstances, its industrial uses would of course be very limited. But while studying its properties, I have found several methods of preparing it with all the salts of copper soluble in water, particularly with sulphate of copper. In fact, it can be obtained by treating with an alkali a salt of copper dissolved in a quantity of water to which a slight excess of ammonia has been added previously; also by pouring potash or soda into a salt of copper mixed with an ammoniacal ammoniacal solution of nitrate of copper. salt; or by adding a quantity of water to a slightly Thus the expense of preparing this colouring matter is no obstacle. It must not be confounded with the product known as English blue ash," the preparation of which has always been kept secret. The English blue ash is comrather darker, is generally less pure than that of the posed of carbonate of copper, the tint of which, though hydrate of copper.

Concentrated liquid ammonia dissolves from 7 to 8 of which is common to all salts of copper in contact per cent. of this hydrate. This solution, the blue colour with an excess of ammonia, is decidedly the best solvent for cellulose and the other substances more or less soluble in M. Schweitzer's reagent.

One of its advantages is that the dissolved substance can be precipitated without alteration by the addition of an acid; while, by operating under the same circumair and ammonia on copper, the nitrous acid which bestances, with the blue liquid resulting from the action of substances contained in the solution. It is, moreover, comes free, acts more or less energetically on the organic from the presence of this oxide, which is found in the liquid in simple solution in ammonia, that the solution obtained by the direct action of air and ammonia on copper, derives the property of dissolving cellulose; for by placing this substance in contact with nitrite of copper and pure ammonia, dissolved beforehand in a little water, it neither gelatinizes nor disappears, as happens when we employ either an ammoniacal solution of oxide of copper or the liquid furnished by copper under the simultaneous influence of air and ammonia.Comptes Rendus.

Contributions to the History of Oxygen,

by M. C. F. SCHÖNBEIN. Action of Oxygen on Hematoxyline.-The three modifications of oxygen exert an action upon hematoxyline very similar to that which they have upon pyrogallic, gallic, and gallo-tanic acids. Free or combined negative oxygen rapidly colours this substance brownred, then brown, and finally decolorises it, rendering it strongly acid. Oxy-water can remain a considerable time in contact with it without being destroyed, and without colouring it violet. Neutral oxygen does not act upon dry hematoxyline; when this substance is in solution it oxidises it, and the production of oxy-water

potass. Dried over sulphuric acid, these crystals present the composition 2 (KO.CO2), 3 HO; after having been heated to 100° they show a composition expressed by the formula KO.CO, HO. When heated for some hours at 130° to 135°, the water is completely expelled, and their crystalline form destroyed.-Sitzungsberichte de K. Akademie der Wissenschaften zu Wien.

On Tungsten and Some of its Alloys,
by M. F. A. BERNOULLI.

In this work the author proposes to investigate principally the alloys of tungsten with other metals. Having, in the first place attempted to obtain metallic tungsten in the fused state, he did not succeed, although having at his disposal very perfect means of heating.

Tungsten is always obtained in the form of a black powder, having a density of 171 to 173 for the metal reduced with carbon, and 17'9 to 18.2 for the metal reduced by hydrogen.

Upon fusing turnings of gray cast iron with tungstic acid or white cast iron with the addition of carbon, the

author obtained alloys possessing remarkable properties and especially of great hardness. He admits that the carbon present in cast iron in the state of combination does not act upon tungstic acid, and that only the carbon in the state of mixture reduces the tungsten to the metallic state. Indeed, the alloys obtained still contain carbon, and that in a proportion up to 5'18 per cent. Tungstic acid can be replaced in the preparation of these alloys by wolfram or by Scheelite.

With respect to copper, lead, antimony, bismuth, zinc, nickel, and cobalt, the fusion of these metals with tungsten does not yield alloys. Upon reducing a mixture of the oxides, very slightly fusible alloys are obtained. The fusion of tungsten with silver gives either nonhomogeneous ingots or infusible masses; it is the same with gold.

On the Degrees of Oxidation of Tungstic Acid. -It is known that tungstic acid assumes, under some circumstances, a green colour. It has been supposed that this coloration may be due to a partial reduction of the acid. This is not the case; indeed, yellow tungstic acid, heated to red-whiteness in a current of oxygen, becomes green, and assumes, at the same time, a crystalline

texture.

The same transformation takes place when the acid is heated in a crucible in the midst of an oxydising atmosphere; at the same time, a partial sublimation of the acid in the crucible is observed. Upon reducing by hydrogen the yellow and the green acid, it is found that their composition is exactly the same, and that, therefore, they constitute two isomerie modifications of the same oxygenated combination. To these two modifications, of which the author proposes to designate the first by the name of pyro-tungstic acid (b), reserving for the first the name of tungstic acid (c), must be joined a third tungstie acid, the meta-tungstic acid (a) of M. Scheibler, which is perfectly soluble in water.

The experiments of M. Bernouilli lead him to assign to tungsten the equivalent 934, his analyses yielding numbers varying between 9322 and 93'97.

luble tungstates, reduced to fine powder, are fused in a platinum crucible with carbonate of soda. The fused mass is taken up with water; the aqueous solution, filtered to separate the insoluble metallic oxides, is neutralised in the cold with acetic acid. The silica, if there be any, is completely precipitated by a slight excess of acetic acid, and may be separated by filtration.

The solution is treated with acetate of lead, when there is precipitated tungstate of lead, PbO.WO,, easy to wash. This salt is digested with the filter during halfan-hour in sulphide of ammonium, which dissolves the tungstic acid and precipitates the lead in the state of sulphide. The solution is filtered and evaporated to dryness in a platinum capsule, with the addition of nitrio acid, and the residue is calcined and weighed,

If the acid contains niobic acid, it is necessary before completing the evaporation to dryness with nitric acid to take it up with dilute ammonia, which leaves the niobie acid undissolved, Poggendorff's Annalen,

On a New Harmonica Chemica, by Dr. T. L. PHIPSON, F.C.S., &c.

