MANUFACTURE OF LEATHER IN RUSSIA.

From this extensive paper it appears that the matters chiefly used in tanning are the bark of the oak, containing from 6.04 to 4.37 per cent. of tannin according to the season, that of willows, of the elm, and the birch. The leaves of the arbutus, employed in the governments of Kasan, Viatka, and Perm, contain about 16 per cent. of tannin, while the root of wild sorrel (Rumex acetosella) contains 12 per cent. For removing the hair from hides, a lye made from wood ashes is still employed. The softening of the leather is effected by means of the excrement of dogs, which acts on the leather by means of the biliary acid present, which forms with soda a kind of soap. After tanning, white Russia leather is coated with a mixture of tar and seal oil. Black Russia leather is dyed with alum, extract of sanders, and ferrous sulphate. Horse hides are tanned to a great extent for sole leather.—M. Ryloff.

IMPURITIES IN PHOTOGRAPHIC CHEMICALS, AND TESTS FOR SAME.

[Table referred to in a paper read before the Birmingham Photographic Society by G.M. JONES, M.P.S.]

SUBSTANCE.	IMPURITIES POSSIBLY PRESENT.	TESTS.
Ammonia, NH₃ Molec. Wt. 17	Carbonic acid	Renders lime-water milky.
	Dissolved solid matter	Residue left on evaporation.
	Chlorides	After acidulating with nitric acid, it gives a precipitate with silver nitrate, which after washing is readily soluble in ammonia and reprecipitated by nitric acid.
	Sulphates	After acidulating with nitric acid, it gives a precipitate with barium nitrate.
	Lime	A white precipitate with oxalate of ammonium.
	Lead is often present, derived from the action upon flint glass bottles	Black precipitate with sulphureted hydrogen.
Nitric acid, H, NO₃ Molec. Wt. 63	Traces of sulphuric acid	After dilution it gives a precipitate with barium nitrate.
	Chlorides	After dilution it gives a precipitate with silver nitrate.
	Peroxide of nitrogen	The acid is yellow.
	Iodine may be present if the acid be prepared from sodium nitrate.	After dilution and cooling it gives a blue color with starch, paste, or mucilage.
Hydrochloric acid, HCl Molec. Wt. 36.5	Free chlorine	Liberates iodine from solution of potassium iodide. See also "Chlorides," nitric acid.
	Sulphuric acid	As above for nitric acid.
	Perchloride of iron	Yellow color. Brown precipitate with ammonia added till it smells slightly.
Sulphuric acid, H₂SO₄ Molec. Wt. 98	Bisulphate of potassium	Residue on evaporation.
Sulphuric acid, H₂SO₄ Molec. Wt. 98	Sulphate of lead	Milkiness on dilution. May be completely freed from lead by diluting with three or four times as much water, and allowing to settle.
Acetic acid (glacial), H C₂H₃O₂ Molec. Wt. 60	Water	Does not solidify when cooled to 17° C. (53º F.)
	Sulphurous and hydrochloric acids	White precipitates with silver nitrate.
	Aldehyde, or volatile tarry matter	Blackens in the light after adding silver nitrate.
	Organic sulphuric acid	Smell of garlic.
Citric acid, H₃C₆ H₅O₇H₂O Molec. Wt. 210	Tartaric acid	Strong solution of potassium. Acetate added to a strong solution of the acid will deposit whitecrystalline bitartrate.
Pyrogallic acid, (C₆H₃)HO₃ Molec. Wt. 126	Metagallic acid	Black residue, insoluble in water.
Silver nitrate, AgNO₃ Molec. Wt. 170	Free nitric acid	Reddens litmus paper. (Neutral silver nitrate does not affect litmus.)
Potassium carbonate, K₂CO₃ Molec. Wt. 138	Chlorides and sulphates	Same as for ammonia.
Potassium iodide, KI Molec. Wt. 166	Potassium carbonate	A strong solution is alkaline to test paper.
	Sulphates and chlorides	Same as for ammonia.
	Potassium iodate	A pretty strong solution becomes yellow from liberation of iodine on addition of dilute sulphuric acid or, better, a strong solution of citric acid.
Potassium bromide, KBr Molec. Wt. 119	Similar to potassium iodide	See potassium iodide.
Sodium carbonate, Na₂CO₃ Molec. Wt. 106	Chlorides and sulphates	Same as for ammonia.
Sodium chloride, NaCl Molec. Wt. 58.5	Chloride of calcium Chloride of magnesium	Oxalate of ammonium (afteraddition of a little acetic acid) gives a milkiness, or precipitate, indicating calcium; filter this out and add ammonia,chloride of ammonium, and phosphate of sodium (clear solutions). A precipitate indicates magnesium. Both the abovecause dampness in wet weather.
