MM. Cahours and Cloez, to whom a small quantity of this substance was sent, arrived at similar results to those given above.

When a solution of acetate of lead rendered slightly ammoniacal is added to a solution of sorbine in excess, no lead remains in the liquor, and a precipitate is formed which is first white, but which becomes slightly yellow as it is washed and dried. This precipitate when heated to 212° Fahr., exhales a slight odour of caramel, but the change which it undergoes at this temperature is very trifling. The analysis of this combination gave numbers varying between 73.63 and 75.39, the mean being 74.5 of oxide of lead in 100. The formula 4 Pb O, C12 H, O, is that which corresponds best with the results obtained. This would represent 74.4 per cent. of oxide of lead. The analysis of the lead salt gave 11.2 per cent. of carbon, and 1.48 of hydrogen; while theory requires 12.1 of carbon, and 1.5 of hydrogen.

It would appear from these results, that the formula for sorbine is C12 H, O,+3 HO, or C12 H12 O12, and that its combination with oxide of lead is represented by the formula (4 Pb O, C12 H9 09).

Sorbine combines with chloride of sodium, and this compound forms crystals, which viewed by the microscope appear cubical. The author for the present merely announces the existence of this compound.

Sorbine is colourless, having a decidedly saccharine taste, which cannot be distinguished from that of cane-sugar. The crystals are perfectly transparent, hard breaking between the teeth like sugar-candy. The specific gravity of the crystals is 1.654. Water dissolves about twice its weight of it. Boiling alcohol, on the other hand, dissolves but a very small quantity, which is deposited again on cooling, in the form of octahedrons similar to those deposited from an aqueous solution.

A concentrated solution of sorbine resembles a syrup of common sugar. Its density, determined with a solution which was not quite pure, was 1.372 at 60° F. The sorbine, and the syrup which it forms with water, are therefore both a little more dense than cane-sugar and its solution.

Sorbine dissolved in water and left in contact with beer yeast, gave no indication of fermentation, even after standing for forty-eight hours at a temperature ranging from 68° to 86° F. Diluted sulphuric acid produced no alteration in it, and did not render it fermentable. Concentrated sulphuric acid attacked it quickly, giving it a reddish-yellow colour, and under the influence of a slight elevation of temperature it was converted into a black substance having a carbonaceous appearance, which has not yet been examined.

Nitric acid, either concentrated or diluted with half its weight of water, when added to sorbine and heated, disengages a great abundance of red vapours. The action, which is very energetic, continues spontaneously for a long time. Oxalic acid is obtained as the product of this action. Sorbine furnishes, like cane-sugar, more than half its weight of oxalic acid, which is deposited in large colourless crystals. It was not determined whether, in this reaction, an intermediate substance was formed before the production of the oxalic acid.

Solution of sorbine heated with the alkalies acquires a deep yellow colour, and exhales an odour of caramel. Baryta comports itself with sorbine, just as lime does. Even oxide of lead dissolves with heat in sorbine, with which it forms a yellow solution having a burnt flavour. Sorbine dissolves oxide of copper, forming a blue solution of great intensity, from which suboxide of copper is gradually deposited. Tartrate of copper and potash is also reduced, either with or without heat, by sorbine. Heated on platinum foil, or thrown on to an ignited coal, sorbine comports itself like common sugar, with which it might be confounded; like the latter, it melts, assumes a yellow colour, gives off a strong smell of caramel, and leaves a voluminous carbonaceous residue.

When heat is carefully applied, sorbine emits the vapour of water, which is slightly acid, and is changed to an acid of a deep red colour, the preparation and properties of which will be now described. Sorbine, kept for some time at a temperature varying from 302° to 356° Fahr., leaves a residue of a deep red colour, which consists principally of this new acid. This residue is to be dissolved in potash or ammonia, the solution filtered, and supersaturated with diluted hydrochloric acid. An abundant precipitate of a dark red flocculent matter is thus obtained, which is to be washed with distilled water until chloride of potassium or ammonium ceases to be removed. The precipitate is then dried at from 240° to 300° Fahr., in a stove. This constitutes the new acid, which the author proposes to call sorbinic acid. It is amorphous, of a deep red colour, insoluble in water, in spirit, and in weak acids,

bu very soluble in potash, soda, or ammonia, with which it forms solutions of a rich sepia colour. A trace of sorbine is sufficient to communicate a sensible colour to a large quantity of alkaline water.

