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mination of the means which are, or may be, adopted for the preservation of fresh water at sea, gives the preference to the following: 1 parts of oxide of manganese in powder is mixed with 250 parts of water, and agitated every 15 days. In this way water has been preserved unchanged for seven years.

The editor of the Annales de Chimie observes, that oxide of manganese has the power, not only of preserving water, but of rendering that sweet which has become putrid; but he also points out the important circumstance, that the oxide is slightly soluble in water, and therefore recommends the use of iron tanks for the water, as in England.

11. Analysis of Sea Water-According to an analysis of sea-water from the Coromandel coast, made by M. Plagne, professor of chemistry, &c., it would appear to contain the following proportions of substances.

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M. Plagne searched diligently for nitrate of potash, but was not able by any means to detect its presence.

12. Titanium in Iron Ores.-M. Robiquet has lately examined the oxidulated octoedral iron, from the steatite of Corsica, and has found it to contain a considerable portion of titanium. It dissolved completely in muriatic acid, but the solution, evaporated to dryness at a moderate heat, and re-dissolved in water, left a white pulverulent substance, which, when fused with potash, and afterwards dissolved in muriatic acid, gave all the characters of a solution of titanium. In this way, six parts have been separated from 100 of the mineral. M. Robiquet is in

duced to suppose, therefore, that titanium generally accompanies the oxidulated iron in nature, and that this compound is not peculiar, as has been supposed, to volcanic countries.

Berzelius found titanium in the iron ore of the Isle of Elba.

13. Chemical Prize Subjects.-The following subjects have been proposed by the Royal Academy of Copenhagen: 1. Nùm principium illud Scytodepsicum, quod ope caloris in materiis vegetabilibus formatur ejusdem est naturæ ac illud, quod ex galla, ex cortice quercûs, etc., extrahitur, an ab hoc discrepat? An et quatenus in arte coriarâ adhibiri potest? Et quæ sunt conditiones, quibus satisfieri debet, ut maximâ quantitate producantur?

2. Mutationes chemicas, quæ in fœno eveniunt, dum inter fermentationem colorem badium contrahit, accurate examinare; nec non investigare, anne ex notitiis rei chemicis indi comparatis utiles quædam regulæ de confectione et usu talis fœni deduci possint?

The prizes attached to these subjects are each of 100 rubles. The papers may be written in Latin, English, French, German, Swedish, or Danish, and are to be sent to M. H. C. Orsted, secretary to the Academy, by the month of December of this year.

14. Strength of Etna Wines.-The following wines were furnished to me by Mr. Ridgway. The specific gravity of the alcohol, of which the proportions per cent. are given beneath, is, 825 at 60° F.

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15. On the Oxidation of Silver and Copper.-In a letter from

S. Lucas, Esq. to Mr. Dalton,

Sheffield, May 31, 1815.

DEAR SIR,-When I had the pleasure of seeing you in Man

chester, I mentioned having observed that pure silver, when melted, and while in a fluid state, had the property of uniting with a small proportion of oxygen, not only from the atmosphere, but also from other bodies which gave it out at a suitable degree of heat, as some of the nitrates for instance; and that the oxygen thus absorbed remains united with the silver only so long as it continues in a fluid state, or while fluid, until some substance be applied, having a more powerful attraction for the oxygen. In proof of this, I now send, for your inspection, a few specimens of silver that has been in the different states, and which carry the external marks and also a bottle of the gas collected from silver, which had been exposed to the influence of the atmosphere by cupellation.

If silver in large quantities, after having been exposed in a melted state to a current of oxygen gas or atmospheric air, be allowed gradually to cool, the surface first becomes fixed or solid; this soon bursts, ebullition ensues, and an elastic vapour in considerable quantity escapes, driving before it a portion of the internal fluid metal, which, becoming solid as it is brought to the surface, produces the protuberances as shewn by the accompanying specimen, No. 1. This ebullition continues from

to an hour or more, according to the quantity of silver, and the rapidity with which it is cooled.

