hydrogen of the muriatic acid in the sal-ammoniac; but that the water, formed by the action of this acid and the lime at a low temperature, may afterwards react upon the mixture of sulphur and sulphuret of calcium, producing sulphate of lime and sulphuretted hydrogen. It follows, also, that the muriate may be replaced by other ammoniacal salts, provided that they are hydrated, or that water is purposely caused to be present.-Ann. de Chim. xl., 302.

9. Bromide of Carbon, &c.-Some time since M. Serullas described certain new hydriodides of carbon*. These M. Mitscherlich has shewn to be true iodides of carbont; which result is confirmed by M. Serullas, who has since then, also, published an account of a bromide of carbon which he had previously supposed to be a hydrobromide. This bromide very much resembles the protiodide of carbon. They are both heavier than water-have the same appearance at first under its surface; the same etherial and penetrating odour and sweet taste are both liquid, and both become colourless by washing with a solution of potash, for the purpose of removing impurities.

To form this substance, two parts of bromine are to be added to one part of periodide of carbon; just enough of solution of alkali is to be added to make the iodine set free, disappear; the liquid bromide of carbon, which will appear at the bottom of the solution, is to be separated by a funnel, or otherwise (but without washing with water), and allowed to stand until it has become quite clear: during this time a quantity of iodate of potash, in crystals, will rise to the surface the clear fluid beneath is to be withdrawn, and put into a weak solution of potash, for the purpose of decomposing a little protiodide of carbon formed at the same time; a little bromide is also decomposed, but that which remains is soon left in a pure state.

The principal properties of this bromide, and the differences between it and the iodide, are as follows:-The first becomes solid, hard, and crystalline, at 32° F., and remains solid up to 43° F.; the latter remains fluid at the lowest temperatures. The first, heated in a spirit flame, gives red vapours-the latter, violet vapours; neither burnt with flame; but the fluid hydrocarburet of bromine does burn with flame. Neither of the two appears to act upon water, but a little alkali added, causes their decomposition slowly.

The composition of the iodides of carbon is given as follows:

10. Hyposulphuric Acid.-Dr. Heeren prepares hyposulphuric acid, nearly in the manner of Gay Lussac and Welter, by passing a current of sulphurous acid through a mixture of finely-divided perQuarterly Journal, xv. 297.

Quarterly Journal, N. S. iii. 482.

oxide of manganese and water; but afterwards, to separate the sulphuric acid and oxide of manganese in solution, he uses sulphuret of barium, instead of baryta water; because the latter does not completely separate the oxide of manganese. To remove the excess of sulphuret of barium, he passes carbonic acid through, applies heat and filters; the fluid, sufficiently concentrated, yields pure crystals of hyposulphate of baryta. Being decomposed by sulphuric acid, the hyposulphuric acid is obtained pure. To obtain the largest quantity of this acid, the peroxide of manganese should contain no deutoxide; should be in exceedingly fine powder; and the temperature retained as low as possible. Anhydrous liquid sulphurous acid has no action on the peroxide of manganese.

Many of the hyposulphates were prepared by M. Heeren, sometimes directly, sometimes by double decomposition from the hyposulphates of baryta and lime. The following are briefly the characters of some of the salts:

Potash-fine crystals; anhydrous; bitter; unchanged in air; insoluble in alcohol; soluble in 1.58 of boiling water, and in 26.5 of water at 60°.

Soda-large quadrangular prisms; bitter; unchanged in air; contains 15.54 per cent. of water; soluble in 1.1 water at 212° Fahr., in 2.1 of water at 60°.

Ammonia-difficultly crystallizable; cool taste; unaltered in air; dissolves in less than 1 of water; by heat loses water, and is then decomposed; contains 18.44 per cent. of water.

Buryta-two kinds of crystals; 10.78 per cent. water; bitter and astringent; unchanged in air; decrepitates by heat; soluble in 1.1 boiling water, and in 4.04 of water at 64°.

Strontian-large hexagonal tables; 22.10 per cent. of water; bitter; unchanged in air; not so soluble as the last.