The soluble salts of lime, baryta, alumina, iron, tin, gold, and platinum, form, with a soluble sorbinate, voluminous precipitates of a reddish-yellow colour more or less intense. Sulphate of copper yields a yellowish-green precipitate, which is soluble in ammonia, forming a deep green coloured solution.

The analysis of sorbinic acid gave the following results :

Ascribing to the acid the formula C32 H18 O18, the salt of lead would be represented by the formula

(3 Pb O, C32 H18 018).

Sorbine crystallizes in octahedrons which belong to the right prismatic system. M. Berthelot, to whom the author submitted a specimen with the view of having it examined in reference to its optical properties, has ascertained that it influences the plane of vibration of a ray of polarized light, turning it to the left, and that it possesses this property to a degree intermediate between that possessed by solution of sugar which has been altered by acids, and the same solution after the crystallizable portion has been separated.-Journal de Pharmacie.

ON THE TRANSFORMATION OF MANNITE INTO SUGAR.

BY M. LHERMITÉ.

THE existence of a slight excess of hydrogen in relation to the oxygen constitutes the essential difference in the elementary composition of mannite as compared with sugar. On considering the affinities which connect these vegetable principles, we might expect, under certain conditions, to find one of them transformed into the other. This transformation does not appear to have been hitherto studied.

Fresh and perfectly pure manna does not undergo alcoholic fermentation, but after a lapse of some time it is liable to a peculiar alteration. It changes from a white, opaque, dry and almost friable substance, to that of a reddish, translucent, and gluey substance. It is then sufficiently hygrometric to dissolve in the water which it derives from the atmosphere; and this solution, with the addition of yeast, soon becomes converted into alcohol and carbonic acid.

The preceding explains the reason why sugar is found in manna. If, under an oxydizing influence, mannite is convertible into sugar, there can be no doubt that it may also be produced by the action of deoxidizing agents on the sugar itself; it is thus that it is formed in the juice of beet-root submitted to viscous fermentation.Comptes Rendus.

ON THE PREPARATION OF PURE BARIUM COMPOUNDS.

BY HENRY WURTZ.

THE preparation of the compounds of barium in a state of absolute purity is a subject which has not generally received much attention from Pharmaceutical Chemists, in consequence of the hitherto limited application of these compounds, except in chemical analysis. The time, however, is undoubtedly close at hand when new developments in the arts will create a demand for pure barium compounds, as well as for very many other products now considered as pertaining exclusively to the laboratory. Indeed, efforts have already been made to introduce the chlorate of

barytes to the notice of pyrotechnists as a means of producing a green fire unequalled in beauty, and the pure carbonate has been for some time in use in England, in the manufacture of superior varieties of plate and flint glass. The precipitated or purified native sulphate is also preferred as a water-colour pigment to white lead, being far more durable than the latter. I may here be permitted to mention a practical application of the carbonate which has occurred to myself. I have found that sulphate of lime is totally precipitated from its solution by mixing therewith an equivalent quantity of the precipitated or finely pulverized natural carbonate of barytes, of course with the formation of sulphate of barytes and carbonate of lime. It is by no means improbable that this property may be made available in removing sulphate of lime from spring or sea-water which is to be used in steam-boilers, thus preventing the formation of the troublesome incrustation which so often occurs, especially when it is considered that the sulphate of barytes which would be formed might easily be reconverted into carbonate and used over again. Again, sulphate of lime might be removed in the same way from the brine in salt-works, thus contributing to the purity of the salt produced.

Recent improvements in chemical analysis have greatly increased the usefulness of barium compounds in the laboratory, especially of the carbonate, to which the late investigations of Professor H. Rose, and of Ebelmen, have given a place in the very first rank among the reagents valuable to the Chemist. Any suggestion, therefore, concerning the preparation of barium compounds in a pure state, cannot be considered as useless.

The sulphate of baryta is the only compound which occurs in sufficient abundance to be an economical source of the other barium compounds, and the enormous though illegitimate use of this substance in the adulteration of white lead, is so far fortunate as to render it an easy matter to obtain it in any required quantity, already in a state of fine powder, which is so desirable in chemical operations.

The sulphate of baryta is always reduced to the state of sulphide of barium, by exposing it to a red heat in intimate admixture with some carbonaceous substance, such as powdered charcoal, rosin, oil, or flour. It is exceedingly difficult, however, if not impossible, to effect in this manner a complete decomposition of the sulphate. Indeed, it is probable that in most cases the quantity of sulphide obtained is not more than half that which is equivalent to the sulphate employed. A modification which promises to be far more economical was proposed by Dr. Wolcott Gibbs. His proposal was to submit the sulphate to the action of a current of common coal gas at a red heat. It is evident that in this way a perfect decomposition may readily be accomplished, especially if the powdered sulphate is stirred during the operation, so as to expose fresh surfaces to the action of the gas.

