Chapter VIII: MISCELLANEOUS.--Our Hebrew Population (2)

The accompanying cuts represent two new machines for binding together books and pamphlets. They are the invention of Messrs. Brehmer & Co., and are now much used in England and Germany. The material used for binding is galvanized iron wire.

_Machine Operated by Hand_ (Fig. 1).--This machine serves for fastening together the pages of pamphlets through the middle of the fold, or for binding together several sheets to form books up to a thickness of about half an inch.

It consists of a small cast-iron frame, with which is articulated a lever, _i_, maneuvered by a handle, _h_. This lever is provided at its extremity with a curved slat, in which engages a stud, fixed to the lower part of a movable arm, _c_, whose extremity, _d_, rises and descends when the lever handle, _h_, is acted upon. This maneuver can be likewise performed by the foot, if the handle, _h_, be connected with a pedal, X, placed at the foot of the table that supports the machine, as shown in Fig. 2. The lever, _i_, is always drawn back to its first position, when left to itself, by means of the spring, _z_.

The staples for binding have nearly the form of the letter U, and are placed, to the number of 250 or 300, on small blocks of wood, _m_. To prepare the machine for work, the catch, _a_, is shoved back, and the whole upper part of the piece, _b_, is removed. The rod, _e_, with its spring, is then drawn back until a small hole in _e_ is perceived, and into this there is introduced the hook, _f_, which then holds the spring. The block of wood, _m_, filled with staples, is then rested against a rectangular horizontal rod, and into this latter the staples are slipped by hand. The upper part of the piece, _b_, is next put in place and fastened with the catch, _a_. Finally, the spring is freed from the hook, _f_. When it is desired to bind the pages of a pamphlet, the latter is placed open on the support, _g_, which, as will be noticed, is angular above, so that the staple may enter exactly on the line of the fold. Then the handle, _h_, is shoved down so as to act on the arm, _c_, and cause the descent of the extremity, _d_, as well as the vertical piece, _b_, with which it engages. This latter, in its downward travel, takes up one of the staples, which are continually thrust forward by the rod and spring, and causes it to penetrate the paper. At this moment, the handle, _h_, makes the lever, _n_, oscillate, and this raises, through its other extremity, a vertical slide whose head bends the two points of the staple toward each other. The handle, _h_, is afterward lifted, the position of the pamphlet is changed, and the same operation is repeated. When it is desired to form a book from a number of sheets, the table, _l_, is mounted on the support, _g_, its two movable registers are regulated, and the sheets are spread out flat on it. The machine, in operating, drives the staples in along the edge of the sheets, and the points are bent over, as above indicated.

The axis on which the lever, _i_, is articulated is eccentric, and is provided on the side opposite the lever with a needle, _k_, revolving on a dial. The object of this arrangement is to regulate the machine according to the thickness of the book.

_Machine to be Operated by a Motor_ (Fig. 3).--This machine, although working on the same principle, is of an entirely different construction. It is designed for binding books of all dimensions. It consists of a frame, _a_, in two pieces, connected by cross-pieces, and carries a table, _u_, designed to receive the sheets before being bound together. Motion is transmitted by means of a cone, _c_, mounted loose on the shaft, _b_. To start the machine, the foot is pressed on the pedal, _m_, which, through the intermedium of links and arms, brings together the friction plates, _d_, one of which is connected with the shaft, _b_, and the other with the cone, _c_. When it is desired to stop the machine, the pedal is left free to itself, while the counterpoise, _s_, ungears the friction plates. The machine fastens the paper with galvanized iron wire wound round bobbins placed at the side of the apparatus. This wire it cuts, and forms into staples.

The book to be bound is placed on the support, _h_, and the arms, _k_, that carry the fasteners cause it to move backward and forward. It also undergoes a second motion--that is, it moves downward according to the number and thickness of its pages. This motion, which takes place every time the operator adds a new sheet, is regulated by a cog-wheel register, _l_, which is divided, and provided with a needle.

The iron wires pass from the bobbins on a support to the left of the machine by means of feed rollers, which thrust them through the eight clips. In the interior of these latter there is a double knife, which, actuated by one of the cams of the wheel, _e_, cuts the wire and bends it thus [Inline Illustration]. The extremities of the staples are thrust through the back of the half opened leaves, and then bent toward each other thus [Inline Illustration], by the front fastener. This motion is effected by means of two levers, _p_ (moved by the cams, _e_), whose extremities at every revolution of the machine seize by the two ends a link that maneuvers the fasteners. The binding of one sheet finished, the lower arms of the machine again take their position, the wires move forward the length necessary to form new staples, a new sheet is laid, and the same operation is proceeded with. The number of staples and their distance are changed, according to the size of the book, by introducing into the machine as much wire as will be necessary for the staples. To prevent their number from increasing the thickness of the back of the book (as would happen were they superposed), the support, _h_, moves laterally at every blow, so as to cause the third staple to be driven over the first, the second over the fourth, etc.

* * * * *

FLUMES AND THEIR CONSTRUCTION.