If, instead of cooling gradually, it be made to assume the solid state suddenly by pouring it into water, still the same phenomena occur; an ebullition takes place, and oxygen gas is evolved, but as the silver is so much divided, and passes so suddenly from the fluid to a solid state, the protuberances are proportionably minute, and are spread more equally over the whole surface, as will be seen in specimen No. 2.

No. 3 shews the arrangement of crystallization, which the silver assumes when the gas is separated from it, during the time of its becoming solid.

I have before observed, that substances having a powerful affinity for oxygen, will take it from the silver, even while in a fluid state. Thus, if charcoal be spread, for a few moments only, on the surface of silver that has absorbed oxygen, the whole

of the oxygen will immediately be taken from it; no ebullition or escape of gas occurs, whether it be cooled gradually, as in specimen No. 4, or when poured into water, as in No. 5. By comparing these two specimens with Nos. 1 and 2, a very great difference will be observed, which is occasioned wholly by the escape of gas from the latter, while no such circumstance attended the former.

The bottle of gas which you will receive herewith, was collected in the following manner. Some silver, after cupellation, till in a state of perfect purity, was poured, by a few pounds at a time, into a vessel containing about 30 gallons of water, and an inverted bottle previously filled with the water, and with a funnel in its mouth, being instantly placed over the silver, as it was each time poured into the water, the gas, as it was given out and arose from the silver, was thus collected in the bottle until it was filled.

Care is necessary, that the neck of the bottle be kept below the surface of the water to prevent the access of atmospheric air, and I am not very certain that there is not a little admixture *.

In addition to the above, I have enclosed two samples of copper, in two different states, both, however, equally pure, except that the one is believed to be combined with oxygen, and the other not.

No. 1, is a sample taken from a furnace-full of about 5 cwt., when in a melted state, and which had been exposed uncovered to a current of atmospheric air for about two hours before and during the time it was melting. This, when poured into water exploded most violently, as will be seen by the small, which was attempted to be granulated.

The specimen No. 2, is a sample from the same copper, after the surface had been covered with charcoal for about half an hour. This, you will perceive, is in a very different state from the other, and, when poured into water, granulated without any explosion, as the small bits will shew. I remain, &c.

(Manchester Transactions.)

SAMUEL LUCAS.

* I found this gas to contain 86 or 87 per cent, of oxygen, J. D.

§ 2. MINERALOGY, GEOLOGY, &c.

1. Native Carbonate of Magnesia.-This substance has lately been discovered at Hoboken, in Staten Island, at the same place where the hydrate of magnesia was found by Dr. Bruce. It occurs in horizontal veins about two inches thick, in a serpentine rock. At first it was soft, white, and slightly adhesive; but when dry it easily rubbed to powder. It is perfectly soluble with effervescence in sulphuric acid, yielding, on evaporation, crystals of sulphate of magnesia. More lately, the same gentleman has discovered in the same place, veins of carbonate of magnesia, in fine acicular crystals. They were grouped in minute fibres, radiating from the sides; sometimes the crystals were suspended, and assumed the stalactitic form.

2. Analysis of the Euclase, by M. Berzelius.-I owe to the generosity of M. de Souza, formerly ambassador from Portugal to France, the specimen of this rare stone, which I have employed for an analytical experiment. The stone reduced to powder was heated with carbonate of soda, in a platinum crucible, and then being acted on by dilute muriatic acid, left a light white powder, which was separated; the fluid was evaporated to dryness, and treated as is usual in analyses of the emerald. The powder, insoluble in muriatic acid, resembled oxide of tantalium. It was heated with super-sulphate of soda; a portion dissolved, but as the whole of the saline mass was soluble in water, the powder could not be oxide of tantalium. A current of sulphuretted hydrogen gas was passed into the solution, and threw down a yellowish precipitate, which, after being dried and weighed, was entirely reduced before the blow-pipe, and gave a globule of tin. The fluid, precipitated by the gas, gave, with ammonia, a precipitate soluble in carbonate of ammonia. It was glucine. I have thought it right to notice this property which glucine has of giving, with oxide of tin, a combination which resists for a long time the action of acids, because, in the analysis of the gadolinite of Kovarfurt, the same thing happened to me with a combination between glucine and the oxides of manganese and ce

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