mass with crystals of boron which are readily recognized. This mass consists of aluminium containing crystallized boron. It is treated with soda to dissolve aluminium, by hydrochloric acid to free it from iron, and by nitric and hydrofluoric acid to dissolve traces of silicon left by the soda in the boron. From adherent alumina it can only be separated by mechanical means.

Boron crystallizes in the dimetric system; its fundamental form is a rectangular prism with a square base; and M. Sella, who has measured some crystals, considers it to be completely isomorphous with tin. It appears to occur in three varieties of form, all derivable from the above, according as the proportion of the substances used in its preparation, the temperature employed, and the duration of the action are modified. These circumstances also alter very much the hardness of the boron, although the least hard variety is harder than corundum, and the hardest is almost as hard as diamond. Its colour varies very much, from a deep, almost opake, garnet-red, to an almost colourless honey-yellow; and analysis has shown that under these various conditions its composition varies as its colour. Boron possesses a lustre and refrangibility so great as to be comparable to diamond alone in this respect. Its specific gravity is 2.68, a little higher than that of silicon; and it is remarkable that whilst the density of silicon is equal to that of silicic acid, that of boron is superior to that of boracic acid, and that of carbon is much higher than that of liquid carbonic acid.

The flame of the oxyhydrogen blowpipe does not sensibly fuse crystallized boron. Oxygen acts upon it at the temperature at which diamond burns, but a small layer of boracic acid hinders further oxidation. Chlorine acts upon it with remarkable energy, forming gaseous chloride of boron. All the acids, whether pure or mixed, in the cold or when heated, are entirely without action on boron; and it is oxidized to boracic acid only by bisulphate of potash at a red heat. Concentrated caustic soda does not act upon it, but hydrate of soda and carbonate of soda dissolve it slowly at a red heat. It is the most unattackable by chemical agents of all elements.

The circumstances of its formation exercise considerable influence on its composition, and it has never been obtained quite pure. Carbon has been found to be contained in all the specimens analysed, and aluminium in some of them.

Its analysis was effected by exposing it to a high temperature in a current of chlorine; gaseous chloride of boron is formed, and a residue of carbon is left which is burnt off in a current of oxygen. It is probable that the carbon which is met with in boron is in the state of diamond; for the more its proportion in the boron increased, the more did its transparency also increase.

And instances are not wanting in which a substance in crystallizing carries with it a small quantity of another body whose crystalline form is different from its own.

Heinrich Rose is engaged on a complete investigation of tantalum and its compounds, and has already published* some of his results. He prepared metallic tantalum by a method essentially that of Berzelius, namely, by the action of sodium on the double fluoride of tantalum and sodium. The two substances are placed together in a well-covered crucible and heated; the action commences at a dull red heat, and is so violent that the crucible becomes suddenly incandescent. The mass, on cooling, is washed out, and metallic tantalum is left in the form of a dark black powder. It is, however, not quite pure, but contains some acid tantalate of soda. It conducts electricity very well, although Berzelius found that it scarcely did so at all. It is not attacked by any acids except nitrohydrofluoric, which dissolves it. It is slowly oxidized by bisulphate of potash to tantalic acid. When gently heated in chlorine, it glows and absorbs the gas very rapidly, chloride of tantalum distils off, and there is left a residue of acid tantalate of soda with which the metal is always contaminated.

Tantalum is also obtained by passing phosphorus vapour over heated tantalate of soda; but the metal so obtained is not very pure, and does not conduct electricity.

With a view to determining the atomic weight of tantalum, Rose prepared chloride of tantalum in a state of great purity by methods which have been already described by him. When pure, it is of a light yellow colour; it begins to volatilize at 144° C., long before its melting-point, which is at 221° C., and sublimes completely, condensing into a solid crystalline mass. In contact with water it decomposes into tantalic acid and hydrochloric acid, and its analysis was effected by treating it with water to which ammonia was added, by which means the tantalic acid was more readily and completely precipitated. In the filtrate from it the hydrochloric acid was determined by nitrate of silver.

The mean of a great many analyses executed in this manner gave numbers from which the composition of tantalic acid is deduced to be,-tantalum 81.14 per cent., oxygen 18.86 per cent. This differs somewhat from the numbers obtained by Berzelius. M. Rose shows that his method is defective. Berzelius believed that the composition of tantalic acid was Ta2 03, and that it was to be classed with alumina, oxide of iron, &c. Rose has at various times inclined to consider it as TaO3 and Ta2 05.

* Poggendorff's Annalen, August 30, 1856; October 30, 1856; January 1857.

In the former case it would range in the same class with tungstic acid, with which it has some similarity; in the latter case, in the same class as antimonic acid. But he holds, that on the whole there is a balance of probability in favour of its being considered as TaO2, and hence like stannic and titanic acids. On this view its atomic weight would be 68.82*.

The bromide of tantalum is obtained like the chloride. It is yellowish in colour when free from excess of bromine, in which state, however, it is obtained with extreme difficulty. Iodide of tantalum could not be prepared.

Fluoride of tantalum is obtained by dissolving hydrated tantalic acid in hydrofluoric acid. On heating, the fluoride of tantalum volatilizes. Tantalic acid which has been heated does not dissolve in hydrofluoric acid. Fluoride of tantalum has a great tendency to unite with metallic fluorides to form double salts: with fluoride of potassium it combines in several proportions.

Rose obtained a nitruret of tantalum by exposing chloride of tantalum to the action of ammoniacal gas. This is absorbed at the ordinary temperature, and a solid crust is formed, from which, when heated in ammoniacal gas, tantalum is reduced combined with nitrogen. A black powder is thus obtained, which, when rubbed in the mortar, assumes a metallic lustre. It conducts electricity very well: it burns in the air with incandescence to white tantalic acid. It is only dissolved by nitrohydrofluoric acid; fused with hydrate of potash it gives off ammonia. It has very probably the formula No Ta3.

