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separated, and sulphuric acid added to separate the excess of lead, and then by filtration a clear solution was obtained.

The next object, was, to separate the nickel from the solution, and this Dr. Vest directs to be done, by forming it into a triple salt with sulphate of potash. The solution obtained as above was concentrated, that a portion of a salt of Vestium in fine white needles might fall down, but this did not happen. It was then diluted, decomposed by potash, the precipitate washed, and dissolved in sulphuric acid, and the excess of acid saturated by potash; then more sulphate of potash was added, and the whole was evaporated, and left to crystallize. After some time the

crystals that had formed were separated from the solution, and washed with cold water, and the washings being added to the mother liquor, with more sulphate of potash, it was again evaporated and crystallized. This was repeated three or four times, until sulphate of potash separated no more nickel from the solution; and now, according to Dr. Vest, I ought to have had in the solution sulphate of vestium, moderately free from other metals.

I looked eagerly for the white flocks, which are described as forming a salt of Vestium on the crusts of triple sulphate of potash and nickel, in the above process of purification, but could not observe any. I dissolved all the crusts, and re-crystallized them two or three times over, that any salt of vestium contained in them might be separated, but did not procure the flocculi as I expected; I obtained, however, a residuary solution (being the mother liquor) similar to the one mentioned above.

These solutions, being added together, were precipitated by carbonate of potash, and boiled in excess of it; the precipitate was washed, heated red hot, digested in cold diluted muriatic acid, and the green solution which was produced poured off from the portion which remained undissolved; the solution contained nickel and cobalt. The undissolved part was boiled with muriatic acid and dissolved, forming a solution which ought to have been the muriate of vestium.

The solution I had thus obtained by Dr. Vest's process, was in very small quantity, but I hoped to be able to ascertain Vestium in it. It had a faint yellowish green colour. It was evapo

rated to dryness, and re-dissolved several times, but no white flocks separated, as was expected from Dr. Vest's description. It agreed with the account of Vestium, in being precipitated by prussiate of potash, white, and by sulphuretted hydrogen, dark, brown, and black. It was precipitated by ammonia, and dissolved in excess of ammonia. It was precipitated by carbonate of ammonia, and dissolved in excess of the carbonate, nor was it thrown down by oxalate of ammonia. Not perceiving any thing, however, in these phenomena different to what might be expected from a weak solution of nickel and cobalt in muriatic acid, I endeavoured to separate my supposed solution of Vestium into these two metals, and by means of Mr. Phillips's method, easily succeeded. Having gathered all the tested solutions that had not had other metals put into them together, I evaporated to dryness, drove off ammoniacal salts and volatile acids, separated the other acids by potash, washed the oxide, and dissolved it in muriatic acid, and then added ammonia in such excess as to dissolve the precipitate at first formed; solution of potash being then added, a precipitate fell, which was found to be nickel; a little cobalt remained in solution, and my Vestium entirely disappeared.

Dr. Vest has not said how much Vestium is contained in the nickel ore of Schladming, though the quantity is stated to be variable, and it is barely possible I may have missed the metal from its existing in very minute proportions. In following, however, the process recommended by the discoverer, I ought to have obtained it, though I do not think that process the best that could have been devised. The whole description of the metal in Dr. Vest's paper appears to be very indefinite; there is no decided and constant difference established between it and the other metals; and in examining both the regulus and its ore, obtained from Dr. Vest, I have met with no experimental evidence of its existence as a simple and new metal.

ART. X. On the Carbonates of Ammonia and of Soda. By Richard Phillips, F.R.S.E. F.L.S. M. Geol. Soc., &c.

DURING Some late researches, my attention being directed to the composition of the carbonates of ammonia, I began, and had nearly completed, an examination of them, before I observed that they had been recently analyzed by Dr. Ure*; and I consider his results to be so nearly accurate, that I should have suppressed mine, if I had not noticed some circumstances respecting the compounds in question, which have, I believe, hitherto escaped observation. I am the more anxious to state the true nature of what is usually termed subcarbonate of ammonia, because, in my remarks upon the London Pharmacopaia, I have given an incorrect estimate of its composition.