In crossing ravines in this State, flumes or wrought iron pipes are used. Many miners object to flumes on account of their continual cost and danger of destruction by fire. Where used and practicable, they are set on heavier grades than ditches, 30 to 35 ft. per mile, and, consequently, are proportionately of smaller area than the ditches. In their construction a straight line is the most desirable. Curves, where required, should be carefully set, so that the flume may discharge its maximum quantity. Many ditches in California have miles of fluming. The annexed sketch, drawn by A. J. Bowie, Jr., will show the ordinary style of construction.

The planking ordinarily used is of heart sugar pine, one and a half to two inches thick, and 12 to 18 inches wide. Where the boards join, pine battens three inches wide by one and a half thick cover the seam. Sills, posts, and caps support and strengthen the flume every four feet. The posts are mortised into the caps and sills. The sills extend about 20 inches beyond the posts, and to them side braces are nailed to strengthen the structure. This extension of the sill timbers affords a place for the accumulation of snow and ice, and in the mountains such accumulations frequently break them off, and occasionally destroy a flume.

To avoid damage from slides, snow, and wind storms, the flumes are set in as close as possible to the bank, and rest, wholly or partially, on a solid bed, as the general topography and costs will admit. Stringers running the entire length of the flume are placed beneath the sills just outside of the posts. They are not absolutely necessary, but in point of economy are most valuable, as they preserve the timbers. As occasion may demand, the flume is trestled, the main supports being placed every eight feet. The scantling and struts used are in accordance with the requirements of the work.--_Min. and Sci. Press_.

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CHUWAB'S ROLLING MILL FOR DRESSING AND ROUNDING BAR IRON.

This new forge apparatus has been devised for the purpose of finishing up round irons of all diameters while hot, as they come out of the ordinary rolling mill, by rendering them perfectly circular, cylindrical, straight, smooth, and level at the extremities, as if they had passed through a slide lathe. Such a high degree of external finish is a very valuable feature in those round irons that are employed in so great quantity for shafting, cylindrical axles, etc., as well as in the manufacture of bolts and locks. Figs. 1, 2, 3, and 4 of the opposite engraving will allow it to be seen that this apparatus which is usually installed at the side of the finishing cylinder is, in part, beneath the general level of the forge floor. It may be placed parallel with or perpendicular to the apparatus that it does duty for, this depending upon the site at disposal or the mode of transmission.

The apparatus consists essentially of two tempered iron cylinders, A, 0.5 of a meter in diameter by 1.5 meters in length, revolving in the _same direction_ (contrary to what takes place in ordinary rolling mills) between two frames, B, that are open on one side to allow of the entrance of the finishing bar. This latter is held between the cylinders, A, which roll it so much the faster in proportion as its diameter is smaller, and by a scraper guide, C, of the same length as the cylinder table, and which may be regulated at will by bolts, c, fixed to the frame, B. The bottom cylinder remains always in the same position, while the axle, D, which carries the intermediate wheels, E, moves about to gear in all the relative positions of the cylinders. The displacement of the upper cylinder is effected through the clamping screws, b, which are actuated by toothed disks that gear with two endless screws keyed at the extremities of one shaft in common, d, which is set in motion by hand through the winches, m m. The scraper guards, e e, take up and throw aside all scales that might become attached to the cylinders, which are constantly moistened by small streams of water coming from an ordinary conduit.

Fig. 1--Elevation and Longitudinal Section.

Fig. 2--Side View.

Fig. 3--Transvers Section.

Fig. 4--Plan View.

Figs. 5 & 6--Saws for Dressing the Extremities of the Bars.

Fig. 7--Diagram Showing the Motion of the Wheels and Guide.

Figs. 8 & 9--Apparatus for Shifting tha Bars.]

As the driving belts are mounted on pulleys, G, of a diameter proportioned to the velocity of the shafting, the iron pinions, h, in order to produce 60 revolutions per minute in the first shaft, H, gear on each side with the intermediate wheels, E, and these actuate the two bronze pinions, a a, that are mounted on the extremities of the cylinders, A A. The axle, D, of the intermediate wheels does not revolve with them, but is capable of rising and descending in the elongated aperture that traverses the frames, B. The displacement of this axle is secured through the arms, L L, whose extremities articulate on the one hand with the cylinders, A A, and on the other with D. The result of this is that every displacement upward of the top cylinder corresponds to a different position of the intermediate shaft, and one that is always equidistant from the centers of the cylinders, A A, thus securing a constant gearing of the wheels in all the positions of the cylinders, A A.

The diagram in Fig. 7 shows the relative displacements of all these parts, as well as those of the scraper guide, C. The diameter to be obtained is determined beforehand by the two contact screws, P.

The whole thus regulated, the bar of iron, still very hot, coming from the ordinary rollers, is straightened up, if need be, by a few blows of a hammer, so that it may roll forward over the pavement, N, between the rounding cylinders, A A; these being held apart sufficiently to allow of its easy introduction. Next, a few revolutions of the winches that control the screws suffice to lower the upper cylinder to the exact position limited by the contact screws, P, and the bar is rolled between the two cylinder tables with a constant velocity in the generatrices. As a consequence, the number of revolutions made is so much the greater in proportion as the diameter of the shaft is smaller with respect to that of the cylinders.