Sodium chloride, NaCl Molec. Wt. 58.5	Sodium sulphate	As for "sulphates" in ammonia.
Potassium cyanide, KCN Molec. Wt. 65, and hydrate, KHO Molec. Wt. 56	Potassium carbonate nearly always present	Effervescence with dilute acids, giving off a gas carbonic anhydride, which renders lime-water turbid.
Kaolin	Chalk	Effervescence with dilute acids.
Water, H₂O Molec. Wt. 18	Sulphates and chlorides	Same as for ammonia.
	Calcium carbonate, temporary hardness	Deposited by boiling. Test as for calcium chloride. See sodium chloride.
	Ammonia, almost always present in distilled and rain water	Brown coloration, or precipitate with Nessler's reagent.
Gelatine	Alum	Ash, sometimes as much as ten per cent.
Gelatine	Fatty matter	Separated by precipitation with alcohol. Dissolved out by ether or benzine, and left as a residueon evaporation of the solvent.
Ammonium bromide (NH₄)Br Molec. Wt. 98	Potassium bromide or other non-volatile bodies	Leaves a residue when heated.
Ammonium bromide (NH₄)Br Molec. Wt. 98	Ammonium chloride	Same as for chlorides in ammonia.
Pyrogallic acid	Powdered glass	Left behind on solution.
Potassium iodide	Potassium bromide	The crystals of bromide are usually more transparent than those of iodide, but no reliance can be placed on this.
Silver nitrate	Potassium nitrate, sometimes present in the fused sticks—not in the crystals	Will not yield the full quantity of chloride on precipitation with HCl. Gives a purple color to flame.
Sulphuric acid	When vended as pure, it invariably contains a trace of iron. Common acid is also liable to contain arsenic, selenium, thalium, and many other substances.	No easy test can be given, as the substances are so numerous some of them volatile, and most require separation from the acid before detection.
Sulphuric acid	Organic matter, as a piece of straw in a carboy of acid	Gives a brown color to the acid.
Hydrochloric acid	Arsenic	Marsh's test.
Hydrochloric acid	Some yellow samples contain no iron, but an organic salt, and give an alkaline ash on ignition of the residue after evaporation	Reinsh's test; a small piece of copper foil becomes coated on boiling in dilute acid.
Calcium chloride	Calcium hydrate	The clear filtered solution made with distilled water is alkalineto test paper, and gives a precipitate on breathing into it through a tube.
Pure (?) chemicals generally	Broken glass, bits of straw, wood, paper, etc.	These impurities either float or sink on solution, and may easily be seen.

G.M. JONES, M.P.S.

THE CATASTROPHE AT CHANCELADE.

The Chancelade quarries near Perigneux, which caved in Oct. 22, 1885, under circumstances that are still fresh in the minds of all, have gained a celebrity that renders it unnecessary for us to revert to the details of the catastrophe. It will suffice to recall the fact that after the accident a private committee was formed for the purpose of making an attempt to save the five victims who had been surprised in the drifts, and who happened to be in the bottom levels.

FIG. 1.—PHOTOGRAPHIC EXPLORING APPARATUS.

The Lippmann establishment at once offered to make a boring by means of which it would be possible to communicate with the galleries in which the men were imprisoned, but, despite the most active efforts, success was found impossible. In order to satisfy public opinion, the committee resolved to bore a well 12 inches in diameter to a depth of 23 feet, that should permit of reaching the gallery; but this did not render the latter accessible. How was it to be seen what had occurred, how was it to be made certain that the men were dead, and that all hope of rescue must be abandoned? To Mr. Langlois, a Parisian photographer, was confided an order to construct a special apparatus which might be let down to the bottom of the well by a cord, and which, being capable of operating from a distance, should furnish the required information through sensitized plates. As may be seen, this operation presented peculiar difficulties, although Mr. Langlois was enabled to overcome these with much skill.