Lime-in appearance resembles the last; bitter; 26.24 per cent. of water; dissolves in 0.8 boiling water, and in 2.46 of water at 56° F. Magnesia-hexagonal prisms; unchangeable in air; very bitter; fusible; 37.69 per cent. water; very soluble.

The metallic oxides all form salts with this acid; all the salts, as Gay Lussac has shewn, are soluble in water, and insoluble in alcohol. —Ann. de Chimie, x. 30.

11. Crystallized Hydrated Sulphurous Acid.-M. A. de la Rive, whilst experimenting upon the liquefaction of sulphurous acid by cold, remarked the formation of crystals in several cases, and especially in the first cooled vessel into which the gas had passed, and being induced to examine them, found them to be a hydrate similar in its nature to the well known hydrate of chlorine. The crystals are beautifully white, have an acid, cool, agreeable taste, and occur in thin plates. They remain solid at temperatures near 40° F., but lose part of the sulphurous acid; at a little higher temperature they lose nearly the whole, and become water. Five parts of the crystals gave nearly one part of gas and four parts of pure water, a result which, if

brought into proportionals, will give a composition for these crystals nearly the same as that assigned by Mr. Faraday to the analogous crystals of chlorine. M. de la Rive thinks it probable from analogy that ammonia and sulphuretted hydrogen may be capable of forming similar compounds with water at low temperatures.

When water is frozen by bringing liquid sulphurous acid in contact with it, a quantity of this compound is always formed; and when sulphurous acid is allowed to evaporate in a watchglass, the dew of crystals left at last is a similar substance.-Bib. Univ. xl, 200.

12. On Potassium and Sodium.-M. Serullas remarks, that a piece of potassium put upon a bath of mercury gradually amalgamates, acquiring a rotatory motion due to its action upon the water in the atmosphere which evolves hydrogen. In dry air the amalgamation takes place without motion. But if pieces of sodium be thrown upon mercury, they are again thrown off with a small explosion, accompanied with light and heat. On the other hand, potassium burns on the surface of water, whilst sodium decomposes it, without producing combustion, so that the phenomena produced by the metals with the two fluids are the reverse of each other.

The effects on water are of course due to the superior temperature acquired by the potassium, occasioning inflammation, whilst that obtained by the sodium is not sufficient for the purpose; but if a solution of gum arabic be used, not too dense nor too thin, then the sodium fires, because the fragments, being retained at one point, become sufficiently heated, ignite with a yellow flame, and then move over the surface of the fluid like potassium. If sodium be fixed upon a bad conductor of heat, as wood, then a drop of water will fire it; but if it be placed upon glass or porcelain, then the effect will not take place; the abstraction of heat in these cases, as well as in that where a surface of pure water is used, is too rapid to allow of the sufficient elevation of temperature.-Ann. de Chimie, xl. 327.

13. Separation of Manganese and Iron, by M. Lassaigne.-This process will not serve analytical purposes, but will supply a pure oxide of manganese; it is founded upon the insolubility of the oxalate of manganese, and solubility of oxalate of iron; but when the latter salt is present, a little of the former enters into solution. Peroxide of manganese is to be acted upon by weak muriatic acid to remove carbonates, then mixed with four or five times its weight of oil of vitriol, heated and evaporated to dryness. After this, eight or ten times its weight of water is to be added; this produces a solution of protosulphate of manganese containing iron and also copper: the solution is to be acidulated by sulphuric acid, the copper thrown down by sulphuretted hydrogen, the clear liquor boiled to drive off the excess of sulphuretted hydrogen, and then precipitated by carbonate of soda. The yellow-white mixture of carbonates of manganese and iron is to be well washed, and then digested in a hot solution of oxalic

acid oxalate of manganese in a fine white insoluble powder is formed, from which the soluble oxalate of iron is to be removed by washing. The purified oxalate, being heated in close vessels, gives off a mixture of carbonic oxide and carbonic acid, and a pure greenish grey protoxide of manganese remains.-Ann. de Chimie, xl. 329.