XLII. Proceedings of Learned Societies.

ROYAL SOCIETY.

[Continued from p. 208.]

June 12, 1856.-The Lord Wrottesley, President, in the Chair. THE following communication was read :

:

"Researches on the Action of Sulphuric Acid upon the Amides and Nitriles, with Remarks on the Conjugate Sulpho-acids." By George B. Buckton, Esq., F.L.S., F.C.S., and A. W. Hofmann, Ph.D., F.R.S.

Since we had the honour of addressing the Royal Society upon the subject of the behaviour of acetamide and acetonitrile towards sulphuric acid, we have completed our experiments upon the amides and nitriles, and extended our researches to other groups of bodies. The results of these additional inquiries we now beg to present in the

In fixing the equivalent of tantalum, it deserves to be mentioned that if we take it at 69, it will be the arithmetical mean between the equivalents of molybdenum and of tungsten, which are respectively (in round numbers) 46+92 46 and 92: thus =69. 2

form of a second short summary, the analytical details and the more extended description of the new compounds being given in the complete memoir, which, at the same time, we have the honour of submitting to the Society.

Before proceeding, however, to give an account of our new compounds, it may be desirable to state that several considerations, suggested by the progress of our inquiry, have induced us finally to adopt the name of Disulphometholic acid instead of the provisional term Tetrasulphomethylic acid under which we have described, in our first communication, the new acid generated by the action of sulphuric acid upon acetamide and acetonitrile.

ETHYLE-SERIES.

Action of Sulphuric Acid upon Propionitrile.

Considerable difficulty is experienced in preparing this nitrile in a state of purity. It was finally obtained by acting upon propionamide with anhydrous phosphoric acid.

When three parts by measure of the nitrile are cautiously mixed with two parts of fuming sulphuric acid, and heat is applied, the liquids enter into a sort of ebullition, carbonic acid being copiously evolved; at the same time a portion of propionic acid passes into the receiver, the amount of which may be lessened by raising the temperature only gradually.

At the close of the operation a tenacious mass is found in the retort, which, when dissolved in water and neutralized with carbonate of barium, furnishes two rather soluble but readily crystallizable salts, very difficult to separate one from the other. Their isolation may be conveniently effected, by converting them into the corresponding ammoniacal compounds, by precipitating their solution with carbonate of ammonium.

The filtrate yields two substances, one of which crystallizes, while the other is quite uncrystallizable.

The latter substance, when long digested with carbonate of barium, produces crystals of a barium-salt whose analysis gives numbers leading to the formula

Co (H4 Ba2) S2 O10

This substance is obviously sulphopropionate of barium, the compound next in series to the sulphacetate discovered by M. Melsens. It is generally deposited from its solution in fine silky crystals, which arrange themselves in spherical groups. They are very stable, and bear a high temperature without decomposition.

The salt associated with the uncrystallizable sulphopropionate of ammonium crystallizes with ease, either in rectangular prisms or in octohedra. Similarly converted into a barium-compound, it was found by analysis to contain at 100° C.,

C4 (H4 Ba2) S4012+2HO.

It forms regular six-sided plates, which are moderately soluble in water, but insoluble in alcohol and in ether. It loses two equivalents of water of crystallization between 100° and 170°, but a few

degrees above this temperature it is decomposed with blackening, yielding water, sulphurous acid, volatile organic products, and sulphate of barium.

We designate this salt as disulphetholate of barium.

Disulphetholic acid is prepared by precipitating a solution of the barium-salt with sulphuric acid, the excess of which is again removed by digestion with oxide of lead, and subsequent treatment with sulphuretted hydrogen. It is a crystalline and stable compound, very acid to the taste, and very deliquescent. With oxide of lead, or with carbonate of silver, it readily forms the respective salts, both of which are crystalline.

After what has been said with reference to the action of sulphuric acid upon acetamide, it is scarcely necessary to remark that the sulphopropionates and disulphetholates may be prepared with equal, or even greater facility from propionamide. Care, however, should be taken to use the amide in a perfectly dry state, which prevents in great measure the formation of free propionic acid.

PROPYLE-SERIES.

Action of Sulphuric Acid upon Butyramide.

Equal parts by volume of melted butyramide and Nordhausen sulphuric acid evolve much heat when mixed together. In the reaction two acids are eliminated, showing that the series bears a strict analogy with the deportment exhibited by the preceding group.

As the ammonia-salts of these acids are wholly uncrystallizable, their separation is almost impossible. The barium-compounds also are scarcely to be obtained of a definite form, so that it is a matter of great difficulty to procure salts of sufficient purity for exact estimation. Recourse was had to fractional precipitation by alcohol.

The first salt which was deposited formed minute grains, which adhered strongly to the sides of the glass vessel containing the solution. It gave a percentage of barium which unmistakeably indicated the formula

which is that of sulphobutyrate of barium.

This substance in its reactions closely resembles (with the exception of its greater solubility in water) the corresponding body of the ethyle-series. It burns like tinder, with evolution of sulphurous acid, and leaves a residue of sulphite and sulphate of barium. The aqueous solution presents a gummy mass on evaporation.

A further addition of alcohol to the mother-liquor of the sulphobutyrate of barium throws down a flocculent precipitate, which is very soluble in water. It was purified by repeated and partial precipitation with alcohol. This substance, when dried at a temperature of 165° C., furnished upon analysis numbers agreeing with the expression

Co (Hg Ba2) S4012'

which is that of disulphopropiolate of barium.