The photographic apparatus that the ingenious operator constructed was contained in a metallic case that could be let down into the bore hole. The upper and lower parts of the contrivance were provided with incandescent lamps, that could be lighted or extinguished from a distance, by means of conductors. The photographic apparatus, properly so called, formed of an objective and camera with its sensitized plate, was inclosed in a cylinder 3½ inches in diameter. By means of a cord drawn at the mouth of the well, the apparatus could be made to issue from its vertical sheath, and to pivot around its axis so as take views in different directions (Fig. 1).

The entire affair was suspended by twelve-foot iron rods, connected with each other end for end.

In using the apparatus, the operating was done in a shanty, which served as a dark room. The device was let down into the bore well until it touched bottom. At this moment a cord was pulled so as to raise the camera, and then a few moments were allowed to elapse in order that the apparatus might become immovable. As the objective was all the time in the dark, it had neither cap nor shutter, but was unmasked from the beginning of the operation.

In order to form an impression on the plate, it was only necessary to give light; this being easily done by passing an electric current by means of a commutator, so as to light the incandescent lamps. At the end of the exposure, the lamps were extinguished and the entire apparatus was immersed in darkness. The mean time of exposure was from four to five minutes. The apparatus was then hauled up, and the negative developed.

The experiments could be renewed as often as necessary, and the apparatus be pointed in all directions by turning it a certain number of degrees by means of a lever attached to the upper rod. In this way were obtained various views of the inaccessible gallery in different planes.

We reproduce herewith two of Mr. Langlois' most interesting photographs. One of these shows the head of the corpse of a young miner whose face stands out in relief against the side of the gallery (Fig. 2) the other shows a wheel and a lot of debris heaped up pell-mell (Fig. 3).

The series of proofs obtained from small negatives, two inches square, gave the completest sort of information in regard to the aspect of the subterranean gallery.

The exact place where the boring had been done and the entire and broken pillars were recognized, as was also the presence of two corpses, thus showing that it was indeed here that it would have been necessary to act in order to render aid to the unfortunates.

FIG. 4.—FAULT THAT CAUSED THE ACCIDENT.

In Fig. 4 is shown the appearance of the great fault that caused the accident at Chancelade. It seems to us that this method of photographing inaccessible subterranean galleries ought to receive numerous applications in the future.—La Nature.

SOMZEE'S NEW GAS-BURNERS.

With the object of effecting a very intimate mixture of gas and air, and of causing this mixture to reach the point of ignition at as high a temperature as possible, M. Leon Somzee, of Brussels, has designed several new forms of gas burner, which we now proceed to describe and illustrate, from particulars and by drawings kindly supplied by an esteemed Brussels correspondent.

The high-power burner shown in Fig. 1 effects perfect combustion of the heated mixture of air and gas, which is introduced by the draught determined by the arrangement. What chiefly distinguishes this burner from others of its class is the fact that it is perfectly suited to domestic lighting—that is to say, it may be arranged for a comparatively small consumption of gas, while giving an increase of 250 per cent. of light.

FIG. 1. and FIG. 2.
INCANDESCENT AND HIGH-POWER BURNERS.

The burner proper is a cage or basket of specially prepared magnesia, which yields a warmer tone of light than any obtained hitherto, while not requiring so high a temperature before combustion. The cap, made of a fire-resisting substance, fits on to a tubular arrangement, R, fixed in the upper portion of the body of the burner. The latter is supplied by air entering at the cone, O, which terminates the inner chamber, K, of the heater, and also by that drawn in by the rising column of gas, passing before the orifices, D, which may be regulated at will. The small burner, I, which is kept constantly alight, heats the central compartment, K, the sides of which transmit heat to the gas circulating in the annular casing, L, of the compartment. The heated gas passes, by the passage, AA¹, into the space, C, where it becomes intimately mixed with the air entering at OP, and also with the outer air arriving by the lateral apertures, D.

