In Nos. 1 and 2, the temperature never rose to ebullition. The increase is probably from absorption of oxygen from the atmosphere. No. 3 was made with less care, and the matter sometimes boiled; hence more gas was produced-more vapour carried off by it, and less absorption from the atmosphere took place. Nos. 4 and 5 were made at a higher temperature. It follows, however, from the experiments, that if oil be distilled at a temperature a little below ebullition, with the contact of air and necessary precaution, the product equals the weight of the oil employed plus a portion of carbon.

By receiving the products in different portions, it is found that besides water, &c., two kinds of matter are obtained; the first, forming three-fourths of the oil employed, is of a consistence approaching that of lard; yellowish and soft at first, but by degrees acquiring consistency, and becoming very white. At a certain point of time, a yellow tint is again evident, which indicates that the process will soon cease, unless the temperature be increased: this product has a disagreeable, penetrating odour, and is very acid. The second kind of matter is obtained by heating the residue to ebullition; it is liquid, of a yellow amber colour at first, but by contact with air absorbs oxygen, and becomes of a deep brown colour; its odour is less disagreeable than that of the first product. It has an analogy to the empyreumatic oil of amber, and is sensibly acid. Further examination indicated the presence of margaric, oleic, and sebacic acid; a volatile acid; a volatile odoriferous principle not acid, and a fatty matter not acid.

The first product was agitated, and left in contact with cold water. The filtered liquor was acid and odoriferous when distilled; the product was colourless, and contained the volatile acid and the odorous principle. Being saturated with baryta and distilled, the odorous principle passed into the recipient, and the baryta salt being decomposed by phosphoric acid, gave the volatile acid; it somewhat resembles that obtained by M. Chevreul from rancid fat, and by its volatility and oily aspect, when a hydrate resembles the phocenic and butyric acids.

The residue left by distillation of the washing water was, upon

evaporation, found to contain sebacic acid, and an extractive matter becoming brown by contact with air.

. The portion insoluble in water was washed in hot water, and treated with magnesia, which combined with it: boiling water then separated an efflorescent white salt, containing an acid resembling the volatile one described above. The insoluble salts, treated with alcohol, yielded to it a portion of fluid fatty matter, not acid. Ether completed the separation of this substance.

The residue decomposed by muriatic acid, gave a substance composed entirely of margaric and oleic acids.-Annales de Chimie,

xxix. 319.

5. Variations in the Composition of the Atmosphere.-Mr. Dalton states that he has found the oxygen in the atmosphere vary from 20.7 per cent. to 21.15 per cent. The latter was the case on the 8th of January last, the barometer being 30.9, wind N. E.. and very moderate, after three days of calm and gentle frost. The general state of the atmosphere yields only 20.7 or 20.8 per cent. of oxygen.-Ann. Phil. N. S., x. 304.

6. Action of Carbonic Acid on Hydrosulphurets. By M. Henry, jun.-Although M. Chevreul had shewn that carbonic acid is capable of decomposing the hydrosulphurets; yet, when M. Henry advanced the opinion that the sulphuretted hydrogen, disengaged from the mineral waters of Enghien, was owing to the action of free carbonic acid on the hydrosulphurets contained in those waters, it met with considerable opposition; in consequence of which he resumed the subject, and undertook a series of experiments with a view to elucidate it, from which he has deduced the following conclusions:

1. Carbonie acid, in contact with the alkaline or magnesian hydrosulphurets, is capable of decomposing them completely, if the action be continued for a sufficient length of time.

2. The decomposition is effected either by boiling a hydrosulphuret in water impregnated with carbonic acid; or by placing the mixture, without heat, in the vacuum of an air-pump; or by passing a current of carbonic acid gas through a diluted solution of the hydrosulphuret.

3. The hydrosulphurets, obtained by converting sulphates into sulphurets by carbonaceous matter, are less readily acted on.

4. The result of the decomposition of all these salts is the production of carbonates, or rather bi-carbonates; and the quantity of sulphuretted hydrogen disengaged is proportionate to that of the carbonate formed.-Ann. Phil. N. S., x. 381.

7. Inspiration of Inflammable Gas. (Hydrogen?) By Signor Giacomo Cardone.-This experiment was made in consequence of the difference of opinion on the effects of this gas on the

lungs, entertained by Scheele, Fontana, and others. The air was expelled from the lungs as much as possible, the mouthpiece of a bladder containing 30 cubical inches of the gas applied to the mouth, and the gas inhaled at two inspirations. An oppressive difficulty of respiration and a distressing constriction at the mouth of the stomach were the first sensations; these were followed by abundant perspiration, a general tremour over the whole body, seeming to commence at the knees; an extraordinary sense of heat, slight nausea, and violent head-ach. My eyes beheld things but indistinctly, and a deep murmuring sound was in my ears. After a short time, all these effects ceased, except that of heat, which increased in an alarming manner; but ultimately, by the abundant use of cold drinks, I was restored to my original state of health.-Giornale di Fisica, viii. 295.