It should be remarked that the bar, during its rotation under pressure, is held by the guide, C, so that its diagrammatic axis (Fig. 7) exceeds the line, A A, joining the centers of the cylinders just enough to prevent its escape to the opposite, and so that the pressure upon the said guide (which performs the role of scraper) is merely sufficient to detach the scales which form during the operation.

Under such conditions, and at a velocity of 30 revolutions per minute in the two cylinders, it will take but a fraction of a minute to finish a bar the length of the table, that is to say, 1.5 meters. Then, by loosening the upper cylinder, the bar may be easily shoved along in one direction or the other, so as to continue the finishing operation on successive lengths. This moving of the bar forward is further facilitated by the aid of a clamp with rollers and a movable socket, V (Figs. 8 and 9). For large diameters (150 millimeters and beyond) traction is employed by the aid of two small windlasses placed opposite each other, and at a distance apart twice the greatest length of the bars to be finished. The chains of these windlasses are attached to the extremities by clamps that lock by the pulling exerted.

The details of the arrangement of the saws (Figs. 5 and 6) show that to make a section of the ends or of any other part of the bar, it is only necessary to lower the lever of one them. By reason of the contrary rotation of the bar, the effective stress on the lever will be very moderate, while the cut produced will be a clean and quickly performed one. It should be remarked that, as a consequence of the cone on the projecting extremity of the cylinder journals (Fig. 5), and on the rollers that control the saws, it is only necessary to move the lever to the right or left in order to stop the motion of each of the saws. These latter, to prevent all possibility of accident, are inclosed within semicircular guards. Finally, the controlling rollers are made of a material which is quite elastic (compressed cardboard, for example), so that they may roll smoothly and adhere well.

From what precedes, it will be seen that round iron bars of any diameter will come from this apparatus completely finished. It will be seen also that with cylinders of suitable profile, there might likewise be finished axles, or pieces that are more or less conical as well as those provided with shoulders.

The apparatus may, if preferred, be driven by small special motors affixed to the frame. Such an arrangement, which is more costly than the preceding, is, nevertheless, indicated in cases where shafting would be in the way.

The weight of the materials entering into the construction of this machine, proposed by Mr. Chuwab, includes about 15 tons of metal, of which 5,000 kilogrammes are for the two tempered cylinders; 250 kilogrammes of iron screws, and 350 of bolts; and 500 kilogrammes of bronze, 90 of which are for nuts.--_Revue Industrielle_.

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THE BURNING OF TOWN REFUSE AT LEEDS.

[Footnote: From selected papers of the Institution of Civil Engineers, London, by Charles Slagg, Assoc. Memb. Inst. C.E.]

In large towns it is necessary to adopt some regular system of removal and disposal of the cinders and ashes of house fires, and of the animal and vegetable refuse of the houses, and, in short, of everything thrown away which cannot be admitted into the sewers. In towns where the excreta are separated by means of water closets, the disposal of the other refuse presents less difficulty, but still a considerable one, because the animal and vegetable refuse is not kept separate from the cinders and ashes, all being thrown together into the ash pit or dust bin. The contents, therefore, cannot be deposited upon ground which may afterward be built upon, although that custom obtained generally in former times. Hence the refuse has been removed to a depot where that wretched industry is created of picking out the other parts from the cinders and ashes.

Elevation.

Section through feeding-holes of cells.

Section through air-passages of cells.]

But in towns unprovided with water closets, or so far as they are not adopted in any town, where the privies are connected with the ash pits, and where, consequently, the excreta of the population are added to the other contents of ash pits, the difficulties of removal and disposal of the refuse are much increased.

Where the privy-ashpit system is in use--as it still is to a large extent--as much of the contents of the ash pits as can be sold at any price, however small, are collected separately from the drier portions, and sent out of town as manure; but what remains is still too offensive to be deposited on ground near the town; and when it is attempted to collect the excreta separately by the pail system, the process is no less unsatisfactory. These difficulties led to the adoption, under the advice of the late Mr. A.W. Morant, M. Inst. C.E., the Borough Engineer at Leeds, of Fryer's method of destruction by burning--that is, of the dry ashes and cinders and the animal and vegetable refuse. The author was Mr. Morant's assistant. The first kiln was constructed at Burmantofts, 1½ miles from the center of the town in a northeasterly direction, and has been in use since the beginning of the year 1878. In 1879 another kiln was constructed at Armley Road, a mile from the center of the town in a west-southwesterly direction, which has been in use since the beginning of 1880.

Each destructor kiln has six cells, three in each face of a block of brick work 22 feet long, 24 feet through from face to face, and 12 feet high. Each cell is 8 feet long and 5 feet wide, arched over, the height being 3 feet 4 inches, and both the bottom and arch of the cell slope down to the furnace doors with an inclination of 1 in 3. The lower end of each cell has about 26 square feet of wrought-iron firebars, the hearth being 4½ feet above the ground.

Section through furnaces.

Longitudinal section.

Cross section.]

