and whether or not they be similar to those obtained in treating the infusion. c. Extract. 1. The same quantity of bark, root, or plant, coarsely powdered, is to be subjected to the action of boiling water several successive times. 'The different decoctions added together are to be slowly evaporated in large vessels, to the consistence of extract. The extract to be weighed, the colour, taste, &c. noted. 2. Ascertain how much of the extract is dissolved in alcohol. Mark the taste, colour, and smell of the resulting tincture. 3. Test the tincture by a. Distilled water. b. Emetine, gelatine, litmus, and turmeric paper, oxalic acid, carbonate of potash; and write down the result. c. Sulphate of iron. d. Nitrate of barytes. g. Prussiate of potash. 5. If any residuum be left after treating the extract with alcohol, subject it to the action of distilled water, exposing it to a gentle heat at the same time, and trying the solution, if any with the above tests. d. Alcoholic Infusion. 1. A given weight of the bark, root, &c. coarsely powdered, is to be infused into a known quantity of alcohol for a given number of days. 2. The smell, colour, taste, perfume, &c. of the resulting infusion are to be noted. 3 The infusion to be tested with a. Distilled water. b. Gallic Acid. c. Sulphate of Iron. 4. The residuum, after filtering the alcoholic infusion, is to be weighed and examined. e. Distilled Tincture. 1. The alcoholic solution should be next distilled in a glass retort. 2. Observe whatever phenomena may occur during the distillation. 3. The result of the distillation should be tested with a. Distilled water. b. Prussiate of potash. c. Sulphate of iron. 4. Dry the residuum; weigh it, note its colour and consistency, and whether it attracts moisture. 5. Is it soluble in water? 6. Is it soluble in alcohol, æther, oil of turpentine, caustic, alkaline solution? 7 In either case, try the solution with the usual reagents. Description of Brooke's or Newman's Blow-pipe. By Mr. CHILDREN.* BROOKE'S, or Newman's Blow-pipe, although not calculated for mineralogical experiments, in others is highly useful. Indeed, when used with atmospheric air, it may be applied to all mineralogical purposes, though still with less advantage than the common blow-pipe in skilful hands. But when filled with a condensed mixture of oxygen and hodrogen gases in the proportion requisite to * From Berzelius on the Blow-pipe, translated from the French, by J. G. Children. form water, one essential character, the fusibility or infusibility of different substances as determined by the common blow-pipe, disappears before the intense heat produced by this, which levels all bodies to one general class of fusible substances; though very evident differences are still observable in the facility with which different bodies are reduced to the state of fusion. In return too for the character which is thus lost, we gain a new one in the appearance of the otherwise infusible body after it has been melted. This apparatus was first made at the desire of Mr. Brooke, by Mr. Newman of Lisle-street. An accident that occurred to Dr. Clarke, by the explosion of the reservoir, occasioned several attempts at its improvement. The most perfect of which is represented in Plate III. fig. 4. It was suggested by Mr. Professor Cumming, of Cambridge. a, fig. 1, is the reservoir made of sheet copper, 5 inches long, 3 inches wide, and 3 inches high; b, a syringe connected by a couple of stop-cocks, c, to the reservoir; d, is the head of the trough (or safety apparatus) fitting in its place by a screw, perfectly air tight: the trough is inserted in the reservoir in the direction of the dotted lines, and descends to the bottom: it is represented on a large scale at fig. 4; e, a stop-cock proceeding from the head d, and f, its jet fixed to it by the ball and socket joint, g. When the instrument is used, its parts are to be put together as in fig 1, and the reservoir exhausted by working the piston of the syringe b. The stop-cocks must then be closed, the syringe with the upper stop-cock taken off, and the syringe alone placed in the upright position shewn at fig. 2. The bladder, h, containing the gases, must then be connected by the screw socket, k, and its stop-cock with the syringe. The syringe stop-cocks are now to be opened, when the gases will issue from the bladder, and fill the reservoir. The head of the trough is then to be unscrewed by the key, (fig. 3), and oil poured in, to about half an inch above the lower screen of wire gauze (see fig. 4.) and the head again screwed tight in its place. The gases are next to be condensed into the reservoir, by working the piston of the syringe as before, and all the stop-cocks being now shut, the apparatus is ready for use. During the whole time the jet is burning, the oil will be heard to play in the trough. If the current be inflamed, and the instrument abandoned to itself, the jet will go on burning until the expansive force of the at mosphere within the box is no longer sufficient to propel a stream with the required rapidity through the tube; at this time the inflammation will pass backwards, unless the tube be very fine, and will fire the small quantity of mixture in the upper part of the trough, and then its effects will cease, the atmosphere in the reservoir remaining as before. When, however, the regular use of the instrument is required, it is better to shut the jet-cock before the atmosphere is quite out, and condense in a fresh portion of gas. Attention should be paid to the quantity of oil in the trough it should cover the gauze, but not to too great a height; if there be too much oil, it is possible that the agitation caused by the passage of the gas through it, may throw a drop or two through the gauze above, against the inner orifice of the jet tube, which would cause a sputtering in the flame. The oil should be emptied out from the trough when the apparatus is laid by. Fig. 4 is a section of the trough and part of the reservoir drawn, on a large scale, in order to render its construction more distinct. A.A.A. is the reservoir. B.B. a brass tube (the trough) closed at the bottom, and fixed air-tight into the reservoir. C. is a small tube in the interior of the reservoir; its upper orifice is covered with fine wire gauze, and reaches nearly to the top of the reservoir; its lower orifice is inserted into the bottom of the trough; four holes are made from the trough into the tube, and open a communication to the gases in the reservoir; a circular flat valve, D, lined with oiled silk or leather, and moveable on a central pin, E, covers these holes, and prevents the passage of any thing from the trough into the reservoir. F, a fine wire gauze intersecting the trough. The head of the trough (d. Fig. 1.) contains a small chamber, G, communicating by a fine tube with the interior of the trough, just below the orifice of which is a second piece of very fine wire gauze, M. The stop-cock, H. connects the head with the jet, having a circular motion by the ball and socket joint, I, to which various tubes, as K, may be adapted. The line at L, marks the height to which the oil should rise in the trough. For further security, Mr. Newman informs me that he puts several pieces, to the number of twenty or thirty, of very fine wire gauze between the stop cock, H. and the ball and socket joint, I, and the end of the reservoir, nearest the syringe, is made weaker than any other part, so that if an explosion should happen in the reservoir, it will yield in that part rather than any other. With these precautions, the instrument may be considered, provided there be no fault in its construction, and every thing in good order, perfectly secure. Lino Stereo Tablets. WE did not expect to have occasion to speak of Mr. STEART'S Lino-Stereo-Tablets again, farther than to in |