What

grains. The brine is converted into salt by evaporation on artificial hedges of blackthorn, 25 feet high, and 3 feet thick; of which there are two rows, extending beneath sheds 6262 feet, or nearly a mile and a quarter in length. After 6 falls in the process, the brine contains 17 per cent. of salt, instead of 2. From 2,600 to 2,800 cwt. of salt are thus extracted from the brine, or even 3,000. a vast charge of water the atmosphere has carried off by this easy process! By the analysis, we see that 14 grains of muriate of soda are combined with 976 or water, or 70 times its weight; hence, besides all loss in manufacturing, 210 millions of pounds of water are annually disposed of; and since the brine is seven times stronger after spontaneous evaporation than before, (rising from 2 to 17 per cent.), sixsevenths of the water are driven off during this process. Hence, during that part of the year in which the manufacture continues, (for, during many winter months the frost renders it impossible,) the atmosphere actually absorbs 180 millions of pounds of water in the form of invisible vapour. The volume of this is three millions of cubic feet in round numbers, a quantity which, if uniformly distributed over the area of the thorny stacks through which it percolates, would reach the astonishing depth of 681⁄2 feet, or more than twice and a half that of the thorns themselves. - Abridged from Jameson's Journal.

ANALYSIS OF HAILSTONES.

M. GIRARDIN, in a letter to M. Arago, read at the French Academy of Sciences, on April 22, gives the result of his analysis of hailstones collected by him in the preceding February. The hailstones were first put into a bottle, washed with distilled water, and weighed 500 grains; the hail readily dissolved, and the liquid resembled water into which a few drops of milk had been let fall; it was turbid and whitish. Gradually there were formed in it a considerable number of white and very light flocks, which soon became one cloudy mass, and deposited at the bottom of the vessel. Next morning the liquor was perfectly limpid.

M. Girardin then details some beautiful experiments with the hailwater, the re-agents employed by him being nitrate of silver, oxalate of ammonia, nitrate of barytes, and nitric acid. It follows, that the hailstones so examined contained a considerable portion of organized and azotized matter, a sensible quantity of lime and sulphuric acid, but no sensible trace of ammonia.

Several chemists have directed their attention to the existence of an organic substance and saline matters in the atmosphere. Their experiments have proved that rain, in falling through the atmosphere, carries with it in solution, into the earth, ammoniacal salts, calcareous salts, and a fleecy matter, which is, without doubt, the origin of the deleterious principles which are designated by the term miasmata. Hitherto, however, no one has stated the existence of this organic matter in hailstones. Journal de Pharmacie; Philos. Mag.

METEORIC IRON.

PROF. SHEPHERD, of South Carolina, has detailed to the British Association an analysis of Meteoric Iron, in which he has detected new elements, viz., chlorine and silicon. There were also exhibited some specimens of native terrestrial iron, the existence of which had been doubted. One had been found in Connecticut, and another in Pennsylvania. The latter was arseniuretted native iron. No traces of nickel or cobalt could be detected in either.

CONSTITUTION OF RESINS.

MR. F. W. JOHNSTON has submitted to the Royal Society three papers on this inquiry, with tabulated results of chemical examinations. The author's general conclusions are the following:

1. Many of the resins may be represented by formulæ, exhibiting their elementary constitution, and the weight of their equivalents, in which 40 C is a constant quantity.

2. There appear to be groups, in which the equivalents, both of carbon and hydrogen, are constant, the oxygen only varying; and others, in which the hydrogen alone varies, the two other elements being constant.

In the third part of the same series of investigations, the author examines the constitution of the resin of Sandarach, of commerce, which he finds to consist of three different kinds of resin, all of which possess acid properties. In like manner, he finds that the resin of the pinus abies, or spruce fir, commonly called Thus, or ordinary Frankincense, consists of two acid resins; the one easily soluble in alcohol, the other sparingly soluble in that menstruum. The gum resin olibanum, of commerce, was found to consist of a mixture of at least two gum resins, the resinous ingredient of each of which differs from that of the other in composition and properties.-Athenæum.

NEW RESIN.