There are two floors, one on the ground level, a few feet only above the outlet for drainage, the other floor, or raised platform, being 15 feet above it. The refuse is taken in carts up an incline of 1 in 14 on cast-iron tram plates to the upper floor, and deposited upon and alongside of the destructor, and is shoveled into a row of hoppers at the head of the cells. These hoppers are in the middle of the width of the destructor, and each communicates with a cell on each side of it. The refuse is always damp, and often wet, and after being put into the cells is gradually dried by the heat reflected upon it from the firebrick arch of the cell, before it descends to the furnace. This distinguishes the system from the common furnace, and enables the wet material to be burned without other fuel. No fresh fuel is used after the fires are once lighted. The vapor passes off with the gases of combustion into a horizontal flue between the two rows of cells, through an opening at the head of each cell, alongside that through which the refuse is fed into it, the two openings being separated by a firebrick wall. The refuse is prevented from falling into the flue by a bridge wall across the outlet opening, over which the gases pass into the flue.

Between the destructor and the chimney a multitubular boiler is placed, which makes steam enough for grinding into sand the clinkers which are the solid residue of the burnt refuse. At Burmantofts an old chimney was made use of, which is but 84 feet high; but at Armley Road a new chimney was built, 6 feet square inside and 120 feet high. It is necessary to make the horizontal flue large; that at Armley Road is 9 feet high and 4 feet wide. A large quantity of dust escapes from the cells--about 7 cwt. a month--and unless the velocity of the air in the flue between the destructor and the chimney were checked, the dust would be carried up the chimney and might cause complaints; as, indeed, it has done with the 120-foot chimney, but whether with any substantial grounds is uncertain. The dust is removed from the horizontal flue or dust chamber once a month. Experience seems to indicate that there should be some sort of guard or grating to prevent the entry into the chimney of charred paper and similar light substances which do not fall to dust, and which are sometimes carried up with the draught.

A six-celled destructor kiln burns about 42 tons of refuse in twenty-four hours, leaving about one-fourth of its bulk of clinkers and ashes. The clinkers are withdrawn from the furnaces five times each day and night, or about every two-and-a-half hours, into iron barrows, and wheeled outside the shed which covers the destructor, and when cold are wheeled back to the mortar mills, of which there are two at each depot, each having a revolving pan 8 feet in diameter, with 27-cwt. rollers, the pan making twenty two revolutions a minute. Forty shovelfuls of clinkers and twelve of slaked lime make 7 cwt. of mortar in thirty-five minutes in each pan, which is sold at 5s. 6d. per ton. The engine driving the two mortar mills has a 14 inch cylinder, 30 inches length of stroke, and makes sixty revolutions per minute with 45 pounds steam pressure per square inch in the boiler, when both mortar mills are running. The boiler is 11 feet long, 8 feet in diameter, and has 132 tubes 4 inches in external diameter, which, together with the external flues, are cleaned out once a month.

At first sight it would probably appear that no good mortar could be made from such refuse as has been described, but having passed through the furnace, the clinkers are, of course, perfectly clean, and with good lime make a really strong and excellent mortar. They are also largely used for the foundation of roadways.

The number of men employed is as follows: Two furnace men in the daytime and two at night. They work from midnight on Sundays to 2 P.M. on Saturdays, the fires being fully charged and left to burn through the Sundays. One foreman, who attends also to the running of the engine, and one mortar man. A watchman attends while the workmen are off.

In addition to a destructor, there is at the Burmautofts depot a "carbonizer" kiln, in which the sweepings of the vegetable markets are burned into charcoal. The carbonizer consists of eight vertical cells, in two sets or stacks of four, separated by a space containing two double furnaces, back to back, there being a double furnace also at each end of the eight cells. Each of the stacks of four cells is 15 feet 6 inches high; the ends and middle parts, forming the tops of the furnaces, being 6 feet high. The block of brick work containing the eight cells and furnaces is 26 feet 6 inches long and 12 feet 4 inches wide at the floor level. Each cell is 3 feet 6 inches by 2 feet, and about 10 feet deep, with a chamber below about 3 feet deep, into which the charred material falls and is completely burned. The top of the cells is level with the upper platform, and they are fed through a loose cover, which is immediately replaced. Inside the cells cast-iron sloping shelves are hung upon the walls so that their upper edges touch the walls, but the lower edges are some inches off, so that the hot air of the furnaces passes upward behind the shelves round the four sides of the cell in a spiral manner, and out near the top into a vertical flue, which conducts it down to the horizontal flue at the bottom, which leads to the chimney. The charcoal is withdrawn from the bottom of the heating chamber through a sliding plate 2 feet above the floor, and is wheeled red hot to the charcoal cooler, which is a revolving cylinder, nearly horizontal, kept cool by water falling upon it, and delivers the charcoal in two degrees of fineness at the end. It is worked by a small attached engine, supplied with steam from the boiler before mentioned. Each cell of the carbonizer can reduce to charcoal 50 cwt. of vegetable refuse in twenty four hours, but at Leeds not quite so much is put through. The quantity of market refuse passed through six cells of the carbonizer varies from 3 to 10 tons a day, and averages about 4½ tons, from which 15 cwt. of charcoal is obtained. The fuel for burning the charcoal is derived from the ash pit refuse, some selected loads being for that purpose passed over a sloping screen fixed between the upper platform and the furnace floor, the fine ashes which pass through the screen being taken away to the manure heaps, and the combustible parts to the furnaces of the carbonizer. In this way a good deal of the ash pit refuse is got rid of; it is often one-twelfth part of the whole quantity.