The mass obtained after the reduction of the sulphate is submitted to the action of boiling water, and a solution obtained, which, according to Professor H. Rose,* contains principally hydrate of baryta and sulphohydrate of sulphide of barium Ba S. HS. formed by the reaction of equal equivalents of water and proto-sulphide of barium. It almost invariably contains also a quantity of lime, probably in the form of sulpho-hydrate of sulphide of calcium, or of hydrate of lime, proceeding from the almost constant concurrence of sulphate of lime with native sulphate of baryta. From the presence of this lime originates the principal difficulty in preparing pure barium compounds from this substance. Thus, when the carbonate is prepared from the solution by precipitation with carbonate of soda, or a current of carbonic acid gas, it is found contaminated with carbonate of lime, which is fatal to its use as a reagent in analysis. Also in examining many specimens of commercial chloride of barium, which is prepared from this solution by the addition of chloro-hydric acid, boiling to separate sulpho-hydric acid gas which is evolved, filtration to separate the sulphur which is precipitated and crystallization, I have always found it to contain a small quantity of chloride of calcium, which I have found it impossible to separate entirely by repeated recrystallizations. It has been proposed to separate the chloride of calcium from chloride of barium by the use of very strong alcohol, in which the latter when anhydrous, is insoluble. This method is rather expensive and troublesome, as it involves the evaporation to dryness of the chloride of barium solution, the reduction of the previously ignited residue to a very fine powder and digestion in strong alcohol. Attempts were made, after some previous experimen

Poggendorff's Annalen, 55,416.

+ Gmelin's Handbuch, 2158

tation, in which it was found that an aqueous solution of oxalate of baryta precipitated chloride of calcium, but not chloride of barium, to separate the lime from a chloride of barium solution by addition of oxalate of baryta, or simply of a little oxalic acid, but it was soon found that oxalate of lime was somewhat soluble in a solution of chloride of barium, so that a solution of oxalate of baryta gave no precipitate in a mixture of solutions of chloride of barium and chloride of calcium. It was found also that the precipitate formed by a little oxalic acid in a lime solution could be re-dissolved by addition of chloride of barium. It may also be mentioned, though irrelevant to the subject, that it was found that oxalate of lime was soluble in solutions of chloride of calcium, of ammonia, and of chloro-hydrate of ammonia. The well-known property of carbonate of baryta, which the recent investigations of Professor H. Rose have rendered so important in the analysis of phosphates, of completely precipitating lime from its solution by a sufficiently long contact therewith, furnishes us, however, with a perfectly easy and cheap method of purifying the chloride of barium solution. In fact, a solution of chloride of barium to which chloride of calcium has been added, having been treated with a little carbonate of baryta, and allowed to stand in contact with it for two days, with occasional agitation, was found on filtration to be free from lime. The only objection to this method is the considerable length of time required; but I must here describe an elegant modification which was communicated to me by Dr. Wolcott Gibbs, and tested by him in his laboratory; that is to add first to the solution of chloride of barium containing lime a little solution of hydrate of baryta, and then to pass through it a current of carbonic acid gas. The precipitate immediately formed contains of course all the lime.

The only impurity which is prevalent in commercial chloride of barium besides lime, is, strangely enough, a trace of lead, which is almost always present, and sometimes in such quantity that the solution is immediately blackened by sulphuric acid. This is, however, very easily removed, either before or after the separation of the lime by the process of Dr. Gibbs, by passing a little sulpho-hydric acid gas into the solution, gently heating for a short time and filtering.

Commercial chloride of barium thus purified is probably the most convenient source of the other compounds of barium when required pure. Thus pure carbonate of baryta may be prepared from it by precipitation with carbonate of ammonia, or with carbonate of soda, which is free from silicia, sulphuric acid, and phosphoric acid.-New York Journal of Pharmacy.

ON A CLASS OF AMMONIACAL COMPOUNDS OF COBALT.

