Графични страници
PDF файл
ePub

arsenic acid by dissolving the salt in water, and causing a current of sulphuretted hydrogen gas to pass through it, as long as any precipitate appeared. By this method I threw down a great deal of arsenic, but on filtering and evaporating the liquor, it was still converted into an apple-green matter, and, of course, contained arsenic. I found that when the salt was dissolved in water, the liquid became opaque, owing to a quantity of arsenious acid, which separated from the salt. The liquid being now filtered, to get rid of the arsenious acid, and properly evaporated, yielded a new crop of crystals of sulphate of nickel. These crystals continued to be deposited as long as a single drop of the liquid remained unevaporated. By this method may the whole of the nickel in the speiss be obtained in the state of sulphate of nickel. This sulphate is quite free from arsenic or arsenious acids, for the presence of these acids prevents sulphate of nickel from crystallizing. But for greater security I dissolve the sulphate of nickel in water, and crystallize a second time.

The pure sulphate of nickel thus obtained, is dissolved in water, and decomposed by carbonate of soda. The carbonate of nickel, when well washed and dried, is a light-green powder. I make it up into balls with a little oil, enclose these balls in a charcoal crucible, which is put into a Hessian crucible, the mouth of which is covered and luted. It is now exposed to the greatest heat that I can raise, in a melting furnace for two hours. By this process I have always obtained a button of pure nickel in the metallic state.

The nickel thus obtained is hard, but malleable, and very obedient to the magnet. I think it contains a certain proportion of carbon in combination with the nickel. The button is usually surrounded with a thin dark shining cuticle, which I take to be a carburet of nickel.-Annals of Philosophy.

6. Analyses of Coal.-Dr. Thomson, has lately analysed the varieties of pit-coal, with very extraordinary results.-The species examined were, 1. caking coal, or Newcastle coal; 2. splint coal, or light burn hard coal, being the fifth of the six

Glasgow coal-beds, or the lowest of those now wrought. This coal is the only kind employed at Glasgow, for making coke, and it is also solely used for the smelting of iron. 3. Cherry coal or soft coal; this kind constitutes the greatest part of the four uppermost of the Glasgow beds, especially the third and fourth beds. The Staffordshire coal, too, appears to be of the same kind. 4. Cannel coal.

The earthy part was ascertained by burning a certain portion of each coal; the other elements were ascertained by the products given, when a portion of the coal was heated with the peroxide of copper. The results are that caking coal is composed of 33 atoms carbon...... 24.75......75.28

[blocks in formation]

So that the weight of an integrant particle of caking coal cannot be less than 32.875, and it must be either that number, or a multiple of it.

[merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]
[merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

The singular relation observed between the carbon and the hydrogen surpasses all expectation. It is perhaps the first instance offered to us, where these general elements of animal and vegetable substances, combined in such different proportions, give such similar substances as the four varieties of pit coal; and what increases the wonder is, that Dr. Thomson seems inclined to think that coal is a direct combination of these elements, and not any compound of bitumen, &c., as has been supposed.

7. Analysis of the Water of the Dead Sea, by M. Gay-Lussac.The water had been preserved in a vessel of tinned iron, hermetically closed. When poured out it had no bad or bituminous smell it was slightly turbid, but soon became perfectly clear, M. Bose could not discover any microscopical animals in it. Its taste was very saline and bitter.

Its specific gravity at 17° (62°. 6 Fahr.) was 1.2283. This is sufficient to enable a man to float on the surface of the Dead Sea without motion; but it contradicts the statement of Strabo, who says, that a man may remain upright in it, without sinking below the navel. At present 81 hundredths of his volume would be submerged, and it is not probable that the Dead Sea was more saline formerly than at present.

The water, exposed to a temperature of 7° below freezing (19°.4 Fahr.) did not deposit any salt; so that it is not saturated: it however deposited muriate of soda, at the temperature of 15° (59° Fahr.) when it had lost 4.71 hundredths of its weight.

Saussure's hygrometer, placed in the air in contact with this water, indicated about 82°; so that the air contained only two-thirds of the moisture it would have taken up, if it had stood

over pure water.

From this it results, that the air will not carry off water from the Dead Sea, except when below 82° of humidity, and that it will give water to it, when it is above that point. The borders of the Dead Sea should, therefore, constantly enjoy a dry atmosphere. It is very probable that that sea has

arrived at a fixed degree of saltness, relative to the humidity of the air and its temperature; a conjecture which could be verified if the mean hygrometrical degree at its surface were known.

100 parts of the water gave, by evaporation, a saline residuum, which, when dried perfectly, account being taken of the muriatic acid which the heat disengaged, weighed 26.24. This residuum was composed of

Chloride of sodium, (common salt)...... 6.95
Chloride of calcium (muriate of lime).... 3.98
Chloride of magnesium (muriate of magnesia)15.31

26.24

It contained also, a small quantity of chloride of potassium, (muriate of potash) and traces of a sulphate, probably with a base of lime.

From an examination of the water of the River Jordan, it was found to contain principally common salt, with some muriate of magnesia, a very slight quantity of sulphate of lime, and, probably, also muriate of lime, but in very minute quantity. This salt did not appear to be in the same proportion as in the water of the Dead Sea. The sulphate of lime, for instance, is relatively in more abundance in the first; but it is probable that the large quantity of muriate contained in the latter, prevents the sulphate of lime from remaining in solution.

Annales de Chimie. xi. P. 195.

8. Chesnut Wood substituted for Oak-bark.-There is an account given by Mr. W. Sheldon, in Professor Silliman's Journal, of the chesnut-tree, and the application of its wood to the purposes of tanning and dyeing. By analysis it has been found that chesnut wood contains twice as much tanning as cleaned

oak-bark, and six-sevenths as much colouring matter as logwood. Leather tanned with it is described as superior to that tanned with oak-bark. Ink made with it is admirable, and in dyeing it seems to have a greater affinity for wool than either galls or sumach, causing, therefore, a more permanent colour. The inspissated aqueous extract of the chesnut wood very much resembles catechu; except that, according to Professor Dewey, of William's College, it precipitates a fourth more of gelatine; and in dyeing it is infinitely superior, for it gives the finest black, whilst the colour obtained from catechu is only a meagre olive.

Mr. Sheldon concludes his letter by some details and observations, which will perhaps induce many to receive the more important part of it with caution. On making solutions of the wood, one from the trunk of a tree three feet thick, and another from a limb about three inches in diameter, and precipitating them by the same quantity of solution of gelatine, the precipitates appeared in congeries, bearing a proportion in size to the sticks from which they were obtained. Mr. Sheldon thinks this may lead to a new nomenclature of precipitates, and to the illustration of the compound nature of bodies, and of chemical, or electro-chemical, affinities; and further, that even the size of a stick may probably be ascertained with almost as much precision as by actual admeasurement.

The editor of Silliman's Journal states having verified the most important of Mr. Sheldon's experiments.

9. Maple Sugar.-Experiments were made some years since in France, for extracting sugar from the maple-tree, but they were subsequently abandoned. It appears, however, that in Bohemia better success has been obtained, and that M. Bodard has received important information on the subject. An incision was made in a maple-tree, from which a quantity of syrup issued, which afterwards produced sugar, rivalling, as it is said, that of the beet-root, or the cane.

10. Preservation of Water at Sea.-M. Perinet, after an exa

« ПредишнаНапред »