The carbonizer and the destructor are set 33 feet apart, to allow room for drawing the furnaces and for the mortar mills, but the space is hardly sufficient. One man is employed in attending to the carbonizer.

Besides the openings at the top of the destructor through which the ash pit refuse is fed into the cells, there is a larger opening in each cell, kept covered usually, through which bed mattresses ordered by the medical sanitary office to be destroyed can be put into the cells. These openings are midway between the central openings and the furnace doors, and whatever is put into the cells through these comes into immediate contact with the fire. Advantage is taken of these openings for the destruction of dead animals and diseased meat, and as much as 20 tons in a year have been passed through the destructor.

The whole works are roofed over. The lower floor is open on two sides, but the upper one is closed in, with weather boarding at Burmantofts and with corrugated iron at Armley Road. At the former place the works were in some measure experimental, and the platform was constructed of timber, but at Armley Road it is of plate-iron girders, with brick arching, weight being considered advantageous in reducing the vibration of carting heavy loads over it.

The cost of each depot has been £4,500, exclusive of land, of which about an acre is required for the destructor, carbonizer, inclined road, weigh office, and space. A supply of water is necessary, a good deal being required for cooling the clinkers. The population of the two districts belonging to these works is about 160,000.

The author has no longer any connection with the works described, and for the recent experience of their working he is indebted to Mr. John Newhouse, the superintendent of the sanitary department of the corporation.

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GREEN WOOD.

The specific volume of the different constituents of green woods has been estimated by M. Hartig to be as follows, per 1,000 parts: Hard green wood, fiber stuff, 441; water, 247; air, 312. Soft green wood, fiber stuff, 279; water, 317, air, 404. Evergreen wood, fiber stuff, 270; water, 335; air, 395. A certain amount of water--7 or 8 per cent in all--is included with the fiber stuff, showing that about one-third only of the mass of the wood is solid stuff; the remainder is either water or air space.

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THE ARMITAGE HOUSE.

This house is now in course of erection under the superintendence of Messrs. Salomons and Ely, in the Claremont road, Pendleton, near Manchester. The walls are faced in the lower part with red bricks, and red stone, from the neighborhood of Liverpool, is used for the window-dressings, etc. The upper part of walls will be faced with red tiles and half-timber work, and the roof will be covered with Staffordshire tiles. Lead lights will be largely used in the windows. Internally, the finish will be almost entirely in real woods, including walnut for the dining-room and vestibule, pitch-pine for the large hall, staircase, and billiard-room, ash for the morning-room, and oak for Mr. Armitage's own room. In all these the ceilings and dados are to be in wood. The contract for the whole of the above work, amounting to £6,507, is let to Mr. James Herd, of Manchester.--_Building News_.

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THE COLLOTYPE PROCESS IN PRACTICE.

That theory and practice are two very different things holds good in photography especially, and perhaps in no other branch of our art have so many theoretical formulæ been promulgated as in the collotype or Lichtdruck process. As our readers are aware, we have had an opportunity of seeing collotype printing in operation in several European establishments of note, and have, from time to time, published in these columns our experiences. But requests still come to us so frequently for information on the process that we have deemed it well to make a practical summary for the benefit of those who are working--or desire to work--the method.

The formulæ and manipulations here set down are those of Löwy, Albert, Allgeyer, and Obernetter, four of the best authorities on the subject, and we can assure our readers there is nothing described but what is actually practiced.

_Glass Plate for the Printing Block_.--Herr Albert, of Munich, uses patent plate of nearly half an inch in thickness, as most of his work is printed upon the Schnell press (machine press). Herr Obernetter, of Vienna, since he only employs the slower and more careful hand press, prefers plate glass of ordinary thickness as being handier in manipulation and better adapted to the common printing-frame.

Herr Löwy, of Vienna, again, uses plate glass a quarter of an inch thick, as his productions range from the finest to the roughest.

_Preliminary Coating of the Glass Plate_.--Herr Albert's original plan was to apply a preliminary coating of bichromated gelatine to the thick glass plate, the film being exposed to light through the back of the glass, and thus rendered insoluble and tightly cemented to the surface; this film serving as a basis for the second sensitive coating, that was afterward impressed by the negative. This double treatment is now definitely abandoned in most Lichtdruck establishments, and, instead, a preliminary coating of soluble silicate and albumen dissolved in water is used.

Herr Löwy's method and formula are as follows: The glass plate is cleaned, and coated with--

Soluble glass. 3 parts.
White of egg. 7 "
Water. 9 to 10 "

The soluble glass must be free from caustic potash. The mixture, which must be used fresh, is carefully filtered, and spread evenly over the previously cleaned glass plate. The superfluous liquid is flowed off, and the film dried either spontaneously or by slightly warming. The film is generally dry in a few minutes, when it is rinsed with water, and again dried; at this stage the plate bears an open, porous film, slightly opalescent--so slight, however, as only to be observed by an experienced eye.

