made use of this test in a most ingenious manner, to distinguish between the two different methods of dyeing cloth with madder and with garancine. It is difficult and often impossible for calico-printers and merchants to distinguish between the two; and as the garancine dye is more fugitive than the first, and also of less intrinsic worth, it is sometimes substituted for it. There is however, a slight difference in the process of manufacture, madder-dyed goods are, in one stage of the process, passed through a solution of soap to fix the color, whilst in garancine-dyed goods the soap is replaced by hypochlorite of lime. By proceeding as follows, it is easy to distinguish between the two kinds of dye: Let camphor rotate on water in any glass vessel, as previously described, then immerse a small strip of the cloth to be tested. If the rotation stops, we infer the presence of soap, and conclude it to have been dyed with madder. But if, on plunging in the small piece of cloth, the rotation is not stopped, we then arrive at the conclusion that garancine was the dyeing material used. In like manner the purity of water may also, to a certain extent, be tested by dropping à fragment of camphor upon its surface.

CURIOUS ELECTRICAL PHENOMENA.

Prof. Tyndall publishes the following account of some curious electrical phenomena observed by Mr. R. Watson, and a party of tourists in ascending a portion of the Jung frau Mountain in Switzerland. Mr. W., in a letter to Prof. Tyndall says, On the 10th of July, 1863, I visited with a party of three, and two guides, the Col de la Jung frau. The early morning was bright, and gave promise of a fine day, but, as we approached the Col, clouds settled down upon it, and, on reaching it, we encountered so severe a storm of wind, snow, and hail, that we were unable to stay more than a few minutes. As we descended, the snow continued to fall so densely that we lost our way, and, for some time, we were wandering up the Lötsch Sattel. We had hardly discovered our mistake when a loud peal of thunder was heard, and shortly after, I observed that a strange singing sound, like that of a kettle, was issuing from my alpenstock. We halted, and, finding that all the axes and stocks emitted the same sound, stuck them into the snow. The guide from the hotel now pulled off his cap, shouting that his head burned; and his hair was seen to have a similar appearance to that which it would have presented had he been on an insulated stool, under a powerful electrical machine. We all of us experienced the sensation of pricking or burning in some part of the body, more especially in the head and face, my hair also standing on end in an uncomfortable but very amusing manner. The snow gave out a hissing, as though a heavy shower of hail were falling; the veil on the wide-awake of one of the party stood upright in the air, and on waving our hands, the singing sound issued loudly from the fingers. Whenever a peal of thunder was heard, the phenomena ceased, to be resumed before the echoes had died away. At these times, we felt shocks, more or less violent, in those portions of the body which were most affected. By one of these, my right arm was paralyzed so completely that I could neither use nor raise it for several minutes, and I suffered much pain in it at the shoulder-joint for several hours. half-past twelve, the clouds began to pass away and the phenomena

At

finally ceased, having lasted twenty-five minutes. We saw no lightning, and were puzzled at first as to whether we should be afraid or

amused.

INTERESTING ELECTRIC ILLUMINATION.

Prof. W. B. Rogers communicates to Silliman's Journal the following observations on a powerful electric illumination, exhibited in Boston, August, 1863, by Mr. Ritchie, the well-known electrician, as a part of the display attendant on a public rejoicing. The battery in question, consisting of 250 Bunsen elements, having each an acting zinc surface of about eighty-five inches, and grouped in five battalions of fifty each, was arranged in the dome of the State House; and the carbon light, and the photometric apparatus prepared for the purpose were placed in line across the same apartment, commanding a range of fifty feet. Prof. Rogers says:

In view of the immense power of the light, as observed in the previous experiment, I substituted for the 20-candle gas burner, used at that time as the standard of comparison, a unit ten times as great, formed by the flame of a kerosene lamp placed in the focus of a small parabolic reflector, and throwing its concentrated light on a photometric screen of prepared paper fixed in front of it at the distance of five feet. Before the observation, the lamp and reflector were so adjusted as to make the light cast on the near side of the screen equivalent by measure to the action of 200 candles.

This was done by the intervention of a kerosene lamp fitted up with a bridge of platinum wire for defining and restricting the height of the square flame. Such a lamp I find of frequent use in ordinary photometry, as, when suitably adjusted, it gives the light of about eight standard candles, and thus transfers the measurement in the photometer to the wider divisions of the scale. Being suspended in a balance of peculiar construction, its rate of consumption enables us to correct for any slight departure from the assigned illumination. The lamp thus regulated was placed with its flat flame twelve inches from the screen, while the lamp in the reflector was distant sixty inches, and the flame of the latter was adjusted until the effects on the screen were equalized.

