observation to another, and are besides but small, it is extremely doubtful whether, notwithstanding the care taken in adjusting the bars for examination and replacing them afterwards, they were not due to accidental derangement, when the bars were moved at the several times of observation, rather than to a tendency in the magnetism to resume a state of symmetrical distribution. Indeed it is possible that the needle made use of to determine the positions of the poles and magnetic centre may have slightly modified the magnetic state of the bar, at each observation, since it was necessary, for this purpose, to bring it within a very small distance; and such influence it is scarcely possible to prevent, especially in the case of rather soft bars, as these purposely were. The changes in the bars I., III., IV., are in general much greater from July, 1828, to July, 1829, than subsequently, and are the most indicative of the mutual action of the poles upon each other, since the changes in the positions of the more diffused poles are much greater than could have arisen from errors of adjustment or observation; but even these, admitting them to be entirely due to such action, are so small, considering the time during which they took place, that the force which produced them must have been almost evanescent as compared with the coercive force of the steel. In the bar II., the changes are extremely small from July, 1828, to July, 1829, and also from the latter date to June, 1830, and, varying much in their direction, do not indicate that they were caused by internal action; but from June to December, 1830, a decided change in the positions of the poles and magnetic centre took place. This, however, I have no doubt was entirely due to accident. When I removed this bar in December, for the purpose of making observations on it, in order to see which was the marked end, I incautiously approached a candle unfortunately placed upon a box containing a very powerful magnet, and, from the small amount of all the other changes, I have no hesitation in attributing the considerable change here observable to the action of this large magnet upon the poles of the bar. Those who have not been extensively engaged in delicate magnetical experiments can scarcely be aware of the difficulty of guarding against such accidental influence, when surrounded by apparatus which is a source of disturbance. Independent of such disturbance, there can, I think, be no doubt that the magnetism in these bars would remain very nearly, if not precisely, in the same state for almost an indefinite period. We may therefore conclude, from these observations, that, after the action of a magnet upon a bar which determines the position of its poles, has ceased, if any effect is produced by reciprocal action, the forces tending to produce this effect are almost evanescent when compared with the other forces acting upon the magnetism of the bar. Upon the whole, I am disposed to think, that into whatever state the magnetism of a steel bar may be placed by the application of a magnet to it, almost immediately after the removal of the magnet, the internal forces are in a state of equilibrium, or nearly so; and that, therefore, whatever may be the arrangement of the magnetism, it is, if not absolutely permanent, liable to scarcely any disturbance from internal action. Royal Military Academy, 27th Dec. 1830. ON THE ELECTRO-CHEMICAL DECOMPOSITION OF THE VEGETO-ALKALINE SALTS. I By W. T. BRANDE, F.R.S., PROF. CHEM. R. I. AM not aware that any experiments have been recorded in relation to the phenomena presented by the salts of the vegetable alkaline bases, when subjected to the action of voltaic electricity; and as, under such circumstances, they exhibit appearances identical with those of ordinary salts, a further analogy is thus established between those curious compounds and the other salifiable bases. Shortly after the discovery of a method of obtaining morphia in pure state, I remember that Sir Humphry Davy suggested the possibility of its affording, when electrised in contact with mercury, results corresponding with those which Berzelius had observed in respect to ammonia: he thought that the nascent elements of the morphia, as liberated by electrical decomposition, might, under such circumstances, effect a similar apparent amalgam of the mercury, and he spoke of the subject as likely to throw some light upon the corresponding ammoniacal combinations. He made, I believe, a few experiments upon the subject, but the results were not as he expected, and they were, nowhere, I believe, recorded. Since that period the subject generally has acquired much additional interest, by the discovery of several other bodies appertaining to the same class, and especially of quinia and cinchonia, the medicinal preparations of which have rendered these substances so generally known. I repeated the experiment of the electrisation of moistened morphia and mercury, a globule of which, in contact with the vegetable base, was rendered negative; feebly at first, and afterwards by a more powerful voltaic combination. The morphia, I had reason to believe, was perfectly pure; but although the process was continued for a due time, in one instance exceeding twenty minutes, I did not observe any change in the fluidity of the metal, nor did it, on being transferred to a glass of pure water, exhibit any action upon that liquid, or any appearance of having united to foreign metallic