_Application of the Sensitive Film_.--We now come to the second stage of the process, the application of a film of bichromated gelatine to the plate.

Herr Löwy's formula is as follows:

Bichromate of potash. 16 grammes.
Gelatine. 2½ ounces.
Water. 20 to 22 "

According to the weather, the amount of water must be varied; but in any case the solution is a very fluid one. An ounce is about 35 grammes, as most of our readers know. A practical collotypist sees at a glance the quality of the prepared plate, without any preliminary testing. A good preliminary film is a glass that is transparent, yet slightly dull; the film is so thin, you can scarcely believe it is there. The plate is slightly warmed upon a slate slab, underneath which is a water bath; it is then flooded with the above mixture of bichromated gelatine, leaving only sufficient to make a very thin film. When coated, the plate is placed in the drying chamber.

_Drying the Sensitive Film_.--Much depends upon the drying. A water bath with gas burner underneath is used for heating, and a slate slab, perfectly level, receives the glass plate. The drying chamber is kept at an even temperature of 50° C.

The object to be attained is a fine grain throughout the surface of the gelatine, and unless this grain is satisfactory the finished printing block never will be. If the gelatine film be too thick, then the grain will be coarse; or, again, if the temperature in drying be too high, there will be no grain at all. The drying is complete in two or three hours, and should not take longer.

_The Negative to be Printed from_.--The sensitive film being upon the surface of a thick glass plate, it is necessary that the cliché or negative employed should be upon patent plate, or not upon glass at all, so as to insure perfect contact. Best of all, is to employ a stripped negative, in which case absolute contact is insured in printing. It is only in these circumstances that the most perfect impression can be secured. If the negative is otherwise satisfactory, and only requires stripping, it must be upon a leveling stand, and fluid gelatine of a tolerable consistence is poured over it. When dry, a pen-knife is run around the margin, and the film leaves the glass without any trouble.

Herr Obernetter says that many of the negatives he receives have to be reproduced before they can be transformed into Lichtdruck plates, and he employs either the wet collodion process or the graphite method, according to circumstances. If the copy is desired to be softer than the original, collodion is employed; if vigor be desired, graphite is used, and here is his formula:

Dextrine. 62 grains.
Ordinary white sugar. 77 "
Bichromate of ammonia. 30.8 "
Water. 3.21 ounces.
Glycerine. 2 to 8 drops.

The film is dried at a temperature of 130° to 140° F. in about ten minutes, and while still warm is printed under a negative in diffused light for a period of five to fifteen minutes. In a well-timed print the image is slightly visible; the plate is again warmed a little above atmospheric temperature in a darkened room, and then fine levigated graphite is applied with a fine dusting brush, a sheet of white paper being held underneath to judge of the effect. Breathing upon the film renders it more capable of attracting the powder. When the desired vigor has been attained, the superfluous powder is dusted off, and the plate coated with normal collodion. Afterward the film is cut through at the margins of the plate by means of a sharp knife, and put into water. In a little while--from two to five minutes--the collodion, with the image, will be detached from the glass; the film is at once turned over in the water, and brought out upon the glass plate. Under a soft jet of water any air-bubbles that may exist between the collodion and the glass are removed, and then a solution of gum arabic (two grammes of gum dissolved in one hundred grammes of water) is poured over, and the film is allowed to dry spontaneously.

_Exposure of the Printing Block under the Negative_.--The exposure is very rapid. Any one conversant with photolithographic work will understand this. At any rate, every photographer knows that bichromated gelatine is much more rapid than the chloride of silver he generally has to do with.

There is no other way of measuring the exposure than by the photometer or personal experience, and the latter is by far the best.

After leaving the printing frame, the plate is immersed in cold water. Here it remains at discretion for half an hour, or an hour; the purpose, of course, being to wash out the soluble bichromate. It is when the print comes out of this bath that judgment is passed upon it. An experienced eye tells at once what it is fit for. If it is yellow, the yellowness must be of the slightest; indeed, Herr Furkl (the manager of Herr Löwy's Lichtdruck department) will not admit that a good plate is yellow at all. A yellow tint means that it will take up too much ink when the roller is passed over it. The plates of Herr Obernetter, however, are rather more yellow than Herr Löwy's--certainly only a tinge, but still yellow; and Herr Obernetter's work proves, at any rate, that the yellowish tinge is by no means inseparable from good results.

The washed and dried plate should appear like a design of ground and polished glass. The ground glass appearance is given by the grain. If there are pure high-lights (almost transparent) and opalescent shadows, the plate is a good one.

_Printing from the Block_.--We have now a printing-block ready for the press. If it is to be printed by machinery--that is to say, upon a Schnell press--the surface is etched; if it has to be more carefully handled in a hand press, etching is rarely resorted to; it is moistened only with glycerine and water. To etch a plate for a Schnell press, it is placed upon a leveling stand, and the following solution is poured upon it:

Glycerine............................. 150 parts.
Ammonia................................ 50 "
Nitrate of potash (saltpeter).......... 5 "
Water.................................. 25 "

Another equally good formula, recommended by Allgeyer, who managed Herr Albert's Lichtdruck printing for some years, is:

Glycerine............................. 500 parts.
Water................................. 500 "
Chloride of sodium (common salt)...... 15 "

In lieu of common salt, 15 parts of hyposulphite of soda, or other hygroscopic salt, such as chloride of calcium, may be employed.

