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fated by zinc, while our oxide is thrown down black. There
These properties induced me to consider the substance Supposed a which I had obtained from the Greenland mineral as the new metal. oxide of a metal hitherto unknown; and I proposed to distinguish it by the name of junonium.
In the experiments above detailed, I had expended almost Juhonium. all the oxide of junonium which I had in my possession, taking it for granted, that I could easily procure more of it from the Greenland mineral. But, soon after, I was informed by Mr. Wollaston, to whom I had sent a specimen of the mineral, that he had not been able to obtain any of my supposed junonium in his trials. This induced me to repeat the analysis no less than three times, and in neither case was I able to procure any more of the substance, which I described above. Thus, it has been out of my power, to verify the preceding details, and to put the existence of a new metal in the mineral beyond doubt. At the same time I may be allowed to say, that the above experiments were made with every possible attention on my part, and most of them were repeated, at least a dozen times. I have no doubt myself of their accuracy; but think that the existence of a new metal can hardly be admitted, without stronger proofs than the solitary analysis which I have performed.
5. The liquid, thus freed from iron and junonium, was Alumine. supersaturated with pure ammonia. A grayish white gelatinous matter precipitated. It was separated by the filter, and became gradually darker coloured when drying. This matter, after being exposed to a red heat, weighed about 38 grains. When boiled in potash lie, 41 grains were disselved, of a substance which, separated in the usual way, exhibited the properties of alumina.
6. The remaining 33.9 grains were again dissolved in An oxide, muriatic acid, and precipitated by pure ammonia. The precipitate was separated by the filter, and allowed to dry spontaneously in the open air. It assumed an appearance very much resembling gum arabic, being semitransparent, and of a brown colour. When dried upon the sand-bath, it became very dark brown, broke with a vitreous fracture, and still retained a small degree of transparency. It was
examined by reagents,
respects from that of ce
tasteless, felt gritty between the teeth, and was easily reduced to powder. It effervesced in sulphuric, nitric, muriatic, and acetic acids, and a solution of it was effected in each by means of heat, though not without considerable difficulty. The solutions had an austere, and slightly sweetish taste, When examined by reagents, they exhibited the following properties:
(1.) Prussiate of potash. A white precipitate. (2.) Oxalate of ammonia. A white precipitate. (3.) Tartrate of potash. A white precipitate. (4.) Hydrosulphuret of potash. A white precipitate. (5.) Phosphate of soda. A white precipitate. (6.) Arsenate of potash. A white precipitate. ⚫ (7.) Potash and its carbonate. A white precipitate, (8.) Carbonate of ammonia. A white precipitate. (9.) Ammonia. A white gelatinous precipitate, (10.) A plate of zinc. No change.
These properties indicated oxide of cerium. I was there differ in some fore disposed to consider the substance which I had obtained as oxide of cerium. But on perusing the accounts of that substance, given by the celebrated chemists to whose la bours we are indebted for our knowledge of it, there were several circumstances of ambiguity which occurred. My powder was dissolved in acids with much greater difficulty than appeared to be the case with oxide of cerium. The colour of my oxide, when obtained from oxalate, by exposing it to a red heat, was much lighter, and more inclined to yellow, than the oxide of cerium.
In this uncertainty, Dr. Wollaston, to whom I communicated my difficulties, offered to send me down a specimen of the mineral called cerite, that I might extract from it
real oxide of cerium, and compare my oxide with it. This but this owing offer I thankfully accepted ; and upon comparing the proto the method perties of my oxide with those of oxide of cerium, extracted was procured. from cerite, I was fully satisfied that they were identical. The
in which it
. The specimen of cerite, which I analysed, was so much mixed with actonolite, that the statement of the results which I obtained cannot
more difficult solubility of mine was owing to the method I had employed to procure it, and to the strong heat to which I had subjected it; whereas the oxide of cerium from cerite had been examined in the state of carbonate.
it not before
7. In the many experiments made upon this powder, and Some partien. upon oxide of cerium from cerite, I repeated every thing that lars respecting had been established by Berzelius and Hisinger, Klaproth noticed. and Vauquelin, and had an opportunity of observing many particulars, which they have not noticed. It may be worth while, therefore, without repeating the details of these chemists, to mention a few circumstances, which will be found useful in examining this hitherto scarce oxide.