ON April 20, Mr. Solly read to the Asiatic Society, an account of a New Resin, for specimens of which he was indebted to Dr. Babington. He stated that it was wholly unknown in this country; and the only author he was acquainted with by whom it had been mentioned was Dr. Ainslie, who, in his Materia Medica of Hindostan, described it as a substance similar to myrrh, and employed in native medicine, under the name of Cumbi Gum. Mr. Solly described, at length, its properties and nature, and the difference between it and gum myrrh. He stated that it was a resin, and not a gum-resin, and dissimilar to all the resins now known. In the state in which it had been brought over, it was mixed up with a considerable quantity of impurities, amounting to nearly 17 per cent. When purified, it was of a deep amber colour, brittle, easily fusible, and combustible; easily soluble in alcohol, and insoluble in water and caustic potassa. From the virtues attributed to it in India for various purposes, and, amongst others, in several diseases of cattle, he thought it reasonable to expect considerable medicinal powers, and stated that experiments on its properties were in progress.

RESIN OF BENZOIN.

M. BERZELIUS has asserted that the Resin of Benzoin, on distilla

tion, furnishes an oil, which, like that of bitter almonds, is, by long contact with the air, converted into Benzoic acid. Since then, M. Frenéy has shown that this oil is changed into Benzoic acid under the influence of potass. M. Auguste Cahours has been making farther experiments, with the following results: in a pure state this oil is limpid, colourless, a little soluble in water, to which it communicates its odour and its flavour: it is soluble in alcohol and ether in every proportion; its odour is sweet and aromatic, its flavour acrid and burning, its specific gravity greater than that of water, and it boils at about 205.-Athenaum.

BORING ROCKS BY CHEMICAL AGENCY.

M. PRIDEAUX has found that a stream of hydrogen oxygen gas applied to a piece of granite soon produced heat; and that, on the application of cold water, the stone became soft and yielded to the tool. The oxygen might be superseded by common air from a pair of double bellows; and the common coal gas would be found better than hydrogen, because it contained more inflammable matter in a given space; and it might be procured from any neighbouring gas-works, and conveyed down into a mine in a copper vessel. If oxygen gas should be found absolutely necessary, nothing was easier to procure where there was a steam-engine; they had only to get a little iron retort, and, in a county like Cornwall, abounding with manganese, they need never be at a loss for oxygen gas. He did not, however, suppose, in the present state of underground management in our mines, this plan would be adopted; but he was of opinion, should the Mining School be continued for two or three years, there would soon be many young men ready to carry it into effect. - Proceedings of the Royal Cornwall Polytechnic Society.

ALKALINE AND EARTHY BODIES IN PLANTS.

On March 14, was read to the Royal Society a paper by Robert Rigg, Esq., to show that the solid materials which compose the residual matter in the analysis of vegetable substances, and which consist of alkaline and earthy bodies, are actually formed during the process of fermentation; whether that process be artificially excited, by the addition of a small quantity of yeast to fermentable mixtures, or takes place naturally in the course of vegetation, or of spontaneous decomposition. His experiments also show this formation of alkaline and earthy bodies to be always preceded by the absorption of carbonic acid, whether such acid be naturally formed or artificially supplied. This combination takes place to a greater extent during the night than in the day; and in general, the absorption of carbonic acid by the soil is greater in proportion as it is more abundantly produced by the processes of vegetation; and, conversely, it is the least when plants decompose this gas, appropriating its basis to purposes of their own system. Hence Mr. Rigg conceives there to be established in nature, a remarkable compensating provision, which regulates the quantity of carbonic acid in the atmosphere, and renders its proportion constant.Proc. Royal Soc.; Philos. Mag.

GRADUATING GLASS TUBES.

MR. C. T. COATHUPE has detailed to the British Association an improved method of Graduating Glass Tubes for Eudiometrical Purposes. His apparatus for this purpose consists of a truly-bored cylindrical tube of iron, into which an iron piston is accurately fitted. Upon the rod of this piston a screw is cut, with a good pair of dyes, throughout its entire length. The rod is then filed of a triangular form, leaving sufficient of the threads of the screw at the rounded angles for an iron nut to traverse with security and freedom. To the upper extremity of this iron cylinder, a cap of the same metal is screwed, and into this cap is screwed an iron stop-cock. To the stop-cock is attached a glass graduated measure, with a narrow lip, by means of an iron connecting socket. Near the opposite extremity of the cylinder, an iron diaphragm, of about a quarter of an inch in thickness, is inserted, and is fastened in its place by a side screw or pin; and through this diaphragm a triangular-shaped hole is made, through which the piston-rod can slide easily up and down, but without lateral shake. Below the diaphragm, and at the extremity of the cylinder, the nut is inserted, whose action propels or retracts the piston without the possibility of the piston itself deviating from a right line. This nut enters the cylinder to the depth of about half an inch; and around the entering part a deep groove, in the form of the letter V, is turned; into which the pointed ends of three steel screws enter through the exterior of the cylinder at equal distances, in such a manner that the nut can be revolved freely, but cannot be otherwise displaced. From the entering part of the nut a projecting portion forms a shoulder, which is graduated in equal parts: which projecting portion may be of any diameter greater than that of the cylinder. On the exterior of the cylinder an index is fixed, by means of which any number of revolutions of the nut, or any number of equal parts of a revolution, can be ascertained.