14. Preparation of Protoxide of Chromium, by M. Frick.—This process is intended for large quantities. The mixture of chromate of iron and nitrate of potash is to be heated to redness as usual, the mass to be washed with water, and the solution, which is often green, evaporated very considerably, in an iron pan. Upon cooling, the solution is to be decanted into glass vessels, and the insoluble residue washed and rejected. The clear yellow liquor obtained is to be boiled in an iron vessel, and flowers of sulphur added so long as they occasion a green precipitate; this precipitate is to be well washed, dissolved in dilute sulphuric acid by means of heat, then precipitated by carbonate of soda, and the precipitate washed and dried.-Ann.“ der Physik, 1828.

15. Reduction of Sulphuret of Arsenic.-In testing for arsenic there is often occasion to reduce very small quantities of the sulphuret in such a manner as to develope most effectually and surely the metallic nature of the base. M. Berzelius's process is now well known; the following is M. Liebeg's: the sulphuret formed by the addition of sulphuretted hydrogen to the acid solution, containing arsenic in the usual way, is to be collected, well dried, and put into a small glass' tube, drawn out at the extremity so as not to be larger than a large needle, and then closed; a layer, two or three lines in thickness, of carbonized tartrate of lime is then to be put over it, and the whole heated by the blowpipe; the upper part first and afterwards the lower. The arsenic is reduced, and forms a brilliant film above the charge of materials, even when the quantity of sulphuret is not more than of a grain.—Ann. der Physik, 1828.

16. Rhodium Salts, according to Berzelius.

Chloride of Rhodium and Potassium.

500

17. Braconnot's Indelible Ink, or Dye.-Whilst engaged in experiments on the production of deep brown colours for dyeing, at an economical price, MM. Braconnot and Parisot were led to examine the nature of the products obtained by the calcination of various organic substances with potash. These results were found to vary with the substances used: thus, when matters containing but little azote were employed, only little colour could be fixed upon fabrics, and that easily removable by alkaline solutions; but when such substances as flesh, skin, and horn were employed, more permanent and deeper colours were obtained. Suspecting that this difference might be due in part to the sulphur present in these bodies, sulphur was purposely added, and then a deep chesnut brown dye was procured, more permanent than any other of the kind known in the arts. This immediately led to the preparation of an indelible ink, which was prepared in the following manner:-20 parts of Dantzic potash were dissolved in boiling water, and 10 parts of tanned leather parings, in small pieces, with 5 parts of sublimed sulphur, added; the whole was boiled to dryness in an iron vessel, then heated more strongly with continual agitation, but avoiding ignition, until the whole became soft; then a proper quantity of water was gradually added, and the whole filtered through a cloth. In this way a very dark coloured liquor was procured, which may be preserved for any period in close vessels, and which ought to be retained in well corked vessels, constantly excluded from the air; this presents no difficulty to its use, for a pen full is sufficient to write a couple of quarto pages. It flows much more freely than ordinary ink, does not embarrass the pen with insoluble matter, and resists chemical agents in such a way as to merit the title of indelible ink.

Paper written with it, when subjected to the action of a boiling solution of potash, or strong sulphuric acid, or strong nitric acid, was nearly destroyed, whilst the characters remained unimpaired. Being first immersed in a mixture of chloride of lime and muriatic acid, and then for twenty-four hours in caustic potash solution, which was ultimately boiled to dryness, still the letters were very distinct. Weaker actions than these could of course do no harm, stronger could hardly be devised.

It is presumed that the same preparation will be found very useful in giving chesnut browns, more or less deep in colour, to cotton, hemp, flax, and silk; or to assist other substances in producing colour. Substances tinted by a salt of iron take a deeper tint from this preparation than those not so prepared. It is also proposed to use it upon linen as an indelible ink.-Ann. de Chimie, xl. 221.

18. Test for Vegetable and Animal Matter.-The nitrate of silver is the test which Dr. Davy thinks to be one of the best for detecting the presence of organic matter in solution. A pure solution of this salt is not altered by the sun's rays; but if the minutest quantity of animal or vegetable substance be dissolved in the water, the solution is discoloured; with common distilled water, the discolouration is