Imatges de pàgina

may be immediately prepared, and, by a due observance of the proportions of the tincture, their medicinal quality will always be uniform.

An Examination of different Kinds of Pot-ash, with simple Methods of ascertaining the Proportion of Alkali and of other Salts which they may contain. By M. VAUQUELIN.-M. V. ascertains the quantity of alkali by the proportion of nitric acid required to effect saturation : but, previously, the density of the acid must be determined, as well as the degree of it which is necessary to saturate any given quantity of pure potash. The proportion of sulphuric acid in sulphate of pot-ash is determined by nitrate of barytes, and that of the muriatic in the muriates which may be present, by nitrate of silver. The author then states the proportion of the various substances contained in six species of pot-ash, as follows:

Pot-ash of Russia.

Real Sulphate Muriat Insoluble Carbonic Acid

Potasli. of Pot. of Pot. Matter. and Water. 1152 772 65 5 56 254=1152

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1152 4:4 148 510 34__304=1152 A Letter from M. VAN MARUM to M. Volta, containing an Accourit of some Experiments made with the Electrical Pile.- The facts detailed in this long letter are numerous, but not very striking. We shall thereiore refer our readers to the original.

Report made to the Naticnal Institute on the Experiments of M.. Volta.-In this paper, the principles of M. Volta's theory of the Galvanic Electricity are stated.

Observations on the Coribination of the Tartareous Acid with the... Salifiable Bases, &c. &c. By. M. THENARD.--We noticed a


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report on this memoir in our last Appendix, p. 491. in an article on the Chemical Annals.

Memoir on a new Combination discovered in Zaffre, which M. Brugnatelli has supposed to be Cobaltic Acid. By M. DARRACQ:M. Brugnatelli, in a memoir printed in vol. xxxiii. p. 113. of the Chemical Annals, gave an account of some experiments on the grey oxide of Cobalt, commonly called Zaffre ; from which he inferred that this substance contains a peculiar me. tallic acid, and which he therefore has denominated cobaltic acid. M. DARRACQ, however, on repeating these experiments, has discovered that the acid substance, which combines with ammonia and with water, is not (as M. B. supposed) .cobalt converted by oxygenation into an acid, but an arseniate of cobalt rendered soluble by an excess of the arsenical acid. In order to prove this in the most evident manner by synthesis, M. DARRACO dissolved oxide of cobalt in arsenic acid, evaporated to dryness, and treated the residue with distilled water, after which, this solution was found to possess all the properties of the pretended cobaltic acid.

Extract of a Letter from M. VAN MARUM to M. Berthollet.-M. VAN MARUM here relates that he has produced effects similar to those of the electrical pile of M. Volta, as far as the decomposition of water is concerned, by passing a current of electric cal fluid from a common machine through a tube containing water. He employed, for this purpose, very fine iron wire inserted in thermometer tubes, which were introduced and fixed at a proper distance in the opposite extremities of a larger tube containing the water. This discovery of M. VAN NARUM, however, has been anticipated by the ingenious experi'ments of Dr. Wollaston, published in the Phil. Trans. for 1801, p. 427, which we noticed in our late review of that volume. The only difference is, that the wire employed by Dr. Wollaston was of gold, while the experiments of M. VAN MARUM were made with iron wire.

Description of a Stove on the Principle of the Swedish Fire-place, with Registers to admit warm Air. By M. GUYTON.- This paper cannot be understood without the plate.

Observations on the Proof of Pot-ash, by the Administrator's General of Gun Powder and Salt Petre.- Nitrate of lime has been hitherto employed for this purpose, but nitrate of stron-, tian is found to answer much better. For the particulars, the original memoir must be consulted.

Observations on Dying with Madder; and a simple and certain Mlode of obtaining, with the greatest Beauty and Solidity, the Colour Sec Rev. for March last, p. 300...


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called Adrianople Red. By M. HAUSSMANN.-This paper may perhaps be perused with advantage by dyers, and others who are engaged in similar pursuits.

Extract of a Report on the Oxides of Manganese, which may be employed in the Arts. By M.M. Cordier and BAUNIER.– This investigation was undertaken to ascertain which of the different kinds of manganese, found in the territories of the French Republic, was most proper to be employed in the fabrication of oxygenated muriatic acid.

Exposition of a new Method of separating the Silver which is allozed with Copper in buse Coin. By M. Narioné. The usual mode hitherto employed for this purpose has been liquation with lead, but in many cases it has been found very inadequate. The writer of this paper, therefore, having reflected that sulphur has a greater aflinity for copper than for silver, conceived hopes that, by the addition of this substance, the greater part of the silver would become concentrated in a portion of the copper; so that it might be immediately subjected to cuppellation : while the other part, or matt, being less rich, might undergo the process of amalgamation. He then relates his experiments; from which it appears that this method may be employed on a large scale with much advantage, and that the expense attending it will not amount to one fifth of the cost of ordinary liquation.

Report made to the National Institute, on the Establishment fermed by M.M. ANFRYE and LECOUR to extract the Copper and Tin froin the Scoria of Beli Metal.-These scoria had been abandoned as absolutely useless, and were therefore only employed to repair roads, &c. until M. ANFRYE discovered a method in the dry way, by which from 30 to 40 pounds of tin and copper may be separated from a quintal of the scoria. The process appears to be very simple, nothing more being required to separate the tin from the copper, than to promote the oxidation of the former; and this oxide is afterward separated from the copper by washing. The oxide of tin is then mixed with one-eleventh part of powdered charcoal, and is reduced in a wind furnace.

Note on the Hydro sulphuret of Soda. By M. VAUQUELIN.Having washed a large quantity of soda, in order to extract the carbonate, M. VAUQUELIN observed, at the end of a few weeks, a white salt at the bottom of the mother liquor. This salt was in the form of tetraedral rectangular prisms, terminated by four-sided pyramids; and some were of an octaedral figure. The flavour at first was acrid and caustic, but afterward became extremely bitter, with a slight smell of sulphu


Tated hydrogen gas. The author then relates some experiments which he made on this salt, and which prove it to be an hydro-sulphuret of soda.

Extract of a Letter from Mr. CHENEVIX, of London, to M. Vauquelin.—Mr. C. here acquaints M. Vauquelin that Mr. Hatchett has discovered a new metal, in a mineral from Massachusetts, to which he has given the name of Columbium. This metal is acidifiable, and may be converted into a white oxide and acid. With tincture of galls, it forms a beautiful orangecoloured precipitate ; and, with the prussiates, it produces one of a green colour. It likewise combines with the alkalis, and expels the carbonic acid. Mr. C. also mentions that he has obtained nickel and cobals which were not attracted by the magnet.

A new Mode of forming Ammonia.-M. Lampadius, of Freyberg, has observed that, when crude tartar, or cream of 'Tartar, has been heated until the fame and smoke disappear, ammonia may be obtained by the addition of water.

Observations on some Effects of the Electric Fluid, when put in motion by the Pile of M. Volta. By M. RITTER. The most remarkable of these effects is the following: M. RITTER exposed himself, during one hour, to the action of a pile composed of 100 pieces of copper and zinc; and he felt more pain when he touched the copper than when he touched the side at which the zinc was placed. The arm which had touched the copper experienced a sensation of cold for some time afterward, but the other, on the contrary, felt hot. The arm on the copper side of the pile lost its power of motion, while that on the zinc side seemed to have its strength increased. At the end of an hour he was seized with a diarrhæa, and became much enfeebled; he even felt the effects of this galvanism so much as to be incapable of doing any thing for ten days, and he experienced a remarkable disgust whenever he approached the pile, or any electrical machine. M. Darnim, and some other persons, submitted to the same experiment, and were affected nearly in a similar manner.

Memoir on a native Phosphate of Iron mixed with Manganese. By M. VAUQUELIN.- This mineral, found in the neighbourhood of Limoges, was at first supposed to be an ore of tin; it is of a reddish brown colour, and, when divided into small thin pieces, has a brilliant lustre, and is semi-transparent. It slightly scratches glass; it affords a yellowish grey powder ; and its specific gravity is 3655.

App. Rev. VOL, XXXVII.

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Ву By the blow-pipe, it melts into a black enamel, and does not exhale any odour during the fusion. It is composed as follows: Oxide of iron

31 Phosphoric acid

27 Oxide of manganese

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The author observes that this substance may be very useful for porcelain, &c., since it is easily fused, and produces black, brown, and violet enamels.

Observations on the Acetic and Acetous Acids. By M. DARRACQ. In the commencement of this paper, the author concisely notices the experiments and opinions of M.M. Adet and Chaptal ; and, having afterward related the experiments made by himself, he concludes that there is not any difference in the constituent principles of these acids ;--that water and mucilaginous matter, or extract, are the sole causes of the apparent difference in their properties;— and, consequently, that there exists only one acid of vinegar, which, being at the maximum of oxygenation, ought to be denominated acetic acid.

Observations on the Sap of Asparagus and of Cabbage. By M. Delaville. This paper does not appear to require any particular notice.

Letter of M. DESCROIZILLES.- A bottle, in which was some phosphorus covered with water, was burst by the freezing of the latter ; in consequence, some books and papers were set on fire by the phosphorus, and the author nearly lost his life. He therefore writes this letter as a caution to those who keep phosphorus in the manner above mentioned, and recommends that the bottles should always be placed in copper cases lined with bran and paper.

Memoir on Vegetable Gluten. By M. CADET:-- The experiments made by this gentleman induce him to conclude,

ist. That fresh gluten is insoluble in alcohol.
2dly. That it becomes soluble by the acid fermentation.
3dly. That this solution is precipitated by water.

4thly. That the same, when evaporated to the consistency of a syrup, may be employed as a varnish.

5thly. That colours may be mixed with this varnish.

6thly. That vegetable colours combine preferably with gluten.


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