The vis viva of the jet is diffused through this mixture, which thus becomes very intimate, when it penetrates into the tubular arrangement, R; combustion now taking place at the top, while the refractory cap emits a bright orange light of great steadiness. As it is not the flow of gas which determines the entrance of the outer air, the former may be used at any pressure—an advantageous arrangement in all respects.

When the small burner, I, in the lower chamber is lighted, the products of combustion issue by the orifice, O, of the compartment, terminating in a needle like that of the steam injector; and the jet draws along the air entering the apertures, PP, above the cone. The gas from the pipe, arriving from the annular space, L, fills the two lateral pockets shown in dotted lines, and passes through the orifices, AA¹, which communicate with the upper chamber of the burner. The manner in which it is conveyed thence to the tubular arrangement has already been described.

Fig. 2 shows a more simple method of carrying out the same principle, and of effecting a considerable saving in gas for a given intensity of light. In this form, a wick, T, impregnated with an alkaline earthy solution, a few seconds after lighting, affords a focus of white light remarkable for its steadiness and brilliancy. A draught of air is created by a jet of gas issuing from the hollow needle, B, and passing through the vessel, D, which is provided with orifices, O, for the entrance of air. The air and gas pass from D into C, whence (after their intimate mixture is effected) they pass into the tubular arrangement, F, at the top of which combustion takes place.

To regulate the proportions in which the air and gas should mingle, in order that the combination should be as intimate as possible, the air inlet is made variable by a perforated collar, which permits of the orifices, O, being more or less covered. The other proportions of the burner—that is to say, the relative capacity of the two compartments and the length of the hollow needle—are determined by the sectional area of the supply-pipe for the gas, which is admitted under moderate pressure. Instead of a wire-gauze cap, impregnated with a solution of metals or of salts, two fine platinum wires may be used—one bent into the form of a semicircle of about an inch radius, and the other (of slightly larger diameter) rolled spirally round the former. When both ends of the two wires are connected with the upper portion of the tubular arrangement (which in this case is flattened), and the gas is ignited at the burner, the metallic arc becomes red hot, and then brightly incandescent, emitting a light, less brilliant indeed than with magnesia, but of remarkable steadiness.

In this case the production of light is chiefly due to the fact that calorific condensation, caused by the use of the helicoidal coil surrounding the curved wire, prevents loss of heat in this conductor. In these forms of high-power burner, in which the gas is used directly for the production of light, the difficulty generally encountered of heating the air (present in a larger volume than the gas) has been successfully overcome.

Fig. 3 shows the straight and outspread flame burner with a special heater. In this arrangement the gas and air are heated before combustion, in the compartment, G, directly exposed to the action of a small Bunsen burner, R, which is placed (in an opaque glass) in the middle of a lyre-shaped figure formed by the two gas-pipes, AA. The burner proper consists of two fine annular passages meeting above, and emitting a thin annular sheet of gas over the guide, T, made of a white refractory substance placed between the two annular jets. The object of this guide is to stretch the incandescent sheet of flame, composed of several jets, and interpose friction, so as to prevent a too rapid ascent of hot gases.

FIG. 3 and FIG. 4
REGENERATIVE BURNERS WITH INVERTED FLAMES.

The luminous focus is placed within a glass globe, C, mounted on the bell, B, of the heater; and the external air enters this bell, mingling with the products of combustion of the heating burner, R. The portion, D, of the annular passage, B, being made of a highly conductive metal, the gas becomes heated in passing to the burner, so that both gas and air are raised to the same temperature by the time they reach the orifices of the burner. Instead of prolonging the gas-pipe to the point of bifurcation, a chamber may be arranged immediately below the guide, for the gas and air to become intimately mixed by passing through several perforations or wire gauze, receiving the excess of heat from the white porcelain guide. The admission of gas to both the main and heating burners is regulated by a double valve in the pipe; but this arrangement may be used without any previous heating of the gas and air.

