oxygen with the oxide of ethule, and that the chlorine and oxygen in the whole compound are just sufficient to form chlorohydric acid, water, and carbonic oxide, with the hydrogen and carbon.

The existence of a compound of the oxide of ethule with an acid containing seven atoms of oxygen, led us to attempt to combine, by the same method, this base with nitric acid. For this purpose, we subjected a mixture of sulphovinate and nitrate of barytes to the same treatment as described above, but the reaction, even when conducted with the greatest possible care, is destructive; hyponitrous ether, and gaseous matters, being the principal products obtained. Nor were we more successful in our attempts to procure a sulphurous or hyposulphuric ether by the same process.

Remarks upon an Examination of the Peroxide of Manganese. By HENRY C. LEA.*

It is of great importance, both to the practical and theoretical chemist, to have the combinations which the different metals form with the acids investigated, in order that the proper degree of confidence may be reposed in the various theories which have been formed from time to time by so many celebrated chemists. It is with this view alone that I consider these examinations as worthy of being published, as I unfortunately had not time to pursue them far enough to afford any very definite result. They may however serve to point the way to some one who has sufficient zeal for the science, to carry them out to some more useful end than I could hope to attain. I must here make my acknowledgments to Prof. Booth, in whose laboratory, and with whose assistance, these examinations were made.

To peroxide of manganese has never been investigated, as its existence has until lately been questioned by some of the first chemists in Europe, and the tendency of its salts to convert themselves into proto-salts, contributed to render it problematical whether it was not merely the protoxide disguised. It can be obtained in various ways, but the most convenient is to calcine the proto-nitrate gently until the nitrous acid ceases to be given off. A less troublesome method is to heat the common black or deutoxide, until part of its oxygen is given off, but this method is uncertain, as too great a heat converts it into the manganoso-manganic oxide, and it is almost impossible to obtain the black oxide free from admixture with iron. When obtained by caleining, its color is of a deep black, and sometimes shining; but when precipitated from a liquid, as the permanganate of potassa, it is of a dark brown. It has sometimes been found native, and is then known to mineralogists under the name of Braunite. It unites with water and forms the hydrate, which may be readily produced by precipitating the hydrated protoxide from a

• From Silliman's American Journal.

proto-salt, and exposing it to the action of the atmosphere. Obtained in this manner it appears under the form of a brown powder, but when found native, it is black and crystallizes sometimes in acicular crystals, and sometimes in octahedra, resembling in this state the deutoxide. The peroxide is composed, according to the calculations of Berzelius, of 43.37 of oxygen to 100 of manganese.

With the different acids it has very various actions; with some it is converted into protoxide, forming proto-salts; while with others it immediately forms per-salts, which seem to have no regular colour, some being red, while others are nearly white, brown, or yellowish; a dirty white is however the most usual appearance. I have found it to be the case, that most vegetable acids which convert the peroxide into protoxide by giving off oxygen, when acting upon the deutoxide, will form per-salts by the loss of oxygen. They all contain a very great excess of acid, without the presence of which the peroxide seems incapable of forming any salt. The best test I have met with for distinguishing them from the soluble proto-salts, to which they in appearance bear a great similarity, is the yellow prussiate of potash. With the per-salts it gives a greyish green precipitate, while with the protoxide solutions the precipitate formed is white or whitish pink. The hydrochlorate of platina is also a good test for them, as with them it forms a yellowish precipitate, but with those of the protoxide, it forms none.

Sulphuretted hydrogen.-When this gas is passed over the peroxide placed in a tube, which at the same time is heated, the gas is decomposed, sulphur and water are given off, and the oxide is converted into a sulphuret of a light green colour. The gas must be passed over until the tube becomes cool, for if the sulphuret be exposed to the air while hot, it inflames, acting the part of a pyrophorus. When digested in fuming nitric acid, a violent action takes place, the sulphuret is decomposed and converted into a proto-salt, and all the sulphur is precipitated. Analyzed in this manner it gave 9.6 per cent. of sulphur, and when heated in the open air until the sulphur was burnt out and the oxide converted into manganosomanganic oxide, it yielded 100 per cent. of manganoso-manganic oxide, which contains 72.178 per cent. of metallic manganese. Now 9.6 of sulphur will combine with 16.51 of manganese, which makes 26.11 per cent. of sulphuret. There then remains 55.67 per cent. of manganese, which, if considered as manganoso-manganic oxide, would form an oxy-sulphuret, containing

Sulphuret of manganese.