a. The precipitate occasioned by the oxalate of ammonia is at first in white flocks, not unlike that of inuriate of silver, but it soon assumes a pulverulent form. It dissolves readily in nitric acid, without the assistance of heat. The same remark applies to the precipitate thrown down by the tartrate of potash. But tartrate of cerium is much more soluble in acids than the oxalate.
b. The solution of cerium in acetic acid is precipitated gray by infusion of nut-galls. Cerium is precipitated likewise by the same reagent from other acids, provided the solation contains no excess of acid. This fact was first observed by Dr. Wollaston, who communicated it to me last summer. I immediately repeated his experiments with success.
c. Cerium is not precipitated from its solutions in acids by a plate of zinc. In some cases, indeed, I have obtained a yellowish-red powder, which was thrown down very slowly. But it proved, on examination, to consist almost entirely of red oxide of iron, and of course only appeared when the solution of cerium was contaminated with iron.
be of much importance. The specific gravity of the specimen was 4·149,
A white powder, left by muriatic acid, and presumed to be silica, 47-3
Essential cha racters of ceUn,
d. The solutions of cerium. in acids have an astringent. taste, with a perceptible sweetness, which, however, is different from the sweetness, which some of the solutions of iron in acids possess..
e. The muriate and sulphate of cerium readily crystallise; but I could not succeed in obtaining crystals of nitrate: of cerium.
f. The best way of obtaining pure oxide of cerium is, to of obtaining precipitate the solution by oxalate of ammonia, wash the precipitate well, and expose it to a red heat. The powder obtained by this process is always red: but it varies very, much in its shade, and in its beauty, according to circum stances. This powder always contains carbonic acid. g. I consider the following as the essential characters - of cerium. The solution has a sweet astringent taste. It is precipitated white by prussiate of potash, oxalate of ammos ria, tartrate of potash, carbonate of potash, carbonate of ammonia, succinate of ammonia, benzoate of potash, and hydrosulphuret of ammonia. The precipitates are redis.. solved by nitric or muriatic acids. Ammonia throws it down in gelatinous flocks. Zine does not precipitate it? at all.
h. The white oxide of cerium, mentioned by Hisinger and Berzelius, and described by Vauquelin, did not present itself to me in any of my experiments: unless the white flocks precipitated by ammonia from the original solution be considered as white oxide. They became brown on drying, and, when heated to redness, were certainly converted into red oxide.
As cerium, as well as iron, is precipitated by succinate of ammonia, the preceding method of separating the two from each other was not unexceptionable. Accordingly, in some subsequent analyses, I separated the cerium by means of oxalate of ammonia, before I precipitated the iron. I found, that the proportions obtained by the analysis above described were so near accuracy, that no material alteration is necessary.
8. The liquid, thus freed from iron, alumina, and cerium, was mixed with carbonate of soda. It precipitated a quantity of carbonate of lime, which amounted, as before, to
bout 17 grains, indicating 9.2 grains of lime.
From the preceding analysis, which was repeated no less han three times, a different method being employed in ach, the constituents of allanite are as follows:
I omit the 7 grains of junonium, because I only detected it in one specimen of allanite. The excess of weight in the preceding numbers is to be ascribed, chiefly to the carbonic. acid combined with the oxide of cerium, from which it was not completely freed by a red heat. I have reason to believe, too, that the proportion of iron is not quite so much as The iron probably over25-5 grains. For, in another analysis, I obtained only 18 rated. grains, and in a third 20 grains. Some of the cerium was perhaps precipitated along with it in the preceding analysis, and thus its weight was apparently increased.
Observations on Three Papers of Mr. DAVY. By Messrs.
IN the Annales de Chimie for September last are transla- Mr. Davy's
tions of three papers by Mr. Davy, sent to France, by that observations gentleman, and entitled, 1. Observations on the Researches on the reof Messrs. Gay-Lussac and Thenard relative to the Amal- Gay-Lussac gam furnished by ammonia. 2. Examination of some and Thenard Observations of Messrs. Gay-Lussac and Thenard on the, Facts respecting the Metals of the Alkalis. 3. Reply to
Abridged from the Annal. de Chim. vol. LXXV, p. 290.