8. In a Mixture of Muriate of Potash and Muriate of Soda to determine the Proportions of each.-As the nitrate of silver is the most delicate and convenient precipitant, by which we can ascertain the quantity of muriatic acid in combination with these bases; and the quantity united to each being certain, but different (relative to their atomic weights,) which difference is sufficiently great for experimental purposes; hence the quantity in the mixture varies relative to the proportions of each.

The test may be rendered more commodious for analytical experiments, by using it in the state of solution, of known strength or specific gravity, and by means of a graduated tube.

Then let W the number of grains of the mixed salt operated on. a=the grain measures of the test which W grains of (p) would require.

b=the grain measures of the test which W grains of (9) would require.

c the grain measures of the test which W grains of the mixture operated on have required.

Suppose grains of (p) contained in W grains of the mixture. W-x-grains of (7) ditto, ditto.

W.P

Then

Say that 200 grain measures of the test are equivalent to 10 grains of muriate of soda, then 10 grains of muriate of potash would require 157.9 grain measures (nearly) of the same test.

Suppose that we have 178.95 grain measures exhausted in one experiment in 10 grains of a mixture of the two salts

9. On the Solution of Steel and Iron in Acids, and on the residua which remain. By M. Karsten.-M. Karsten observed, as others have done, that the action of acids on steel depends on the hardness of the metal; hard steel being dissolved with great difficulty and slowness in diluted acids. White raw iron shows the same habitudes as steel, but in a more striking manner. Diluted muriatic, or sulphuric acid, has scarcely any effect on it; and the black powder does not appear until weeks have elapsed: strong hot muriatic acid dissolves it, leaving no residuum. Sulphuric acid, in the same circumstances, leaves some carbon, black and of a metallic appearance. Cold nitric acid separates black flakes, which, by long exposure to the acid, become brownish-red. Gray raw iron exhibits very different appearances. Diluted muriatic and sulphuric acids act but slowly, and leave, after months, a carbonaceous residuum in very different conditions; one part is in thin leaves, or scales, lustrous, metallic in appearance, capable of resisting acids and alkalis, not attracted by the magnet, and very slowly combustible in a red-hot crucible: these are graphite. Another part has a similar appearance; but is magnetic, and resembles the residuum from soft steel. A third part is black, not magnetic; colours alkaline solutions black, and is readily consumed by heat and air. Of these three bodies, the graphite is never missing; the others seldom occur together. Strong muriatic acid does not leave so much graphite, part being

carried up by the gas. Strong sulphuric acid leaves graphite, and easily combustible carbon. Nitric acid of specific gravity 1.3, whether urged by heat or not, seems to act irregularly; leaves of graphite being evolved, which as they fall off, or are separated from, the iron, allow the action to be renewed, they seem to form an actual mechanical impediment to the solution; a part of the carbon is dissolved by the acid, and the residuum is mostly graphite mixed with carbon in the state of brown powder.

The graphite thus obtained is insoluble in acids, and alkalis, and quite pure. Heated to redness in the atmosphere, it disappears slowly, leaving no residuum: 18 grains of it placed in a muffle heated to whiteness, required 4 hours for its combustion; it gradually decreased in bulk, produced no flame, and left a minute film of white silica. When the process was interrupted, the only difference seen between the calcined and uncalcined graphite was, that the leaves of the former, if held against the light, appeared transparent in some places, and exhibited a peculiar fibrous struc ture, which the uncalcined portion did not possess: melted with nitre, it was slowly consumed, and the salt remaining, left no residuum in water: heated with sulphate of potash, it did not convert it into sulphite.

Thus, then, the graphite in gray raw iron is not what it has been supposed to be, a combination of carbon and iron, but pure carbon, or its metallic base. Whether natural graphite be also a pure carbon metal, or really a combination of carbon and iron, is yet to be determined.-Phil. Mag. lxvi. 290.

10. Preservative against Rust. Stockholm, 9th Sept., 1825.-M. the Councillor of State of Loevenhielm, Swedish Ambassador in France, during his residence in Paris, received certain propositions from the house of Mazet and Co., tending to give to the proprietors of the mines in Sweden, for the sum of 300,000 francs, a secret; the use of which is, by means of a metallic composition, to preserve all iron goods from rust. The colleges of mines and of commerce, with the Academy of Sciences, and the delegates of the iron-office, were directed to examine these propositions, and they thought fit to adopt them.-Rev. Ency. xxvii. 899.

11. Combinations of Antimony with Chlorine and SulphurThe following estimations of the composition of these bodies is by M. Rose. The crystallized compound of antimony and chlorine, obtained by distilling the pulverized metal with corrosive sublimate, was supposed, from theoretical views, to be a compound of three proportionals of chlorine and one of the metal. It was analyzed by bringing it into solution in water by tartaric acid, preci