Chapter 7

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.

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.

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.

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.

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.

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_ 299.5 --- = -----, whence _d_ = 1.22. 1 244.5

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.

HOW TO MAKE BAGS.

The old-fashioned carpet bag (Fig. 1) is still unsurpassed by any, where rough wear is the principal thing to be studied. Such a bag, if constructed of good Brussels carpeting and unquestionable workmanship, will last a lifetime, provided always that a substantial frame is used.

Next in order comes the brief bag (Fig. 2), more extensively used than any other. For business purposes it is in great favor with bag users, being made in a variety of shapes, but all belonging to the same class. Here we have the shallow brief, deep brief, eclipse wide mouth, imperial wide mouth, excelsior, courier, and many others; but to know how to make one will be sufficient for all, the only difference being in the cut or style in which they are constructed.

The cricket bat bag (represented in Fig. 3) is made on the same principle throughout as the carpet bag.

Frames and all necessary fittings required in making bags may be purchased of dealers.

Care must be observed in choosing all the pieces necessary for a bag from the same pattern carpet, otherwise it will present an unsightly appearance when completed. There may be some who would prefer American cloth; this is thoroughly waterproof, and has a good appearance for some time, but, like all articles of imitation, it has only _cheapness_ to recommend it. If cloth is to be used (I mean American cloth), let it be the best that can be bought, that which is called "double-twill duck," if possible. As the making is the same whether cloth or carpet be used, it will be understood that the instructions for making apply to both.