Manganoso-manganic oxide...........

26.110

71.893

98.003

Thus in the operation, both the oxide and sulphuretted hydrogen are decomposed. The oxide is partly reduced to manganosomanganic oxide, and partly to metallic manganese. The sulphur from the sulphuretted hydrogen is mostly driven off, but some of it

combines with that part of the oxide which has been converted into the metal, while the oxygen from the oxide, and the hydrogen from the gas, unite and pass off under the form of steam. This oxysulphuret very much resembles the substance formed by gently calcining the red sulphuret in a close vessel (during which operation sulphuretted hydrogen is given off), but it upon analysis gave but 92.857 per cent. of manganoso-manganic oxide, while the first forms 100.

Cyanogen. When cyanuret of potassium is added to a solution of a per-salt of manganese, the cyanuret is precipitated under the form of an extremely fine greyish green powder, which remains suspended in the liquid for some time.

Sulphuric acid.-The persulphate may be formed by digesting the black oxide in sulphuric acid for several days in the cold, or when peroxide is placed in dilute acid, it is formed in a few hours, but when the peroxide is used, there is a greater excess of acid. This solution is of a beautiful carmine red, but if the oxide be that precipitated from the permanganate of potassa, the solution has somewhat of a violet tinge. It has so great a tendency to convert itself into protosulphate, that it can neither be evaporated nor crystallized, and it cannot be kept for any time, as it is decomposed in the course of two or three weeks. This change may be accelerated by the addition of alcohol.

Sulphate of Manganese and Potassa.-This salt, which is the manganese-alum, may be formed, according to Mitscherlich, by adding a concentrated solution of sulphate of potassa to one of persulphate of manganese. It crystallizes of a violet brown colour, and is decomposed by the addition of water.

If bisulphate of potassa be digested upon deutoxide of manganese, there is a strong action, which results in the formation of a double salt, which, upon evaporating, remains under the form of a somewhat crystalline mass of a dirty white colour, and a pleasant acid taste; it reddens litmus paper, and shows the reaction of the peroxide with yellow prussiate of potassa, and does not seem to be decomposed by water; but it is most likely the manganese-alum of Mitscherlich.

Nitric acid.-When nitric acid is digested upon peroxide of manganese, it does not form a per-salt, but the nitrate may be made by adding nitrate of lead to the persulphate of manganese, until they are both neutralized.

Hydrohcloric acid.—If this acid be digested upon per or deutoxide of manganese, there is a perchloride formed of a dark brown colour, and which decomposes immediately by the application of heat, or in a week or two, in the cold. There then remains protochloride, while chlorine is evolved. When evaporated to dryness, we obtain crystals of protochloride of a fine pink. Dr. John passed chlorine through a solution of 300 grains of protochloride, dissolved in 12oz. water, cooled to 41°. The liquid gradually congealed as

the operation proceeded, and produced a yellowish crystalline mass, which melted at a temperature a little above 41°. It was decomposed by evaporation. This may only have been the perchloride, surrounded by liquid chlorine, for when I repeated this experiment, at a temperature above 41°, I obtained a yellowish crystalline mass, which, however, on being placed between blotting paper to dry it, proved that a yellow liquid imparted that colour to the salt, which itself was pink. I did not, however, observe that it was decomposed by evaporation.

Sulphurous acid. This acid has no action upon the peroxide, even when passed over it in a heated tube; and with the deutoxide it forms proto-hypo-sulphate. I do not think that the per-sulphite can be formed unless by double decomposition with some other salt.

Carbonic acid.-It has no action upon the peroxide, and, as far as I have observed, it cannot be made to combine with it. The brown substance mentioned by Thomson (Chem. Inor. Bodies, vol. II), and formed by decomposing the persulphate of manganese by carbonate of potassa, is most probably an hydrate of one of the oxides.