My present communication will not contain any observations upon those salts which result from the direct combination of carbonic acid with ammoniacal gas; the constitution of these is well known, and they are represented, on the synoptic scale, by 49 for the carbonate, and 76.5 for the bicarbonate of ammonia. The ammoniacal carbonate, which I first examined, is that obtained by the mutual decomposition of carbonate of lime, and muriate of ammonia; it is usually called sub-carbonate of ammonia, and this appellation I shall for the present adopt.

It will appear, by the synoptic scale, that, if no loss occurred during the decomposition of the carbonate of lime, and muriate of ammonia, the carbonate of ammonia obtained would consist of

One atom of carbonic acid...... 27.54

One ditto of ammonia.....

One ditto of water

....

21.50

....

45.62 35.62

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In order to compare the theoretical with the actual product of the operation, the following experiments were made:

One hundred grains of compact translucent subcarbonate of

*Annals of Philosophy, Vol. X. p. 203.

ammonia were dissolved, with the usual precautions, in dilute sulphuric acid; 54.2 grains of carbonic acid gas were evolved.

One hundred grains of the same salt were dissolved in water, and added to a neutral solution of muriate of lime; some effervescence was excited, and the carbonate of lime precipitated after the application of heat, and dried, weighed 86 grains; according to the scale, 63 of carbonate of lime are equivalent to 21.5 of ammonia; consequently,86 indicate 29.3.

According to these experiments, 100 parts of subcarbonate of ammonia appear to consist of

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By referring to the Synoptic Scale, it will be seen that the atomic constitution, and exact composition of this salt, are as follow :

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On the scale it will be represented by 41.31 + 21.5 + 11.32 74.13, or 14 portion of carbonic acid, one of ammonia, and one of water.

It is well known that when this carbonate of ammonia is exposed to the air, it becomes inodorous, and ceases to act upon turmeric paper. To examine the salt thus procured, the following experiments were performed:

One hundred grains of the inodorous salt were cautiously dissolved in dilute sulphuric acid; 55.8 grains of carbonic acid gas were evolved. An equal quantity of the same salt was dissolved in water, and added to a neutral solution of muriate of lime; considerable effervescence was excited, and, by heating the mixed solutions, 62 grains of carbonate of lime were precipitated; as 63 of carbonate of lime are equivalent to 21.5 of ammonia, 62 in

dicate 21.16. It appears, therefore, that the inodorous salt is

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By the scale it will be seen, that its atomic constitution and composition are as follow:

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It is therefore bicarbonate of ammonia, combined with two atoms of water; on the Synoptic Scale it will of course be represented by 99.22. On considering these statements, it will be observed that, when carbonate of lime and muriate of ammonia decompose each other, the following arrangements take place: One atom of water

One ditto ammonia, are dissipated during sublimation;
One ditto carbonic acid

One ditto ammonia, are dissipated by exposure to the air;
Two atoms carbonic acid

One atom ammonia.

Two atoms water remain in combination, forming inodorous bicarbonate of ammonia; and it is evident that the pungency of subcarbonate of ammonia depends upon the constant dissipation of carbonate of ammonia, which occurs until bicarbonate only is left.

On mentioning some of the facts now detailed to Mr. Philip Taylor, he informed me that, in attempting to prepare bicarbonate of soda in the mode recommended by M. Berthollet, he procured a salt evidently different from carbonate of soda, but too distinctly retaining alcaline properties to be considered a bicarbonate.

Upon examining this salt, I found that it consisted of minute prismatic crystals, the most regular of which appeared to consist of rhomboidal prisms, of about 60° and 120°, terminated by quadrangular pyramids, the planes of the pyramids replacing the solid angles of the prism.

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