From the temperature of 0° to about 25°, the changes in volume are nearly proportional to the temperature; at 35° is the maximum of volume; above 35° a rapid contraction comes on, which gradually diminishes to about 55°, when a change in the curve indicates the minimum volume. Dilatation then commences slowly, but gradually increases to 75°, when the metal fuzes; between 75° and 80°, the dilatation is considerable, but afterwards becomes the same as that observed before the irregularities commenced, i. e. between 0° and 35. Calculating backwards, from 80° to 0° upon the dilatation given above 80°, it gives the same volume for the metal as is obtained by actual observation; so that it may be concluded the oscillation of volume between 35° and 75° has no influence upon the final volume after liquefaction. One very singular fact is, that the volume at the liquifying point is the same with the maximum occuring at the 35th degree. The anomaly in the expansion of the solid alloy may be observed in the following manner:-Blow a thermometer bulb in the middle of a tube heat it to 60°; then fill it with the fuzed alloy, by dipping one end in, and drawing out the air with the mouth at the other. Allow the whole to cool very gradually. Some time after the solidification of the metal, the tube will be seen to be broken to pieces by a number of small cracks. By allowing all this to take place in water, the temperature, when the glass broke, was found to be 40. This is explained, if it be considered that at 75° the metal became solid; and that after contracting, it would at 35° resume the bulk it had at 75°; but considering the contraction of the glass between 75° and 35°, it is evident that, as the temperature approached the latter, the diameter of the metallic mass would be greater than that of the glass vessel containing it, and would consequently cause its fracture. The dilatation of phosphorus was observed between 0° and 70°, in a similar manner as with the alloy. The results were, that solid phosphorus expanded in proportion to the temperature, with the exception of a few irregularities, probably due to imperfect observation; that liquefaction produced a sudden expansion, independent of temperature; that liquid phosphorus dilates much more rapidly than solid phosphorus; but that the dilatation is sensibly in proportion to the temperature. Comparative Table as to Water, the Alloy, and Phosphorus. !..WATER. cation. ALLOY. 1. Dilates by solidification. 1. Condenses by solidifi2. Expansion greater after congelation than before. 18. Minimum of volume -- whilst liquid. 4. The volumes of liquid which would be indicated by a supposed continuance of the dialatation of the solid are.. greater than those given by observation. 2. Expansion equal before 3. 4. The volumes of liquid here indicated in a similar way, are the same as those given by observation. The volumes of liquid here indicated in a similar way, are less than those given by observa20595tkation, ¡qua (dol, qua872. The results of 2 and 4 strikingly support the atomic theory of dilatation. If the change in volume of a body for a unit of temperature is directly as some whole power of the distance of the molecules, then one consequence would be, the impossibility of equality between the successive changes of volumes. There is nothing, however, which leads us to suppose that the second differences of the volumes may not be so small as to escape observation, between such brief limits as those bounding the experiments. But if, by any cause, a sudden change of volume, independent of temperature, occurs, the theory: requires that the increments of volume by change of temperature, before and after this sudden change in bulk, should differ; and this the comparison above confirms. Looking at 2 and 4, it will be seen that liquid phosphorus dilates more than solid phosphorus; and also that by liquefaction the volume is increased. Dismissing the oscillation in the volume of the alloy between 35° and 75°, which probably depends upon other causes than temperature, the expansion is equal before and after liquefaction, which corresponds with the theoretical conclusion (4). Again, the expansion of water is greater than that. of ice; and the volumes acquired by change of state are in the sense required by theory. It will be highly interesting to ascertain whether, for other bodies also, the greatest expansibility is always for that state in which the greatest volume is acquired.-Ann. de Chimie, xl. 197. 2. On the Shock felt by Animals on the cessation of an Electric Current passing through them.