The etching fluid is permitted to remain upon the image for half an hour. During this time, by gently moving the finger to and fro over the surface, the swelling or relief of the image can be distinctly felt. The plate is not washed, but the etching fluid simply poured off, so that the film remains impregnated with the glycerine and water; at the most, a piece of bibulous paper is used to absorb any superfluous quantity of the etching fluid. After etching, the plate is taken straight to the printing press. The inking up and printing are done very much as in lithography. If it requires a practiced hand to produce a good lithographic print, it stands to reason that in dealing with a gelatine printing block, instead of a stone, skill and practice are more necessary still. Therefore at this point the photographer should hand over the work to the lithographer, or rather the Lichtdruck printer. It is only by coaxing judiciously, with roller and sponge, that a good printing block can be obtained, and no amount of teaching theoretically can beget a good printer. To appreciate how skillful a printer must be, it is only necessary to see the imperfect proofs that first result, and to watch how these are gradually improved by dint of rolling, rubbing, etching, cleaning, etc. In all Lichldruck establishments, two kinds of rollers are used, viz., of leather and glue. In some establishments, too, they employ two kinds of ink; but Herr Löwy manages to secure delicacy and vigor at the same time by using one ink, but rolling up with two kinds of roller.

Collotype printing is not merely done by hand presses, but is also done by machinery. At Herr Albert's a gas engine of six-horse power is employed to drive the machines, and each machine requires the attention of a skilled mechanic and a girl. The press is very like the lithographic quick press. Upon a big steel bed lies the little collotype block. The glass printing block, with its brownish film of gelatine, moves horizontally to and fro, and, as it does so, passes under half a dozen rollers, which not only supply ink, but disperse it. Some of the rollers are of leather and others of glue, and, whenever the printing block retires from underneath them, an ink slab takes the place of the block, and imparts more ink to the rollers; sometimes as many as eight rollers are used, for the difficulty of machine printing is to apply the ink as delicately and equally as possible. It is necessary at intervals to damp the block, and when the printer in charge finds this to be the case, he stops the press, and applies a little glycerine and water with a cloth or sponge; then a leather roller is passed over to remove superfluous moisture, and the press is again started.

Herr Obernetter relies upon the Star or Stern press--a small lithographic press--one man sufficing to manage it, who turns a wheel with large spokes, reminding one of the steering wheel of a ship. The Lichtdruck plate, gelatine film upward, is laid upon a sheet of plate glass by way of a bed, the plate having first been treated with a solution of glycerine and water; it is then inked up as previously described, except that Herr Obernetter uses two kinds of ink--a thick one and a thin--applied by two rollers of glue. In the first place, a moist sponge is rubbed over the surface; then a soft roller covered with wash-leather, and of the appearance of crêpe, is passed over two or three times to remove surplus moisture; then a roller charged with thick ink is put on, and then another with thin is applied. It takes fully five minutes to sponge and roll up a plate, the rolling being done gently and firmly. A sheet of paper is now laid upon the plate, the tympan is lowered, and the scraper adjusted with due pressure; a revolution of the wheel completes the printing, the well-known scraping action of the lithographic press being used in the operation.

Some Lichtdruck prints are printed upon thick plate-paper, and are ready for binding without further ado, these being for book illustrations. Other pictures, that are to pass muster among silver photographs, are, on the other hand, printed upon fine thin paper, and then sized by dipping in a thin solution of gelatine; after drying, they are further dipped in a solution of shellac and spirit.--_Photo. News_.

* * * * *

DOMESTIC ELECTRICITY.

Among the most valuable, and, up to the present time, the least generally appreciated services that electricity can render for domestic purposes is that of its application in lighters. At the present epoch of indifferent matches, to have, instantaneously, a light by pulling a cord, pressing on a button, or turning a cock, is a thing worthy of being taken into serious consideration; and our own personal experience permits us to assert that, regarded from this point of view, electricity is capable of daily rendering inappreciable services.

According to the nature of the application that is to be made of them, the places in which they are to be put, and the combustible that they are to inflame, etc., electric lighters vary greatly in form and arrangement.

