become magnetic. The temperature of my air-thermometer having become constant, I closed it by a small drop of alcohol in a glass tube of 1 mm. bore (04 inch). When the magnetism was excited by a Grove's battery of 12 elements, the drop of alcohol was seen to be repelled outwards about 3 mm. (-12 in.) and to return even more rapidly to its former position upon the interruption of the current."

Comptes Rendus de l'Acad. des Sciences, Feb. 7th, 1848, p. 237.

Experiment with the Electric Telegraph.

Translated for the Journal of the Franklin Institute.

M. Dujardin of Lille, communicated to the Academy, the result of an experiment upon Electric telegraphing which he performed be. tween Lille and Amièns, on the 25th January last. The telegraph was worked without a battery, by means of a magneto-electrical machine with vibrating armature, composed of three magnets. The experiment succeeded completely. During the course of the experiments, which lasted an hour and a half, but one of the magnets was employed, the whole power of the machine having been found much too great. Ibid. 14th Feb., p. 239.

On the Colored Photographic Image of the Solar Spectrum. By M. EDMOND Becquerel.

The author in the course of his researches upon the chemical action of light was led to this remarkable fact, that the solar spectrum could form its image with colors corresponding to its own, upon a plate of silver properly prepared. For this purpose the plate may be attacked by free chlorine with the precautions indicated in the note presented to the Academy: the sensitive coating which is formed. upon the surface of the plate, is red in the prismatic red, yellow in the yellow, green in the green, blue in the blue, and violet in the violet. The reddish tint turns to purple in the extreme red, and extends even beyond Fraunhofer's line A; as to the violet it continues far beyond A, gradually becoming more feeble. When the action of the spectrum is permitted to last a long time, the tints become dark, and the image finally takes the metallic lustre; the colors have then disappeared.

According to the preparation of the plate and the thickness of the sensitive coating, any one of the tints of the spectrum may be made to predominate; thus a surface well prepared and previously in diffused light colored purple under a deep red glass, gives a beautiful colored photographic image of the spectrum, in which the orange, yellow, The green, and the blue, are marked with the greatness clearness. The substance formed upon the surface of the silver is not the white chloride but probably a sub-chloride, since it is not strongly colored beyond the visible violet, as the chemically precipitated chloride is, and the maximum of action is found in the yellow, where the maximum of luminous intensity is, or moves towards the red, according to the preparation to the plate. To get a tolerably rapid action, it is neces

sary to use a strongly concentrated spectrum. These effects explain the red color of the chloride of silver, and of the sensitive paper formed with that compound, in the red rays, which has been already observed by MM. Seebeck and Herschel.

The author has succeeded in preparing by means of free chlorine, and also by using bichloride of copper, a sensitive coating of the chloride of silver so impressed that now only certain parts of the spectrum are represented with their colors, but besides, white light makes a white impression.

The compound formed upon the surface of the silver, by the action of chlorine, is the only one hitherto found which shows the properties here mentioned. Up to the present time, it appears necessary to keep the colored prismatic image in the dark, and the author has not found the means of fixing it under the influence of light. If the fixation could be accomplished, and if the sensitiveness of the material was greater, we could not only draw but also paint by light; nevertheless the results mentioned show that the solution of the problem is possible. Ibid, 7th Feb., 1848, p. 181.

New Liquid for Lamps.

In a letter from M. Louyet, of Brussels, read to the Academy of Sciences of Paris, by M. Pelouze, he states that he has satisfied himself by experiment that the essential oil obtained by the distillation of common resin, when burned in the camphene lamp equals if it does not surpass the camphene itself. He does not say whether in light or in smoke. But the fact reminds us of similar experiments made in this city some years ago by one of our most distinguished chemists for the purpose of ascertaining whether certain products obtained by the distillation of gas tar could not be substituted for camphene. It was found that the substance burned beautifully, the only drawback being, that nobody could stay in the room with it owing to the smell. M. Louyet attributes the invention of the lamp for burning camphene to the English under the name of the Vesta Lamp. The Vesta Lamp was nothing more than the ordinary camphene lamp which had been used and patented in this country years before.

Description of an improved Wiring Machine for the manufacture of Tin, Sheet-Iron, and other Plate Wure, Patented by A. W. WHITNEY, Woodstock, Vermont, 1847.

The face plates or rolls H H, are made of cast-steel of an improved form having the journal boxes of their shafts in a cast-iron frame. This frame consists of two pieces, fitted together at A, and at the top of the upright piece under K. The journal box A has two projecting ears or bearings, (one of which is seen at A,) at right angles to the shaft B H, on which ears it is supported, forming a fulcrum to the shaft BH; thus preserving the bearing of the shaft A perfect, while the end H is raised and depressed in the process of working. B is a movable

collar for adjusting the shaft and rolls longitudinally, with great nicety. C is a binding screw, for keeping the collar in place. In the shaft concealed by the collar B, is a spiral groove, into which the binding screw euters. Thus, by turning the collar on the shaft, a nice longitudinal adjustment can readily be obtained. The movement of the rolls H H, is secured in the usual manner by the connecting gearing G G. Fis a gauge extending between the rolls, with a spring F, and a thumb nut L, for adjustment. I is a forming gauge, consisting of a friction roll, attached to the side of a short rod or shaft, and having its journal bearing in the frame. On the inner end of this shaft is a ratchet wheel N, for placing the gauge in any desired position. Fitted to the ratchet is a latch E for holding it in place. At D is a spring, pressing the latch into the teeth of the ratchet.

In the working of the machine, the bearing at A always remains perfect; for its journal box, by turning on its ears, accommodates itself to the shaft in all positions. Again, the inclination of the shaft BH is always towards H, so as to bring the collar B in contact with the box. Now, to compensate for any wear which may displace the rolls H H, as well as to adjust them to different kinds of work, the collar B is always immediately adequate.