A platform supporting the standard lamp and screen at the assigned distance was arranged to slide on a horizontal graduated bar, extending directly toward the carbon points so that the screen should receive the rays from the electric light and from the reflector perpendicularly on its opposite faces, In making the observations, the platform was moved to and fro until the illumination on the opposite sides of the screen was judged to be equal, and then the measured distances of the two antagonizing lights from the screen gave by easy computation their relative illuminating power.

By a series of such observations, it was found that the carbon light had a force varying from 52 to 61 times that of the lamp with reflector, making it equivalent in illuminating power to the action of from 10,000 to 12,000 standard sperm candles, pouring their light from the same distance upon the surface of the screen. This, it will be remembered, is the effect of the unaided carbon-light sending its rays equally in all directions from the luminous centre, and falls vastly short of the illuminating force of the cone of collected rays which was seen stretching,

like the tail of a comet from the surface of the great reflector. Judging from some recent experiments on the power of such a reflector to augment the intensity of the light emanating from its focus, there can be no doubt that, along the axes of the cone, when brought to its narrowest limits, the illuminating force of the carbon light as displayed on the State House could be rivalled only by that of several millions of candles shining unitedly along the same line.

In the above-described observations, a thick screen was necessary, on account of the great intensity of the lights to be antagonized. I need hardly say that the different color of the two lights added much to the difficulty of the measurements. But, by marking in each case the extreme limits on either side, it was practicable to adjust the screen pretty accurately to equality of illumination.

The only previous experiment, of precisely the same kind, which I can recall is that of Bunsen, cited in the books, which was made with a battery of forty-eight elements. In this, the photometric equivalent of the carbon light was estimated at 572 candles, or nearly twelve candles to the cell. My observations show a power more than three times as great, or about forty candles to the cell; a difference due no doubt largely to the more intensive battery at my disposal and the cumulative effect of its arrangement. I suspect, too, that the elements in Bunsen's observation were of inferior size, but on this point I am without definite information.

ELECTRICAL SUMMARY.

Electric Express.-M. Bonelli, the Italian electrician, suggests a new application of electricity for the transmission of letters, light parcels, &c. A series of coils of insulated wire are adjusted along the route, and through them runs a pair of rails upon which travels the wagon which carries the despatch-box. This wagon also carries an electric battery, and the end of the coils are so adjusted that the battery connection is made, by means of the wheels and rails, through the coil which it is just about to enter. As the wagon is of sheet-iron, it will be attracted to the centre of the coil, and the momentum which it acquires will carry it far enough to make the connection through the next coil, when the impulse is renewed.

This contrivance will make a very pretty philosophical toy, or piece of illustrative apparatus; but can it be economically applied on a practical scale?

Cosmos.

Efficacy of Lightning Conductors.-M. Quetelet, in commenting on a remarkable thunder-storm that raged over a considerable part of Belgium, in February, 1860, states that, in his statistics of the buildings or vessels struck by lightning," he found that out of a hundred and sixtyeight cases in which lightning-conductors had been struck, only twentyseven, by reason of grave defects in their formation, had failed to exercise a preservative power."

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Influence of Heat on the Voltaic Battery. M. Carlo Roberti, of Verona, in a note forwarded to the Academy of Sciences at Paris, states that, while pursuing some experimental researches with Gauss's apparatus, he was struck first with the irregularity and afterwards with the progressive periodical intensity of the pile he employed. He was soon led to attribute this to the variation of the temperature, due to the

hourly advance of a solar ray which had penetrated his laboratory. He immediately conceived the idea of applying this fact to the electric telegraph and other purposes, and states that he is now engaged in vigorous experiments, with the view of arriving at the exact numbers which establish the advantages which may be derived from the phenomena. Magnetism, Electricity, and Vegetation. — In his Physique du Globe, M. Quetelet tells us that on examining attentively the value of the monthly magnetic variation, it is found to be in direct relation with the force of vegetation. When the latter sleeps, which happens in the months of November, December, January, and February, the magnetic variation, at Brussels, is almost uniformly 5′ 28′′, or scarcely half during the period of its full activity, that is to say, from April to September, when its mean is 10′ 15′′. It reaches its plenitude in April, when the mean is 11′ 14′′, for Brussels. In another passage, M. Quetelet states, that the electricity of the air is intimately connected with the action of vegetation, and that the two phenomena have a nearly parallel march. It is not pretended that one depends on the other, but that both arise from the same cause. The quantity of atmospheric electricity at noon is much greater in winter than in summer, the relation being about 10 to 1. This augmentation of electric force proceeds in a manner almost parallel with the number of days of frost and fog, and inversely as the number of days of thunder, of elevation of temperature, of actinic power.

Terrestrial Magnetism and Temperature. — At a recent meeting of the Royal Society, the Astronomer Royal mentioned that the remarkable change which had taken place in the phenomena of terrestrial magnetism, as observed at Greenwich since 1845, was such as might be expected to take place, were the climate of the northern hemisphere to become more wintry in its character, while that of the southern hemisphere remained unaltered. It is already on record that Sir John Herschel considers the climate of the earth to be undergoing a change due to some cosmical cause. Is there any connection between his conclusions and those of the Astronomer Royal? To those who take interest in the progress of terrestrial magnetism as a science, it will be gratifying to know that Mr. Airy expresses himself decidedly in favor of long-continued simultaneous observations in various parts of the globe. With series of observations extending over many years it becomes possible to institute comparisons, to note fluctuations and disturbances, and to discover something of their laws; while short and broken series baffle investigation, and harass the inquirer to no useful purpose. - London Athenæum.

Sun-spots and Auroras. The Comptes Rendus contains a letter from M. R. Wolf to M. Remmont, in which the former says, "I find, in accordance with M. Fritz, that the frequency of solar spots corresponds exactly with that of auroras, so that we observe in the latter both the period of 114 years and the great period of 56 years, the existence of which I have demonstrated for solar spots."

Thunderstorms and the Moon. - M. Bernardin calls the attention of the Belgian Academy to the fact that many thunderstorms have occurred about the period of the new or full moon, and he invites inquiry for the purpose of ascertaining whether there is any connection between the movements of our satellite and the electrical condition of the atmosphere.

RESEARCHES IN ELECTRO-PHYSIOLOGY.

M. Matteucci has forwarded to the Academy of Sciences, at Paris, an analysis of his latest electric researches in relation to physiology, undertaken with the view of explaining one of the most remarkable yet obscure laws of the science. He began by proving that the passage of an electric current in a non-metallic body, which is, however, a conductor of electricity on account of the liquid which it has imbibed, acquires the property termed secondary polarity. By virtue of this property, if it be touched by the homogeneous ends of the galvanometer, it is found that this body is traversed by an electric current, directed in a way opposite to the voltaic current which has excited the polarity. Such is the case with a cotton wick moistened with water, a vegetable stem, a membrane, and a nerve, independently of its vitality. Among these different bodies a nerve is remarkable by the rapidity with which it is polarized in all its points, and by the intensity of its polarity.

Electricity of the Circulation of the Blood. M. Scoutetten has reported to the Academy of Sciences at Paris an account of some experiments made upon horses which were previously made insensible to pain. He found that the electric positive sign, indicating the direction of the current, was constantly from the red, or arterial, to the black, or venous, blood. He concludes his memoir by saying that since it is demonstrated that the red blood and the black blood, in their contact through the walls of the vessels, which act as true porous vases, give stated electric reactions to the galvanometer, we must admit, that as all the parts of our body are traversed by sanguineous fluids, there must necessarily be a constant disengagement of electricity in the most relaxed tissues of our bodies. Thus each organic molecule is incessantly stimulated by the electric fluid, and thus under the influence of this excitement, all the functions of the body are performed. The oxygen contained in the red blood burns up the organie molecules with which it is in contact, and produces heat, without which life is impossible. Under the influence of electricity is effected, during digestion, the selection of the nutritive molecules and their assimilation. The same action takes place in respiration and in all the other functions. These facts perfectly agree with the electric phenomena of combustion. The carbon takes the negative electricity and the surrounding air the positive, or rather, the current is established between the carbon and the oxygen of the air. Now, the principal action of the red blood, by reason of the oxygen in it, is the producing a true combustion in our tissues.

Electric Conductivity of Muscle. — Ranke, a German physiologist, has published, among the results of his investigations into the phenomena of electric currents in the living muscle, the fact that dead muscle is a much better conductor of electricity than living muscle, because of the presence of certain products of decomposition which do not appear till after death. He concludes, further, that the conducting power of living muscle is three million times weaker than that of mercury, and one hundred and fifteen million times below that of copper.

ELECTRICITY BY FRICTION AND BY CONTACT DERIVED FROM ONE SOURCE.

H. Buff (Ann. der Chem. u. Pharm. Vol. 114) says: For electricity to be evolved by friction, it is essential that the two surfaces which are