Fig. 4 shows a similar arrangement to that above described, but reversed; the gas and air being previously heated by the products of combustion. The two pipes, D, lead the gas to the burner; and the incandescent sheet of flame is drawn over a white refractory substance, having in its center an orifice through which the hot gases rise to the upper portion of the burner. The luminous sheet is spread out all the better on account of this return of the flames, which also causes the mixture of air and gas to be more complete than when they rise directly. The gas escapes horizontally from the orifices of the annular burner, B, and mingles with the double current of hot air which rushes in above the flame inside the globe, and also below through the central portion of the burner.

This lamp throws its light vertically downward; and its illuminating power may be increased by providing, above the incandescent sheet, a reflector, which diverts into a useful direction the rays thrown toward the ceiling. In this arrangement of lamp the flame is excessively condensed by its being turned back over the refractory guide; and this condensation greatly favors the production of light. On the other hand, the combustion of the gas is very perfect, because the currents of hot air are thrown directly upon the two sides of the flame; and thus the reciprocal action becomes more intense. Lastly, the division of the gas into a large number of small jets, in contact with which the hot air forms an intimate mixture, causes a greater quantity of molecules to partake in the combinations; thus affording a proportionate increase of temperature in a given space and time.

FIG. 5.
REGENERATIVE BURNER WITH FLAME DEFLECTED OUTWARD.

Owing to these various circumstances, the final effective duty of this burner is advantageous, so that it yields an illuminating power which may be put at from 200 to 250 per cent. above that of ordinary burners, and about 25 per cent. more than that of other regenerative burners. The flame is comparatively steady; the loss due to the friction over the white porcelain being almost eliminated, because the flame only presses upon the guide for a small portion of its surface, and is only spread out to the extent of its dark zone.

The contact between the incandescent sheet of flame and the guide may be made as short as desired, and the motion of the gaseous mass be directed by a simple button placed in the center of the burner; thus giving the form shown by Fig. 5, which, however, differs from the previous figure in the fact that the inverted flame is directed outward instead of inward.

In this arrangement the button, T, is fixed in the middle of the burner, which is made cylindrical and annular, or may consist of a ring of small tubes, to which the gas is led by a single pipe; leaving the whole "furnace" free for the circulation of air and the products of combustion. This is the most recent development of the principle patented by M. Somzee in 1882, viz., the formation of an illuminating sheet of flame, spread out laterally, while heating the gas and air by the products of combustion.

Figs. 6 and 7 show two forms of burner designed especially to give economical results with a small consumption of gas. The former is an ordinary Argand burner in which hot air is introduced into the upper portion of the flame, so as to increase the activity of combustion. The luminous sheet of flame is then spread out by a metal disk attached to the end of the tube, D, which introduces the air into the flame. The outer air becomes heated in its passage through the wire gauze, T, which absorbs the heat liberated in the interior of the apparatus, and also that which is radiated from the incandescent sheet and reflected by a metal shield, P, surrounding the dark part of the flame.

FIG. 6. and FIG. 7.
TYPES OF ECONOMICAL BURNERS.

It is the combustion of gas, without the production of useful luminous effect inside the shield, which supplies the reflected as well as radiated heat to the air. The temperature is still further increased by the heat transmitted to the metal portion of the burner, and absorbed by the wire gauze, between the close meshes of which the air from outside is forced to circulate. Air is admitted inside the flame by the chimney, D, placed above the focus, and in which it is raised to a high temperature by friction on the upper part of the lamp glass, at E, and afterward by its passage through the horizontal portion of the bent tube. This tube is impinged upon on the outside by the flames, and also by the products of combustion, so that it forms a veritable heater of the currents which traverse it.

The introduction of hot air into the central portion of the sheet of flame is advantageously supplemented by the spreading out of the flame by means of the metal disk, without any possibility of its being divided. In this way a more intense heat is obtained, and consequently the illuminating power is considerably increased, by the uncombined carbon being more readily set free, and being thus kept longer in the flame, F. This burner, which may be constructed for a moderate gas consumption, gives remarkable results as regards illuminating power and steadiness; the abstraction of heat in no way impairing the luminosity of the flame, which preserves all its brightness.

The Argand burner with double chimney, shown in Fig. 7, is also an economical one for a small consumption of gas. The air admitted to both the inside and the outside is raised to a high temperature by passing along the spirals of a second and transparent chimney, C¹, which surrounds the cylindrical glass, C. The gas itself is heated by passing through this hot chamber before reaching the outlet orifices; so that the mixture of air and gas takes place under the most favorable conditions for their perfect combustion.