IT is known that protosulphite of iron, Fe O. SO2 + 7HO, contains seven equivalents of water. be driven off at 100° C., but the other one equivalent Six of these can FeO. SO3+ 7HO is taken and heated gently, to drive off only at a much higher temperature. Now, when six equivalents of water, and the white mass then pulverized, and introduced into a short glass tube about four inches long and three-quarters of an inch wide, perfectly dry, and supported by the cork, through which passes a little piece of bent tube, a curious phenomenon is observed when the tube is heated by means of a spirit-lamp. The salt occupying the narrow end of the tube, the lamp must be moved backwards and forwards sound begins to be heard. It is then deposited, and left along the whole length of the tube, until a buzzing of water begins to leave the salt, a low buzzing sound under the dry sulphate, As soon as the last equivalent begins to be audible, and soon increases rapidly in This sound appears to be due to a rapid vibration of the intensity as long as the salt continues to lose any water. tube caused by the evolution of successive molecules of water from the salt; it does not cease until the whole of the water has been expelled; and if then the tube and the experiment may be repeated the next day. I have its contents be allowed to absorb moisture from the air, thus produced this loud humming noise three successive times in the course of four days. When the white sulheated in a capsule, the loss of the last molecule of phate, containing only one equivalent of water, is water takes place with a series of cracking noises; at the same time the substance is more or less projected out of the capsule. Now, in the tube supported by the cork, the substance being finely pulverised, no decrepitation takes place, but a series of vibrations, which produce the humming noise in question.

If, in making this experiment, any water is allowed to condense in the small bent tube, the noise ceases.

Experiments on the Deportment of Carbonate of Lime at a High Temperature, both with Fluxes and alone, by G. ROSE.

1 Monatsberichte der Berliner Akademie, 1869,

1, 1862,

I. On heating a mixture in atomic proportions of the carbonate of soda and potash in a platinum crumble until in perfect fusion, then adding small quantiti of ehloride of calcium, the latter will be completal dissolved without effervescence, If the fused mass is allowed to cool, and a portion of this is placed in water at the ordinary temperature, it will gradually pass into solution, leaving a pulverulent residue of carbonate of lime. An examination of this residue shows it to consist of an aggregate of very small globules; after twenty-four hours-sometimes in less time-these increase in size, and are converted either into beautifully crystallized single rhombohedrons or rhombohedral groups of calcite.

II. If another portion of the mass is thrown into boiling water, boiled for some time, and the residue examined under the microscope, it will be found to consist of small prisms of aragonite, with occasional rhombohedral crystals of calcite, but none of the above mentioned globules; if the residue be allowed to remain under water, the prisms after a time are converted into minute rhombohedrons of caleite. These phenomena are then identical with those obtained when a mixture of the solutions of carbonate of soda and chloride of calcium is made, as long since described by the author in his first article on this subject, (See Pogg. Ann. (1837), xlii. 354.)

III. Instead of adding chloride of calcium to the fused carbonates, powdered calcite, or rhombohedral fragments of calcite, chalk, or aragonite, may be substituted; these dissolve completely, without effervescence in the flux, and give the same results as above-mentioned when the fused mass is treated with hot or cold water. IV. Oxalate of lime at a low red heat, after losing the water it contains, is converted into carbonate of lime with evolution of carbonic oxide; under the microscope the product appears to consist of minute amorphous globules similar to those obtained above, and these remain unchanged when placed in water; even when boiled, the globules still retain their amorphous formthey are not converted into calcite.

117

the same properties as the unignited amorphous chalk. Although somewhat more coherent, the chalk was not materially altered, and in no-wise converted into crystalline calcite,

The experiment repeated with fragments of rhombohedral calc-spar, was also interrupted by the rupture of the gun-barrel. The smaller fragments were converted into caustic lime without change of form, the larger pieces were only superficially altered; notwithstanding the great heat, the inner mass was unchanged, and the limit of the surface crust sharply defined. The same result was obtained by the author under different conditions: Mitscherlich presented him with a mass of limestone from Rüdersdorf, which, on account of its size, had passed through the lime-kiln without being completely burned. It contained a kernel of unburned lime, and, notwithstanding the great heat through which this had passed, it proved on examination to have the same characters as the compact limestone which had not been exposed to the heat of the kiln,

It appears therefore, from these experiments, that chalk or compact limestone cannot be converted into crystalline limestone (or calc-spar) by exposure to a high temperature in closed vessels; and as a general fact, that rhombohedral carbonate of lime is not formed in the dry way. The author further observes, that on comparing accurately the description of Hall's experiments and those afterwards made by Bucholz3, that probably they obtained results similar to those just described, and that the slightly coherent, but otherwise unaltered, mass was erroneously considered to be crystalline marble, Notwithstanding the frequency with which this experiment of Hall's has been quoted, and the use that has been made of it, not only in explaining geological phenomena, but in serving as the foundation of whole theories, it was never repeated or confirmed; and the experiments of the author show how hasty the conclusion was. It is not to be disputed that at the junction with granite and basalt, compact limestone and chalk are often converted into marble, as in Paradiesbacken, near Drammen, in Norway, and near Belfast, in Ireland; but these changes cannot be considered as due to heat alone, they were manifestly assisted by other agencies,a conclusion also arrived at by Bischof, although in a different manner.-Pogg. Ann., cxi, 156.

PHARMACY, TOXICOLOGY, &c.

On the Behaviour of Essential Oils to Iodine and Bromine, by JOHN M. MAISCH.