-The peculiar sensation felt by animals when they cease to form the communication between the poles of a voltaic pile, and several other physiological facts produced by electricity, have been carefully examined by M. Marianini, in a memoir first read to the Académie de Roveredo. The conclusions which he has himself drawn from his researches are as follows:— i. The received principles of the voltaic pile do not authorise the conclusion that there is any reflux of electricity in it at the moment of interrupting the circuit. ii. Though such a reflux should take place, the shock felt by the animal, on ceasing to form part of the circuit, could not be attributed to it. iii. The two kinds of contractions produced in muscles by electricity, namely, the idiopathic and the sympathetic, require to be distinguished from each other in this: that the first take place, whatever be the direction in which the current-penetrates the muscles; and the second only when the current per-: vades the nerves in the direction of their ramifications. iv. The agitation felt by animals when they cease to form part of the voltaic circuit is occasioned by the electricity, when it moves through the nerves in a direction the contrary of their ramifications, producing a shock at the instant when it ceases to penetrate, and not when the circulation is established. v. When the electric fluid penetrates the nerves in a contrary direction to their ramification, instead of occasioning a contraction, it produces a sensation. vi. An animal feels a sensation at the moment when an electric current, which runs through the nerves in the direction of their ramification, is interrupted.Ann. de Chimie, xl. 225. 3. Conductibility conferred by Water.-In the second volume of this series, p. 465, we noticed the curious fact observed by M. de la Rive, that a fluid (bromine) having no conducting powers for electricity, was competent, when taken into solution by water, very much to increase the conducting powers of the latter. M. de la Rive has added another to the curious facts of that kind there referred to. Fluid sulphurous acid he finds to be a substance which does not conduct voltaic electricity. The platina wire of the voltaic pile, when plunged into it, allowed of no transference of electricity from one to the other; but so soon as a little water was added to the acid, then the current passed, and action immediately appeared. The sulphur of the acid, and the hydrogen of the water, went to the negative pole, and the oxygen of both to the positive pole; and the galvanometer was now influenced by the current, which passed through it in the ordinary manner. -Bib. Univ. xl. 205. 4. Conducting Power of Mercury in the Fluid and Solid State.-The intense cold produced by the free evaporation of liquid sulphurous acid is such, that a portion of mercury, equal to the size of a small nut, is readily frozen by it even in the open atmosphere, andTM retained in that state for several minutes. M. de la Rive has taken advantage of this process to institute a comparison between the conducting powers of mercury for electricity in the fluid and in the solid state. Two similar globules were placed each between two points of platina, and their exactly equal conducting power ascertained by a double galvanometer: all being then arranged so that the current of electricity experimented with should be divided equally between them, one of them was frozen by sulphurous acid, when it immediately became a better conductor than before. It appeared, therefore, that the congelation of the mercury very sensibly augmented its conducting power; and M. de la Rive asks whether this phenomenon may not be connected with the contraction which the metal is known to undergo at the moment of solidification-Bull. Univ. xl. 203.1 Query. How much of the effect may be due to the mere depression of temperature of the mercury and neighbouring platina wires, which Sir H. Davy has shewn increases the conducting power of all the metals, even without change of state?-ED. 1 5. Coloured Blow-pipe Flame; its use as a Test, bý M. Buzengeiger. This test depends upon the colour given to the blue part of a blow-pipe flame by the introduction of different substances. It is necessary that the conical blue flame, and the blue vapour surrounding it, should be distinctly seen; for which purpose the wick is to be cut obliquely, the higher part placed on the right hand, and the wick divided for the stream of air from the point of the blowpipe. The oil used should be such as has not been purified by sul phuric acid, for then it always retains a little acid, and chars the cotton. The wick should be of unbleached cotton: that which is bleached often contains a little lime, which affects the colour of the flame. The experiments are best made out of ordinary day-light. The piece of substance to be tried should be supported in platina forceps; and the blue flame being well defined, it should be introduced from below, upwards, into the external vapour just before the blue point. The form of the fragment may be wedge-shaped, acicular, or scaly. If the matter be in powder, it may be mixed into a paste in the hand, extended on charcoal, moulded into form, and then dried by a sufficient heat. When the trial piece is first introduced into the blue vapour, the latter immediately becomes of a reddish yellow colour, varying with the substance; this gradually diminishes and disappears, and then the blue vapour which bathes the body is either unaltered and scarcely visible, or else it acquires a colour according to the nature of the substance exposed to its action. HOC