It will readily be seen that the above improvements secure advantages, not possessed by any former construction, rendering the machine susceptible of immediate adaptation to plates of different thickness. The above improvements are applied to other machines.

On the Curiosities of Glass Manufacture. By MR. A. PELLATT. This communication would have been made on the Friday before, but for an alarm of fire in the Theatre of the Institution. On the present evening, as it was not considered prudent to re-erect the furnace which had caused the apprehension, Mr. Pellatt explained the various processes by diagrams, models, and working instruments. Of these processes we can give but a brief outline. It was noticed that in ancient, as in modern glass, sand was the base, and alkali the solvent,

and the injury occasioned to the glass by an excess of the latter ingre, dient was pointed out. That opacity of glass, called devitrification was explained as consisting in the formation of a multitude of minute crystals in close contact with each other on the surface of the glass. The process of annealing was then described; and it was shown that a glass tube forty inches in length contracts if annealed, a quarter of an inch, while an unannealed tube of the same length contracts but one eighth of an inch. The most interesting part of Mr. Pellatt's discourse referred to the mode of making Vitro di Trino, and of impressing heraldic devices, &c., on glass. In the case of Vitro di Trino, the gathered glass, after being expanded into a bulb or cylinder of the required size, has rods of other glass or enamel attached to it in a vertical position, at equal distances all round, and then, the bottom being held, the top part is more or less turned, so as to give an equally inclined twist to the vessel and the rods. A similar but larger vessel is made, but which is also turned inside out, and then the former is put into the lathe; and, being expanded by blowing, the two come together and adhere by the rods and their intersections, but enclose small portions of air, which, being regular in size, form and disposition, give the character of the glass. When heraldic devices, &c., are to be impressed, a mould of the design is made in a fit earthy material, (being puzzolana or one of the volcanic deposits,) and this is placed within, and forms part of the larger iron mould in which the decanter is blownwhen the large mould is removed, the earthen portion still adheres to the glass, and continues in its place until the bottle is finished. After the annealing, the mould is moistened with water, and immediately separates, and the impression is found really perfect.

At the close of Mr. Pellatt's communication, Mr. Faraday called the attention of the members to two circumstances of philosophical interest, which had happened during the momentary apprehension of fire to which we have alluded.-1. At three different times the water poured on the cinders of the temporary furnace, when, on the fire being drawn, they fell on the hearth, became decomposed by the ignited carbon; and the hydrogen, driven by the sudden expansion of steam, &c., having penetrated the hot and porous hearth stone, found its way to the heated beams and space which were immediately beneath.-2. This gas, though not in the state of flame as it passed through the hearth-stone and pugging, was, after being mixed with the air below, sufficiently hot to enter into combustion,-producing three gushes of flame downwards from beneath the hearth:-and it was experimentally shown that a temperature so low as barely to scorch paper, and in which the hand may be held for some seconds without inconvenience, is yet able to ignite a jet of coal or hydrogen gas in air.-Proc. Roy. Inst.

Origin of the Plague.

Athenæum.

In ancient Egypt the plague was unknown. Although densely populated, the health of the inhabitants was preserved by strict atten

tion to sanitary regulations. But with time came on change-and that change was in man. The serene climate, the enriching river, the fruitful soil remained; but when the experience of 2000 years was set at nought, when the precautions previously adopted for preserving the soil from accumulated impurities were neglected,-when the sepulchral rites of civilized Egypt were exchanged for the modern but barbarous practices of interment,-when the land of mummies became, as it now is, one vast charnel-house-the seed which was sown brought forth its bitter fruit, and from dangerous innovations came the most deadly pestilence. The plague first appeared in Egypt in the year 542, two hundred years after the change had been made from the ancient to the modern mode of sepulture; and every one at all acquainted with the actual condition of Egypt, will at once recognize in the soil, more than sufficient to account for the dreadful malady which con stantly afflicts the people. -Mr. Walker on the Metropolitan Grave Yards. Ibid.

On the Electro-Bronzing of Metals.

MM. Brunel, Bessin, and Gaugin presented to the Academie des Sciences, at Paris, specimens of metals bronzed by electro chemical means. M. de Ruolz, in 1841, cominunicated to the academy a process for bronzing metals, by depositing upon them, by the aid of the galvanic battery, layers, more or less thick, of brass or of bronze. This process, which required the employment of the double alkaline. cyanides of copper and zinc, or of copper and tin, was not adopted in practice, on account of the great expense of the cyanides, and for other reasons. MM. Brunel, Bessin, and Gaugin, have substituted for the cyanides, a solution in water, of 500 parts of carbonate of potash; 23 chloride of copper; 40 sulphate of zinc; and 250 nitrate of ammonia. To produce bronze, a salt of tin is substituted for the sulphate of zinc. By means of these solutions of brass or of bronze, a coating can be given to cast or wrought-iron, steel, lead, zinc, tin, and alloys of these metals, with one another, or with bismuth and antimony, after a previous cleaning according to the nature of the metal. The operation is conducted with a cold solution. The metal to be coated is placed in connexion with the negative pole of a Bunsen battery, a plate of brass or of bronze being employed at the positive pole. When the objects have been covered with a coating of the metal desired, and have received their proper color, they will be found to rival the finest bronze. Civ. Eng. & Arc. Jour.

Sulphate of Iron for Purifying Gas.

M. Marens, of the University of Louvain, has made a discovery in the use of sulphate of iron for the purification of coal gas. By this arrangement, the gas passes through two purifiers: in the first is placed 1 cwt. of sulphate of iron, dissolved in 83 gallons of water, and in the second milk of lime, made by adding 83 gallons of lime to