BY FREDERIC CLAUDET.†

WHEN ammonia is added in excess to a solution of protochloride of cobalt mixed with four times its weight of chloride of ammonium, the solution becomes of a dark brown colour without any appearance of a precipitate. In this state the solution rapidly absorbs oxygen from the air; and on frequently agitating a bottle half filled with it, removing the stopper from time to time to renew the air, the absorption is much facilitated, and is complete in the space of three or four days, the colour of the liquid changing at the same time from a dark brown to an intense violet-red. If the air be replaced in this experiment by pure oxygen gas, the oxidation is still more rapid, and may be completed (if the quantity of solution be not too large) without requiring the removal of the stopper. By boiling this oxidized ammoniacal solution, strongly acidified with hydrochloric acid, a heavy crimson powder is deposited. A slight effervescence takes place at the same time, due to the evolution of a certain quantity of oxygen, and the liquid becomes nearly colourless, owing to the precipitation of the whole of the cobalt in the form of a new compound. The liquid when cold is drawn off from the red powder, which is washed several times by decantation with distilled water, thrown on a filter, and allowed to dry in a warm chamber. The precipitated powder thus obtained is nearly pure. Before examination it is, however, necessary that it should be crystallized. The powder for this purpose is

It may be that leaden pans are used for the evaporation or crystallization of the commercial chloride of barium, which would sufficiently account for the presence of lead in the product. + Phil. Mag. [4] II., 253.

dissolved in boiling water, to which a few drops of hydrochloric acid have been added; and on cooling, the salt is deposited in the form of regular octohedrons, small, sparkling, and of a ruby-red colour, very much resembling small crystals of chrome-alum.

This salt, which is an intense colouring matter, is sparingly soluble in cold water, one part requiring at 60° Fahr. 244 parts of water; it is soluble to a much larger extent in water at the boiling-point, to which it imparts a very deep red colour; it is, however, slightly decomposed, and altogether so on boiling the solution; but this may be prevented by keeping the solution slightly acid with hydrochloric acid.

Hydrochloric acid, and saturated solutions of chloride of ammonium and sodium, completely precipitate the new salt from its solution; alcohol acts in the same way. The salt is not decomposed by boiling hydrochloric acid. Sulphuric acid evolves hydrochloric acid, a corresponding sulphuric salt being formed; the reaction, however, is not complete, for at the end of the operation chlorine comes off from some decomposition. Nitric acid partially transforms the salt into the nitrate of the base. Potash and soda decompose the solution of the salt, a hydrated peroxide of cobalt being thrown down and ammonia evolved in considerable quantity. Hydrate of baryta decomposes the salt in the same way with the aid of heat, but not in the cold. Carbonate of potash or soda has no effect. Yellow prussiate of potash gives with a solution of the salt a dirty brown precipitate, red prussiate none; but on standing, bright yellow needles crystallize from the solution.

Sulphuretted hydrogen precipitates the whole of the cobalt as a bisulphide of that metal, ammonia being liberated at the same time. The analysis of three different preparations of this sulphide gave

Calculated.

Found.

On boiling a solution of the new salt, it is decomposed into ammonia, which escapes, and a superior hydrated oxide of cobalt, containing a certain amount of a nitride of cobalt which is precipitated, nothing but chloride of ammonium remaining in solution. The composition of the precipitated oxide of cobalt appears to be CO3 04+3HO.

Dried in the air, the salt contains no water of crystallization, neither does it contain oxygen. When heated to low redness in a glass tube, a large quantity of ammonia is disengaged, a certain quantity of chloride of ammonium sublimed, and a residue of common protochloride of cobalt remains. In this reaction, no moisture is produced, which would necessarily be formed if any oxygen existed in the compound.

The analysis of this salt was effected in the following manner:-The chlorine was estimated from the chloride of silver, obtained on boiling the solution with an excess of nitrate of silver and nitric acid. In the cold, the precipitation by nitrate of silver is not complete. The cobalt was determined by reducing a certain quantity of the substance introduced into a tube with a bulb, by pure hydrogen and heat. The nitrogen was estimated as ammonia, by distilling the salt with caustic soda, receiving the ammonia into hydrochloric acid, and determining the weight of the double chloride of platinum ammonium. The ammonia was also obtained by heating the salt with soda-lime, according to the method of Will and Varrentrapp. This last process, however, gave less accurate results, a deficiency of about one per cent. in the nitrogen being found. The hydrogen was determined by combustion of the salt with a mixture of oxide of copper and chromate of lead, and copper turnings. The number of equivalents of chlorine, cobalt, nitrogen, and hydrogen thus determined, are 3C1, 2Co, 5N and 16H: