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WELTER'S SELF-ACTING APPARATUS FOR COMBINING GASES WITH LIQUIDS.

Description of the Plate. Welter, says the French author from whom we borrow this description, displays genius in all his inventions, and he has found out a very convenient apparatus for the preparation of the saturated carbonates, which also answers for many other purposes. When this apparatus is once prepared, the operation goes on of itself, without requiring the aid of the operator till the materials are exhausted, and without the loss of any gas. The vessel, E, provided with three mouths, one below and two above, is filled with marble broken into pieces. With each of these mouths bent tubes are connected, as seen in the plate. No. 1 is to carry the carbonic acid gas to the bottom of a tub, filled with a concentrated solution of carbonate of potass; No.2 is to convey, by a small opening-, G, the acid to the carbonate of lime; No.3, by giving it the proper degree of inclination, is made to carry off the solution of muriate of lime as soon as it reaches a certain height. A mixture of equal parts of water and muriatic acid is poured into a vessel with two mouths, F. The precaution of adding the water is necessary to prevent the muriatic acid mixing with the carbonic acid and altering the saturated carbonate. A straight tube is fixed to one of the mouths of F, and a syphon to the other. AliCH is the apparatus for promoting the solution of the gas produced. We see no reason why Mr. Clement's absorbing cascade might not be applied if more convenient. The apparatus used by Welter consists of a large tub full of water and several dishes, or rather small tubs placed in it upside down', and fixed, at certain distances, to each other. The gas is conveyed by means of a bent tube from the vessel, E, to A, the bottom of the tub, where it is exposed to all the pressure of the liquid in the tub. Each of these dishes lias, at one part of its circumference, a hole cut across,

that side of the dish being somewhat lower than the other, and the holes in each alternate dish are at opposite sides of the tub. In consequence of this mode of arrangement, when the lower vessel is filled with gas, it begins to escape by the hole and fills the next dish, and so on through all the others. By this means the gas is brought into contact with a large surface of the liquid, and kept so for a considerable time. These different dishes being preserved in their places by the cross piece, H, to the underneath part of which a projecting knob is attached and presses on the upper dish; a quantity of muriatic acid, diluted with an equal quantity of water, is poured into the tube, No. 2, whence it flows into E; carbonic acid is immediately disengaged, passes into the dishes, and raises the level of the solution of potass contained in the tub. Care must, therefore, be taken, in the first instance, not to put more in the tub than it will contain after receiving the gas. When carbonic acidgasisnolonger absorbed it ceases to pass over, and the acid solution remains stationary in No. 2. Let us suppose it at A—it will then be necessary to introduce into No. 2 the syphon, I, the short leg of which goes to the bottom of the vessel, F. The end of the right hand tube, D in F, ought to be lower than the level of the liquid, A, and higher than the lower part of the syphon. C. By blowing into the right hand tube the syphon is filled with the solution of muriatic acid, and it continues to flow into the syphon as long as the air in F is compressed; but in a short time it dilates, the liquid ceases to flow, and mounts one or two lines up the right hand tube. As the liquid in the tub absords the gas its level falls, and the liquid in No. 2 also descends equally. When it is on a level with the point, D, the air re-enters the right hand tube, babble after bubble, a fresh quantity of acid runs off by the syphon, and this augmented pressure causes a small, quantity of muriatic acid to flow on to the marble. Thus the muriatic acid cannot reach the marble, but as the carbonic acid is absorbed by the solution of potass, or by the liquid in the tub, and nothing is lost. This apparatus is said to work very regularly, and well; and we have thought it worth making known to our readers, as it seems a useful method for making liquids absorb gases when pressure cannot be conveniently obtained, and when the product is not required in a hurry. The apparatus wastes no time; for, after it is once set in motion, it goes on of itself till the muriatic acid is exhausted, or till the solution is saturated.

ANALYSIS OF SCIENTIFIC JOURNALS.

ANNALS OF PHILOSOPHY FOR JULY.

• . {Concluded from p. 278.)

After the biography of Gahn comes Thomas Weaver, Esq., M.R.I.A., M.R.D.S., M.W.S., M.G.S., H.M.B.I., " On the Older Red Sandstone Formation," &c. This is one of the papers which are more curious than useful. For the thousandth time, we believe, or perhaps the ten thousandth, the author remarks on that imperfection ef human nature which leads men to draw general conclusions from imperfect data; and, like all those prevx philosophers who commence with this sapient introduction, he immediately afterwards .jumps to a general conclusion (as far as we can see) not warranted by the data. The only part of the article, which is a jumble of remarks on, and quotations from, Mr. De la Beche, M. Omalius d'Halloy, Dr. Boue, Humboldt, Werner, M. Beaunier, M. Du Bosc, M. Bonnard, &c, that is at .all amusing, is the following sentence: "Continental and English geologists thus mutually assist in elucidating the positions of each other;" which means, we presume, as the researches of these gentlemen are all directed downwards, that some of them are stuck in the mud, while others are employed in holding a light to show them how to get out. But we must leave Tho

mas Weaver, Esq., with all those letters after his name, the meaning of which we cannot conjecture, to elucidate his grammatical position himself, and have only to recommend him in future to write English, though it be vulgar.

Mr. South is acknowledged to be a great calculator and astronomer, and occupies, as usual, in the present Number of the Annals, six or eight pages with his tables of correction in right ascension; which are, we have no doubt, very useful to astronomers.

This is followed by a paper " On the chemical composition of Red Silver Ore, by P. A. Von Bonsdorif, translated from the Swedish," in which the author, like a garrulous old man, details all the mistakes he committed before he accomplished his analysis. The result was, that the dark red silver ore of Andreasberg contains in 100 parts, 68.949 silver, 22.846 antimony, 16.609 sulphur, 0.289 earthy matter, 1.307 loss. Mr. Children's "Observations on the use of the Blow-pipe," we think worthy of being transcribed:—

"The blow-pipe, when skilfully handled, is the most convenient chemical instrument for mineralogical researches on a small scale, that has hitherto been invented. By its means we are enabled in a few minutes to determine the principal ingredients in any mineral submitted to our examination, even though it be composed of several elements. By merely directing the flame of a small lamp on a fragment about half the size of a pepper-corn, supported bn a piece of charcoal, or in the platina forceps, most of the volatile substances, as sulphur, arsenic, zinc, cadmium, antimony, bismuth, and tellurium, may be detected; baryta will be known by the greenish-yellow, arid strontita by the crimson colour it imparts to the llame. By employing only three fluxes, carbonate of soda, borax, and the triple phosphate of soda and ammonia (salt of phosphorus,) with the occasional use of the nitrate of cobalt, we can readily ascertain the presence of silica, alumina, magnesia, and almost all the fixed metallic oxides; and by the further examination of the fused globule, especially that with carbonate of soda, by dissolving it in a drop of muriatic or nitric acid, on a slip of glass, and applying the proper tests, unequivocal evidence may be obtained of the presence of any of the other earths or oxides of which the substance is composed, and even a tolerable estimate may frequently be formed of their respective proportions. By substituting nitrate of baryta as the flux, and using a slip of platina foil for the support, instead of the wire, the presence of either of the alkalies may, by the usual well-known processes, be detected, with equal ease and certainty, on the same minute scale of operation.

"An advantage peculiar to this microscopic chemistry is the very small quantity of matter that is sufficient for examination, which may generally be detached from rare and costly specimens without injury, whereas for operations on a larger scale, it is necessary wholly pr in great measure to destroy them. When the exact proportions of the ingredients of a mineral are required, recourse must necessarily be had to more elaborate processes, but even then previous examination by the blow-pipe is of essertial service, since, by indicating the different substances present, it enables us to determine the most advantageous method to be adopted in the subsequent analysis."

An abstract of a Report on M. Rousseau's memoir respecting a new method of measuring the power of bodies to conduct electricity, by M.M. Ampere and Dulong, as well as M. Bequerel's paper "On Electromotive Actions," &c, we have ourselves long ago passed by in the French Journals, from which they are taken, as papers nearly destitute of interest. Having occasionally attended the meeting of learned corporations, and looked into their memoirs, we came very early to the conclusion, that their

archives are the repositories for every thing dull,—for every thing that has no interest for mankind is of no utility, and cannot be sold,— and therefore it is no recommendation to a paper, that it has been, like the present two, reported on by a committee, even of the Institute of France.

C. H. Pfaff, in the next paper, shows that aqueous vapour deoxidates various substances, and supposes it possible that this fact may be applied to some practical purpose. The Annals concludes, with the exception of some scientific notices,with a very good critical paper, by Mr. Smithson; but as it refers to a geological subject never yet alluded to in the. Chemist, and touches on rather a delicate topic, "collating the revered volume with the great book of Nature," we must pass it over, by acknowledging that it displays acuteness. On the whole, we must say the Annals is somewhat improved, and seems to have felt that impulse which our scientific literature has lately received.

SELF-ACTING BLOW-PIPE.

It is pretty generally known, that bottles of Indian rubber may be expanded to a considerable size by condensing air into them; but Mr. H. B. Leeson is the first who has applied bottles so filled to the purposes of a blow-pipe. The bottles he makes use of vary in weight from a half to three-quarters of a pound, and may be readily procured at any stationer's.

"To prepare them they should be boiled in water till completely softened, which, if they are put into water already boiling, will generally be accomplished in ten minutes or a quarter of au hour. They must then be taken out and suffered to cool, when a brass tube may be fitted into the neck of the bottle, having a small cork screwed into it at one end, by which it may be connected with the condensing syringe, and to which the blow-pipe jets may be attached. There should be a milled projeetion on tlic side of the tube for the purpose of more firmly attaching the bottle to it, which may be effected by passing a ligature of waxed string round the neck of the bottle on each side of the abovementioned projection. The bottle must next be filled with condensed air. After a few strokes of the syringe, a blister will be observed to form, which will gradually enlarge till the greatest part of the bottle (which must be selected uniform in substance and free from defects) has extended to a similar substance. The condensation should not then be continued farther. Bottles of the size I have mentioned, will generally extend from 14 to 17 inches in diameter without bursting, and I have occasionally extended them much beyond these dimensions; but in this the operator must, of course, be entirely directed by his own observations. The Indian rubber varies in its quality: there is one sort which appears of a blacker hue before extension, but becomes very thin and almost transparent on condensing air into it; whilst there is another sort having a browner colour, which is much less yielding in its substance, and cannot be extended to the same thinness as the former. I have found both sorts to answer my purpose; but the above observations may be useful in determining the quantity of air which may be condensed into the bottles with safety: To apply these bottles when filled with condensed air, nothing more is necessary than to remove the syringe, and in its place to screw on a jet of such bore as may be required. On opening the cock, the air will be expelled by the elasticity of the Indian rubber, and its own condensation, in a strong and uniform stream, which, in bottles of the size I have mentioned, will continue from 25 minutes to an hour, according to the size of the jet. When once prepared, the bottles may be constantly expanded to the same size, without any danger of bursting. When the air is exhausted, the bottles will be found

somewhat larger in dimensions, but may again be contracted by holding them before a fire, or a few minutes' immersion in boiling water. This, however, is unnecessary, since no subsequent inflation will be found to increase the size of the bottle any further; and I have used the same repeatedly, without any apparent diminution of its elastic powers. The principal advantages of this blow-pipe are its great portability, and length and steadiness of action, (in which I consider it much superior to the hydraulic blow-pipe) together with the perfect liberty at which, when properly mounted, it leaves the operator's hands. This blow-pipe is applicable to any of the gases, and may, I conceive, be applied with advantage to contain the explosive mixture of oxygen and hydrogen, as no inconvenience can possibly acerue from its bursting, beyond the loss of the bottle. This blow-pipe may be supplied with air or gas during an experiment, by having a separate communication for the syringe into the piece of tube before mentioned, and this will enable the operator to continue his experiments for any period of time."*— Quarterly Journal of Science.

PREPARATION OF CAOUTCHOUC.

Mr. T. Hancock has succeeded, by seme process, the results of long investigation, but which he has not published, in working caoutchouc with great facility and readiness. It is cast, as we understand, into large ingots, or cakes, and being cut with a wet knife into leaves or sheets about one-eighth or one-tenth of an inch in thickness, can then be applied to almost any purpose for which the properties of the material render it fit. The caoutchouc thus prepared is .more flexible and adhesive than that

* Blow-pipes on this construction may be procured, very neatly and conveniently mounted, at Mr. Newman's, No. 8, Lisle-street, Leicester-square.

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