The burner is an ordinary Argand, which may terminate below in a small chamber for the gas and air to mingle. But this is not necessary; and the usual arrangement for mixing the air and gas may be adopted. The outer air enters at the top of the central chimney, C and passes into the annular space between the two glasses; then descends by the two spiral passages, which surround the cylindrical glass and terminate in a portion hermetically sealed by a brass plate attached to the supply-pipe. All the parts of the burner are thus surrounded by a highly-heated atmosphere, especially at the bottom of the double chimney; and it will be readily understood that, if the branches which lead the gas to the burner are constructed of a highly conductive metal, the gas will become heated in its turn by passing through passages raised to a high temperature.

The elements are therefore dissociated or separated before their final combination; thereby raising the calorific and luminous effect to the highest possible degree. Such a burner can, of course, be made as small as may be required; thus lending itself admirably to the subdivision of illumination. The only precaution required is to properly proportion the sectional area of the hot-air passages to the radiant surface of the flame, so that the heat does not become too intense at the lower portion of the burner.

Fig. 8 shows a double flame burner on the principle of Mr. Heron's, but with admission of hot air into the angle formed by the flames. As exemplified by Mr. Heron, if two equal batswing burners separately give a certain amount of light, on the two flames being brought into contact, so as to form a single flame, the luminosity is considerably increased, owing to the condensation of heat which results from their meeting. The two incandescent sheets are, as it were, forced into one another, so as to be combined.

FIG. 8.
DOUBLE FLAT-FLAME BURNER

The high-power burners of Douglass, Coze, Mallet, and others were designed on this principle; but its application to uninclosed burners was not very satisfactory, because the great cooling down of the inner surface of the flames by the strong draught of cold air impaired their illuminating power. To counteract this difficulty, M. Somzee adopts a heating burner, A, which he places between the two batswing burners, B, so that the products of combustion rise in the angle made by the two lighting flames, as shown; thus greatly increasing their luminosity while maintaining a low consumption of gas.

M. Somzee also raises the illuminating power of an ordinary flat-flame burner by causing an obscure effluvium to traverse the dark portion of the flame. The effect of this is to increase the activity of decomposition in this portion, so that the particles of carbon are the more readily set free, and remain longer in suspension in the luminous zone. The obscure effluvium may be determined between two points by the electric current, or be caused by the heating of an imperfect conductor by the current; or, again, it may result from a metal conductor heated by the reactions produced in the middle of the flame, by separating the cone of matter in ignition. The effect may be compared with that obtained by the concentration of two sheets of flame; but in this case the sheets are formed by the constituent parts of one and the same flame, whence results a more complete utilization of the elements composing it. This system is, in fact, a simplification of the arrangement adopted in the double-flame burner seen in Fig. 8.

Fig. 9 shows a reflecting and regenerative burner with double glass. The crown, made of metal polished on both sides, has a circular groove, G, for receiving the end of the central chimney, C, and presenting an annular aperture by which the products of combustion enter. The second glass, C¹, is fastened to the collar of the burner carrier, and does not come into contact with the metal crown; so as to allow the air to enter from outside for supplying the burner. The gas enters by the pipe, T, provided with a cock. This pipe is continued to the top of the apparatus, and there spreads out into the form of a dome; thus dividing into two compartments the trunconic chamber, S¹ S², whence the hot gas returns to the body of the burner, B.

FIG 9.
REFLECTING AND REGENERATING BURNER.

On the burner being lighted from below, the products of combustion rise in the inner chimney, and enter the heater, which they traverse through its entire extent, while impinging against the outside of the gas reservoir, to which they give up a large portion of their heat. They then pass by the passage, D, into the atmosphere or into a chimney. The air necessary for combustion enters at the top of the outer globe, and becomes highly heated in its passage through the space comprised between the two glasses of the burner. In this way it reaches the burner, and forms an intimate mixture with the small jets of gas which compose the flame. The gas, on leaving the supply-pipe, T, fills one of the compartments, S¹ S², of the heater, and then returns by the second compartment, and again descends by the casing of the supply-pipe, having its temperature still further raised by contact with the internal radiation of the flame.