matter. Crystals of pure cinchonia reduced to powder, moistened, and subjected in the same way to the action of negatively electrified mercury, were equally inert, and exhibited no symptoms of contributing anything metallic to the mercury. When mercury was similarly electrised in contact with quinia, moistened and placed upon a positive disc of platinum, it exhibited, in the course of a few minutes, appearances very different from those exhibited with it, when electrised in contact with morphia and cinchonia; the metal became filmy, and after a time appeared to acquire a tendency to a butyraceous appearance, and evidently had its fluidity diminished. When transferred into a tall glass of distilled water, a peculiar motion was perceptible upon its surface, and ultimately some small globules of gas were liberated, and it regained, though slowly, its usual aspect. This experiment first led me to suspect that something like a metallization of the elements of the quinia had been effected, but I could not satisfy myself that it was reproduced by the action of water on the globule, nor could I, by carrying on the process of electrism for a longer time, produce a much greater effect than ensued in the first five or ten minutes. Aware of the influence which very minute quantities of foreign matter, and especially of the fixed alkalies, or of lime, might have in producing some such appearances, and more especially recollecting the singular results of Mr. Herschel's experiments upon this subject, it became important to ascertain the absolute purity of the quinia employed. I therefore examined it with this view, and found it entirely soluble in strong alcohol; when dissolved in dilute muriatic acid the solution afforded no traces whatever of lime to the usual tests; but on burning a portion of the above quinia in a platinum crucible, and dissolving the ashes in muriatic acid, traces of lime were readily recognized in the latter solution. I treated the morphia and cinchonia which I had employed in the same way, but in them no traces either of fixed alkali or of lime could in any way be discovered. I am, therefore, induced to refer all the appearances which quinia exhibits to the obstinate adhesion of a very minute quantity of lime, which I have not yet been able entirely to deprive it of. The electro-chemical decomposition of the salts of the vegeto-alkalies is very characteristic, in consequence of the difficult solubility of their bases. If, for instance, a solution of sulphate of morphia be placed in the voltaic circuit, so as to be decomposed between two plates of platinum, the negative plate, if the solution be strong, becomes presently covered with a white crust of morphia, which gradually falls off in films; if the solution be more dilute, the morphia falls in the form of a white cloud from the negative conductor. The appearances are nearly similar with the solutions of sulphate of cinchonia and of sulphate of quinia. Supposing that some more decided results than those above mentioned might be obtained by electrising mercury negatively in contact of the soluble salts of morphia, cinchonia, and quinia, the experiment was made with the respective sulphates of those alkalies, but no further appearances of metallization ensued provided the salts were pure-whereas any alkaline impurity, though in very minute quantity, gave the same equivocal appearances as had been previously obtained with quinia containing a little lime. The appearances afforded by the electro-chemical decomposition of these salts led to the question, how far the bases might be discovered by the voltaic test in the infusions of opium and bark; but when these are treated in the usual way, there is no distinct separation of difficulty soluble alkaline matter, as might have been expected, in consequence, probably, of the multiplicity of substances that are present: nor is strichnine separable in this way from the infusion of nux vomica. SOME OBSERVATIONS ON DR. ARNOTTS EXPLANATION OF THE NATURE OF STAMMERING. I BY MARSHALL HALL, M.D., F.R.S.E., &c., &c. WAS much struck, in the first instance, with the simplicity of Dr. Arnott's explanation of the defect in speech termed stammering, in his interesting and popular work, entitled 'Elements of Physics.' I, however, soon perceived its fallacy; and as this has not hitherto, I believe, been pointed out, it may not be amiss for me to do so briefly in this place. I will first copy Dr. Arnott's view in his own words. That gentleman states, that* The most common case of stuttering is not (as has been almost universally believed), where the individual has a difficulty in respect to some particular letter or articulation, by the disobedience, to the will or power of association, of the parts of the mouth which should form it, but where the spasmodic interruption occurs altogether behind or beyond the mouth, viz., in the glottis, so as to affect all the articulations equally. To a person ignorant of anatomy, and therefore knowing not what or where the glottis is, it may be sufficient explanation to say, that it is the slit or narrow opening at the top of the windpipe, by which the air passes to and from the lungs-being situated just behind the root of the tongue. It is that which is felt to close suddenly in hiccup, arresting the ingress of air, and that which closes, to prevent the egress of air from the chest of a person lifting a heavy VOL. I. *Elements of Physics, vol. ii. Part I. Appendix pp. v-viii. S |