Phosphoric acid.-When digested upon peroxide, this acid forms a pink solution, giving the per reaction with tests, and which upon evaporation leaves an uncrystallizable pasty mass, of a pink or violet colour, which becomes colourless in a short time, most probably by decomposition.

Boracic acid. The borate can be readily formed by dissolving the peroxide in boracic acid. The solution thus formed by evaporation leaves a whitish crystalline mass, soluble both in nitric and muriatic acid.

Arsenious acid.-When peroxide is digested in arsenious acid, they unite and form a soluble pinkish white salt.

If bi-arsenite of potassa be digested upon peroxide of manganese, it forms a double salt, being arsenite of manganese and potassa.

Chromic acid.-Chromic acid seems to have no action upon the peroxide, but a chromate may be formed by digesting the peroxalate in chromic acid. The solution is of a dark chesnut brown, but it cannot be evaporated or crystallized, as it is decomposed by the application of heat.

Bichromate of potassa has no action upon the deutoxide of man

ganese.

Oxalic acid. This acid has a violent effect upon the peroxide. Oxygen is given off, the insoluble protoxalate is precipitated, while a soluble peroxalate remains in solution. By careful evaporation it may be crystallized, but it is very apt to be decomposed, forming an insoluble salt, most probably the protoxalate. It dissolves in muriatic and nitric acid. It was analyzed by dissolving and precipitating the oxalic acid by chloride of calcium: while another portion was

• Berzelius, Traité de Chimie, Tom. IV, p, 170.

calcined and converted into manganoso-manganic oxide.

Treated

in this manner it showed 27.4348 per cent. of oxalic acid, and 8.5 of manganoso-manganic oxide = 11.73 of peroxide. This leaves a very large per centage for water of crystallization. Thus :

Oxalic acid,

...

Peroxide of manganese,
Water and loss,

27.4348

11.7300

60.8352

100.0000

The 11.73 of oxide, requires very nearly 16. of oxalic acid; which leaves 11.4348 of free acid, so that this salt, in common with the others, possesses a great excess of acid.

If binoxalate of potassa be digested upon the deutoxide of manganese, in the cold, a pink coloured solution is formed, which by standing becomes yellow, letting fall a pink powder. If the solution of the binoxalate be hot, the action is very violent, and the resulting solution is yellow. By evaporation it leaves a crystalline, almost tasteless mass, partly white and partly green, and which is readily dissolved in water.

Acetic acid.-Glacial acetic acid does not form a per-salt when digested on peroxide of manganese.

Tartaric acid.-If this acid be digested upon peroxide, oxygen is given off and the prototartrate is formed. But if we dissolve deutoxide instead of peroxide, a pertartrate results, which on being evaporated leaves the salt of a light yellow or straw colour.

Bitartrate of potassa, particularly if warm, dissolves the deutoxide of manganese with considerable energy, at the same time evolving oxygen, and forming a tartrate of manganese and potassa, which is a highly crystalline brownish mass, of hardly any flavour, and soluble both in nitric and hydrochloric acids.

Benzoic acid. When benzoic acid is boiled with peroxide of manganese, there is a benzoate formed, slightly soluble in water. Thus obtained, it is a dirty white substance, of a crystalline appearance.

Succinic acid. This acid forms a protosuccinate when digested upon peroxide, but with the deutoxide, it, like tartaric acid, forms a per-salt, which is soluble in water, of a whitish colour, crystalline and very acid.

Racemic acid.-This, like the last, forms a per-salt with the deutoxide, and a proto-salt with the peroxide. The resulting solution, by evaporation, leaves the salt somewhat crystalline, whitish brown, and quite acid.

Citric acid. With citric acid, both the per and deutoxide act as towards the last. The percitrate obtained from the deutoxide is a brown, gummy, seemingly uncrystallizable mass, of a pleasant acid. taste, slightly deliquescent, and is soluble, although not very readily, in both nitric and muriatic acids.

Gallic acid.-The pergallate of manganese may be obtained by dissolving the peroxide in gallic acid. The solution thus obtained