Under these conditions, all the parts of the burner are supplied by heated air, and the combustion becomes very active; thus increasing the intensity of the flame, and consequently that of the light afforded, while at the same time effecting a saving of 50 per cent. of gas. This burner may be made of any size, and for consumptions not exceeding that of an ordinary Argand. In fact, the gas is consumed at a low pressure, escaping with no greater force than that due to the heat of the products of combustion. It is sufficiently expanded on coming into contact with the current of hot air, the activity of which is regulated by the height of the apparatus, that is to say, by that of its two chimneys. The mixture is made in such proportion as to obtain from the gas and air as great a degree of luminosity as possible. The high temperature of the gas, and the independent means of heating the air and gas, constitute the essential principles of this burner.—Journal of Gas Lighting.

THE CLAMOND GAS BURNER.

In this burner, which is a French invention, the light is produced by burning ordinary coal gas within a basket of magnesia, which is thereby brought to a high state of incandescence, and from which a white, steady light is radiated. It may be said to consist of three different parts. The first and inner part is a central column, B, of fireproof material. The second part consists of two concentric cylinders placed round the inner column and communicating one with the other through the cross cuts, J. The third part is a china cup inclosing the other parts, and perforated with a number of holes. The gas burns in two different places. From A it passes directly through B, at the top of which it branches off through tubes to an annular chamber, D, from which it escapes through the openings, a, a, a, where combustion takes place. The other combustion occurs within the circular space, G, I, between the column and the inner of the two surrounding cylinders, through two channels, E E, in the lower part of the central column. The gas passes into a circular chamber, F F, and escapes through small holes in the upper partition of this chamber, where it burns. The product of this combustion passes put into K, through the cross cuts, J. The air entering through the holes, H L, of the outer china cup passes along the inner of the two concentric cylinders, which is heated to redness, and rises highly heated toward the upper annular burner, where the gas burns at a, a, a, in small separate flames, each entirely surrounded by the hot air. This insures perfect combustion of the gas within the basket of magnesia placed above, and which is thus brought to a state of incandescence. It will be seen from this description how simple and practical the arrangement is. It is claimed for the light produced that it will stand comparison with the electric light. Like that, it shows colors perfectly true, and will enable an observer to distinguish between the most delicate shades, allowing of the finest work being executed as by daylight. It is, moreover, stated to be perfectly steady. As the Clamond burner can be fixed to any gas bracket or lamp now in use, its adoption causes no other expense than the cost of the burner itself. There is no expensive installation, and when used in combination with the electric light, it is claimed that a uniform lighting will be obtainable instead of the unpleasant contrast between gas and electricity. Another important advantage obtained by the Clamond burner is the saving effected in the consumption of gas as compared with the same power of light obtained from ordinary burners.

A NEW THERMO-REGULATOR.

In the thermo-regulators which have been constructed heretofore, the heat has been regulated by the variation in the inflow of gas to the heating flame. The apparatus described below, and shown in the accompanying cut, taken from the Zeitschrift fur Instrumentenkunde, operates on an entirely different principle. The distillation and condensation process of a fluid heated to the boiling point in the vessel, A, is as follows:

The steam passes first through the pipes, a and c, into the serpentine tube, where it is condensed, and then flows through the tubes, d and b, back into the vessel, A, if the cock, r, is closed, but if the said cock is open, it flows into the receptacle, K. When the liquid begins to boil the steam passes freely through the tubes, d and b, part passing through the tube, f, out into the air, and the other part passing through the open cock, r, to the receptacle, K; but the condensed liquid soon closes these passages to the steam. At h is an opening for a thermometer, t, and through this opening the liquid can be poured into the vessel, A. If the cock, r, is kept closed, the volume of liquid in the vessel, A, cannot be diminished, and the bath, B, must take the constant and uniform temperature of the steam in the vessel, A, as the vessel, B, is heated evenly on all sides.

This apparatus can also be used as an air bath, in which case the vessel, B, is left empty and closed by a suitable stopper.

PIPETTE FOR TAKING THE DENSITY OF LIQUIDS.