We shall limit ourselves here to pointing out the simplest and most practical of the numerous models of such apparatus that have been constructed up to the present time. All those that we shall describe are based on the incandescence of a platinum wire. A few have been constructed based on the induction spark, but they are more complicated and expensive, and have not entered into practical use. Before commencing to describe these apparatus, we shall make a remark in regard to the piles for working them, and that is that we prefer for this purpose Leclanché elements with agglomerated plates and a large surface of zinc. In order to bring about combustion in any given substance, it is necessary to bring near it an incandescent body raised to a certain temperature, which varies with the nature of the said substance, and which is quite low for illuminating gas, higher for petroleum, and a white heat for a wax taper or a candle. We have said that we make use exclusively of a platinum wire raised momentarily to incandescence by the passage of an electric current. The temperature of such wire will depend especially upon the intensity of the current traversing it; and, if this is too great, the platinum (chosen because of its inoxidizability and its elevated melting point) will rapidly melt; while, if the intensity is too little, the temperature reached by the wire will itself be too low, and no inflammation will be brought about. Practice soon indicates a means of obviating these two inconveniences, and teaches how each apparatus may be placed under such conditions that the wire will hardly ever melt, and that the lighting will always be effected. For the same intensity of current that traverses the wire, the temperature of the latter might be made to vary by diminishing or increasing its diameter. A very fine wire will attain a red heat through a very weak current, but it would be very brittle, and subject to break at the least accident. For this reason it becomes necessary to employ wires a little stronger, and varying generally from one to two-tenths of a millimeter in diameter. The current then requires to be a little intenser. The requisite intensity is easily obtained with elements of large surface, which have a much feebler internal resistance than porous-cup elements; and since, for a given number of elements, the intensity of the current decreases in measure as the internal resistance of the elements increases, it becomes of interest to diminish such internal resistance as much as possible. The platinum wires are usually rolled spirally, with the object in view of concentrating the heat into a small space, in order to raise the temperature of the wire as much as possible. There is thus need of a less intense current to produce the inflammation than with a wire simply stretched out. In fact, the same wire traversed by a current of constant intensity scarcely reaches a _red_ heat when it is straight, while it attains a _white_ heat when it is wound spirally, because, in the latter case, the cooling surface is less.

We shall now proceed to the examination of a few practical forms of electric lighters.

In Fig. 1 will be seen quite a convenient spirit or naphtha lighter, which has been devised more especially for the use of smokers. By pushing the lamp toward the wall, the wick is brought into proximity with the spiral, and the lamp, acting on a button behind it, closes the current. Pressure on the lamp being removed, the latter moves back slightly, through the pressure of a small spring which thrusts on the button. Owing to this latter simple arrangement, the spiral never comes in contact with the flame, and may thus last for a long time. Mr. Loiseau, the proprietor of this apparatus, employs a very fine platinum wire, flattened into the form of a ribbon, and it takes only the current from a _single element_ to effect the inflammation of the wick. The system is so arranged that any one can easily replace in a moment the spiral that has accidentally got out of order; and, in order that this may be done, the maker has placed the spiral on a small, distinct piece that he styles the "conflagrator." The latter consists of two small, thin tubes of brass, held parallel and firmly by means of a brass cross-piece. A small bit of paper wound round each tube in front of the cross-brace insures insulation. The outer extremity of the two tubes supports the platinum spiral, which is fixed to them very simply by the aid of two small brass needles of conical form, which pinch the wire in the tube and hold it in place. There is nothing easier to do than replace the wire. All that is necessary is to remove the two little rods with a pair of pincers; to make a spiral of suitable length by rolling the wire round a pin; and to fix it into the tubes, as we have just explained. With two or three extra "conflagrators" on hand, there need never any trouble occur.

In Fig. 2 we show a new and simple form of Mr. Ranque's lighter, in which an electro-magnet concealed in the base brings the spiral and the wick into juxtaposition. The extinguisher, which is balanced by a counterpoise, oscillates about a horizontal axis, and its support carries two small pins, against which act successively two notches in a piece of oval form, fixed on the side of the movable rods.

In the position shown in the cut, on the first emission of a current the upper notch acts so as to depress the extinguisher, but the travel of the rods that carry the spiral is so limited that the latter does not strike against the extinguisher. On the next emission, the lower notch acts so as to raise the extinguisher, while the spiral approaches the wick and lights it. It is well to actuate these extinguishing-lighters, which may be located at a distance, not by a contact button, but by some pulling arrangement, which is always much more easy to find in the dark without much groping about. There might be used for such a purpose the very motion of the front door, when opened, for lighting the hall; but that would offer the inconvenience of operating likewise in the daytime, and of thus needlessly using up the pile and the naphtha. In all these spirit or naphtha lighters it is important that the spiral _shall not touch_ the wick, but that it shall be placed a little above and on the side, in the mixture of air and combustible vapor.

Several apparatus have likewise been devised for lighting gas by electricity, and a few of these we shall describe.

The simplest form of these is Mr. Barbier's lighter for the use of smokers, for lighting candles, sealing letters, etc. It consists of a small gas-burner affixed to a round box, seven to eight centimeters in diameter, and connected to the gas-pipe by a rubber tube. By maneuvering the handle, the cock is opened and an electric contact set up of sufficient duration to raise to a red heat the spiral, and to light the gas. It is well in this case, for the sake of economizing in wire, to utilize the lead gas-pipe as a return wire, especially if the pile is located at some little distance from the lighter. In the arrangement generally in use the key is provided with a special spring, which tends to cause it to turn in such a way as to assume a vertical position, and with a tooth, which, on engaging with a piece moving on a joint, holds it in a horizontal position as soon as it has been brought thereto. In order to extinguish the burner, it is only necessary to depress the lever, and thus allow the key to assume again the vertical position, that is to say, the position that closes the aperture through which the gas flows out. In a new arrangement, the notch, spring, and the lever are done away with, the cock alone taking the two positions open or closed.