to Three substances produce a red colour: strontia, lime, and lithia. Carbonate and sulphate of strontia both produce it. The mixture of baryta makes the colour disappear. Lime gives a less intense colour than strontia. Impure limestones and dolomites produce little or no colour; fluorspar, an intense colour; the sulphate, a feeble colour; the phosphate and borate none. Lithia produced a fine purple red colour, which soon disappeared; petalite produced a very feeble tint. Blue colours are produced by arsenic, antimony, and lead. Green colours are produced by boracic acid, baryta, and oxide of copper. Pure boracic acid yields a fine green. Borate of lime, datholite, and botryolite, produce a paler green. Borax gives a red atmosphere, unless it be first moistened with sulphuric acid. The addition of Turner's flux was not found to increase the effect, the substances giving it as well without. All barytic minerals colour the flame green. Most of the copper minerals gave a fine green colour, even though only a small quantity of copper was present. Plumbiferous minerals, containing a little copper, gave a blue flame with A green extremity. Ann, des Mines, v. 36. ༄་།། 6. Gas-burners-The effects produced upon an Argand gas flame, by varying the size of the air and gas apertures, the form of the glass, &c. is well known, but it is not so well known that the method which gives apparently the brightest light is not always that which really gives the most light for a given volume of gas consumed. From various trials, always made in reference to the quantity of gas burnt, Mr. Lowry concludes that the greatest effect was produced when the holes were numerous, and rather large than small, the central aperture narrow, and the glass near the flame; the outer aperture being in such proportion to the inner as to keep the flame cylindrical. This construction, however, when carried to the extreme, is attended with some practical disadvantages. B Burners being, often placed in exposed situations, the least motion of the air brings the flame in contact with the glass in such a way as to pro duce smoke, and the glass being intensely heated is more liable to be broken. I found it answered the purpose fully as well to enlarge the air aperture, making the glass chimney rather wider and shorter, reducing, in this manner, the speed of the air through it. Experience has shewn, at Dumfries and elsewhere, that such burners answer the purpose of requiring less gas than other burners, and giving at the same time as brilliant, and perhaps a more beautiful flame.Phil. Mag. N. S. v. 375. 7. Preparation of Compounds of Chlorine at Low Temperatures. Considering the change of form and condensation which occurs when chlorine and water are in contact at temperatures below 40° Fahrenheit, M. Coulier was induced to arrange his apparatus for the preparation of certain chlorine solutions, so that in winter the vessels should be exposed to the air; and he states that, by attention to this particular point of temperature, great advantages are obtained. This must evidently, also, be the case in the manufacture of chloride of lime, or bleaching powder; and, though the combinations of the chlorine itself tend to raise the temperature, yet still many degrees 'would, in most cases, be found entirely under command. bos 8. On Boyle's Fuming Liquor.-The theory of the formation of this well-known substance has recently been examined by M. Gay Lussac. Two parts of sal-ammoniac, two parts of anhydrous lime, and one part of sulphur, produced no azote when distilled together, but evolved at first pure ammonia, and then hydrosulphuret of ammonia in white crystals, which ultimately dissolved in the fuming liquid product. The residue in the retort consisted of chloride and sulphuret of calcium, and sulphate of lime. No hyposulphate or sulphate of lime was or could be present, as a dull red heat had been applied. Hence it is evident that the ammonia had given up no part of its hydrogen to the sulphur; no azoturet of calcium had been formed. A The hydrogen necessary may be given either by the muriatic acid, or by the water formed by its hydrogen with the oxygen of the lime: the former supposition is the most natural, but at the same time it can be shewn that water does, in certain circumstances, render up hydrogen in the production of Boyle's fuming liquor; for, on using the sulphate or phosphate of ammonia in place of the muriate, the same substance is obtained, and without the disengagement of azote."9 still more direct proof is, that, on adding water and sulphur to the sulphuret of calcium, and distilling, sulphuretted hydrogen was obtained: again, by heating moistened sulphuret of barium, or passing steam over the ignited sulphuret, sulphuretted hydrogen was again obtained. This is, because that sulphuret contains three proportions of sulphur, whereas the sulphuret of calcium contains only two, and therefore requires an extra addition of sulphur. From all these facts, it is evident that, in preparing Boyle's fuming liquor, one part of the sulphuretted' hydrogen is produced by the |