The accompanying engraving represents a simple apparatus, which any person accustomed to working glass can make for himself, and which permits of quickly, and with close approximation, estimating the density of a liquid. In addition, it has the advantage of requiring but a very small quantity of the liquid.

It consists simply of a straight pipette, A B, to which is affixed laterally, at the upper part, a small U-shaped water gauge.

The two branches of the gauge, as well as the pipette itself, are graduated into equal divisions. If need be, the graduating may be done by simply pasting on the glass strips of paper, upon which a graduated scale has been drawn. The zero of the pipette's graduation is exactly at the lower extremity, B. The graduation of the two gauge tubes extends in both directions from a zero situated near the center. The zeros of the two branches must correspond as exactly as possible, so that they shall be in the same horizontal plane when the apparatus is fixed upon a support. To render the apparatus complete, it only remains to adapt, at A, a rubber tube provided with a wire clamp, and terminating in a short glass tube for sucking through with the mouth.

PIPETTE FOR TAKING THE DENSITY OF LIQUIDS.

For taking the density of a liquid, we plunge the end, B, into it, and then suck, and afterward close the rubber tube with the clamp. It is essential that this latter shall hold well, so that the levels may remain constant.

We now do the reading. Suppose, for example, we read 250.3 mm. on the pipette, and 147.7 mm. and 152 mm. on the branches of the gauge. Having these data, we loosen the clamp, and allow the liquid to flow. On account of capillarity, there remains a drop in B; and of this we read the height, say 6 mm. A height 250.5 mm - 6 = 244.5 mm. of liquid raised is, then, balanced by a column of water of 147.5 + 152 = 299 mm.

Now the heights of these two liquids is in the inverse ratio of their densities:

d
1

299.5
244.5

, whence d = 1.22.

We obtain d by a simple division.

When the instrument has been carefully graduated, and has been constructed by an expert, the accuracy of the first two decimals may be relied upon. With a little practice in estimating the last drop, we may, in trying to estimate the density of water, even reach a closer approximation. In order to measure the height of the drop accurately, one should read the maximum height to which the liquid rises between the fall of two drops at the moment when the last ones are falling, since at that moment, and only at that, can it be ascertained that the lower level of the bubble is plane. The error in such reading does not reach half a millimeter, and, as a suitable height of the apparatus permits of having columns that vary between 13 and 30 centimeters, an error of this kind is but 1-300. This is the limit of precision of the method.

The clamp might be advantageously replaced by a glass cock, or, better still, A might terminate in a rubber bulb; and a lateral tubulure might be fixed to the pipette, and be closed with a rubber stopper.

This little apparatus is more easily maneuvered than any of those that have hitherto been devised upon the same principle. It is capable also of replacing areometers in ordinary determinations, since it permits of correcting the error in capillarity that is neglected in instruments; and, moreover, one can, when he desires to, easily verify for himself the accuracy of the graduation.—La Nature.

USEFUL BAGS, AND HOW TO MAKE THEM.

By JOHN T. HUMPHREY.

Since the papers on "Boot and Shoemaking," in vol. i. of Amateur Work, illustrated, I think nothing relating to the leather trades has appeared in it; and as there must be many among the readers of this magazine who have a desire to dive deeper into the art of manipulating leather into the various articles of utility made from that material, I will endeavor in the series of articles of which this is the commencement to furnish them with the necessary instructions which will enable them to do for themselves many things which now are left undone, or else have to be conveyed miles to some town where the particular business, or something akin to it, is carried on. To the colonist and those who live in out-of-the-way districts, it must be a matter of great regret to observe articles of use, where the material is in good condition, rapidly becoming useless owing to the inability of the possessor to do the necessary repairs. Again, it may be that the article is completely worn out, and the old proverb that "a stitch in time saves nine," will not be advantageously applied if carried out. In that case a knowledge of making new what we require, whether in order to replace something already worn out or as an addition to our store, must prove beneficial to the thrifty amateur. My object in writing these articles is not to deprive the mechanic of any portion of his legitimate occupation, but to assist those who live at a distance too great to be able to employ him, and who necessarily prefer any makeshift to the inconvenience of sending miles, and being without for days, an article which might possibly be set right in an hour or two.