To prepare this instrument for use, the piston is to be retracted to its lowest position, and the cylinder is to be filled with mercury, (without air bubbles,) by pouring a sufficient quantity of this metal into the graduating glass that is attached to the stop-cock, and turning the plug for its admission within the cylinder. If, when the cylinder is full, and while some mercury still remains within the graduated glass measure, we turn back the plug of the cock, we get the air-way of the plug filled with mercury: and by pouring off the superfluity, we have the instrument in a proper state to commence graduating any tube for laboratory purposes. Thus, if the tube to be graduated be about one-third of an inch in diameter, and we open the communication between the cylinder and the measure, and propel the piston by one whole turn of the nut, and then close the communication between the cylinder and the measure, by turning the plug of the cock, we have within the measure a quantity of mercury, which, when poured into the tube to be graduated, will give a tolerably long space for the first division; and such similar spaces may be respectively marked, by repeating the process until the whole tube be divided.

CHEMICAL ABACUS.

DR. REID, of Edinburgh, has found this apparatus useful in introducing his pupils to a precise knowledge of the constitution of the more important chemical compounds. It consists of a frame of wood, across which wires are placed, and upon which beads are strung, as in the instrument employed by Chinese clerks, and to be seen in most museums. Each wire corresponds to a chemical element, and the beads to atoms; while the names of the elements are placed on the frame at the extremities of the wires. Dr. Daubeny has suggested an improvement of this instrument, by having the beads of different colours to correspond to the different elements. [The Chemical Abacus may now be seen at most of the philosophical instrument-makers' in the metropolis.]

MODE OF ANALYZING GERMAN SILVER. BY J. C. воотн.

THE following method of analysis may be successfully practised by any one who possesses a little chemical knowledge. A small piece of about 20 grains is dissolved in nitro-muriatic acid with the assistance of a gentle heat, by which means the metals will be converted into chlorides. If the solution be filtered through a small paper-filter, and a white powder remain after washing with water, it is the chloride of silver, the presence of which metal in the compound is accidental and scarcely appreciable. The acidulated solution is then treated with sulphuretted hydrogen, which separates copper and a little arsenic. The sulphuret of copper is collected on a filter, treated with nitric acid in a gentle heat, till the sulphur appears whitish, then filtered, brought to boiling, precipitated with caustic potass, filtered, and weighed. 100 parts of this precipitate contain 79.83 of metallic copper. To the solution after filtering off the sulphuret of copper, a little nitric acid is added, and the whole heated in order to convert the protoxide into the peroxide of iron. Muriate of ammonia is then added to the same, and a small excess of ammonia, which precipitates only the peroxide of iron. This may be collected on a filter and weighed: 100 parts of it contain 69.34 of metallic iron. The solution is now to be treated with carbonate of soda, and evaporated to dryness; the dry mass is treated with hot water, and the residue washed and dried. This powder, consisting of carbonate of zinc and nickel, is mixed with half its weight of saltpetre, and ignited until the whole is nearly dry. It is transferred to a filter after being powdered in a small mortar, and is then washed two or three times with pure, but dilute, nitric acid, which dissolves the oxide of zinc, and leaves the peroxide of nickel. To the zinc solution carbonate of soda is added, the whole evaporated to dryness, treated with hot water, and the remainder after being dried and ignited is weighed: 100 parts contain 80-13 metallic zinc. The peroxide of nickel is dissolved in hydro-chloric acid, precipitated by caustic potassa, filtered off and weighed: 100 parts of it contain 78-71 metallic nickel.

The separation of nickel and zinc is ever attended with difficulty and some uncertainty, but it is rendered much more simple by the method above proposed, and which is not more inaccurate than others

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