The true nature of a liquid .film is comparable to that of a perfectly elastic and tightly stretched membrane. All liquids are bounded and inclosed by such a membrane, composed of the substance of the liquid itself. The phenomena of films, under the form of soap bubbles, have been known for many generations. They were seriously studied by Sir Isaac Newton, and later by the scientist Dr. Plateau, of Belgium, a curions study for one, like the latter, afflicted with total blindness. If a ring one or two inches in diameter, and provided with a handle, is dipped into a solution adapted for forming films, and is withdrawn, it will be found to be filled with a beautiful film, straight and firm, reminding us of the wing of a dragon fly, Fig. 1. If we blow against it, it will be driven out into a purse-like shape of very characteristic outline (see dotted line). If it b6 held between the mouth and a candle, it-will ssreen the latter from strong blowing until it breaks, when the candle will be extinguished. By particular management a hole of any desired size can be made in the side of a soap bubble. This is done by tying a small loop, less than the third of an inch, in the end of a silk thread, moistening it thoroughly with the solution, and hanging it over the bowl of a pipe just before blowing a bubble. As the bubble is blown, the end of the thread and the loop will adhere to it. Then by touching the film within the loop, either with a hot wire or with a piece of blotting paper, the film will break inside of the loop, which will fly open to its widest extent, Fig. 2. The bubble will immediately collapse, or by vigorous blowing may just be kept inflated. The blast from the hole is sometimes enough to extinguish a candle. This. shows thll.t the film is elastic. To measure di- rectly the tension exerted by an inflated bubble, a glass tube bent at a right angle may be attached to the end of a pipe stem. After blowing a bubble, the end of the glass tube may be dipped into water, when the depression will show the pressure, Fig. 3. It will be but a small fraction of an inch. To measure the tension of the film per unit of surface, a little frame with grooved sides is employed. In the grooves a wire carrying a little scale pan slides freely up and down, Fig. 4. The wire is pushed home to the top of the frame and some of the solution introduced, either by dipping the top or by painting it in with a brush. Then by adding weights the film can be pulled down like a delicate curtain until the limit is reached, and it breaks. By mounting a ring as a pendulum and filling it with a film, Fig. 5, the retardation the latter exercises on its swing is quite striking. Four of the rings may be mounted as a windmill, Fig. 6, and be made to turn several times by the breath until their perishable sails break one by one. If a thread, well moistened with the solution, is laid across a ring containing a film, and the film is broken on one side of it, the thread will be suddenly snatched across the ring and be drawn up tightly against the opposite side. To facilitate manipulation, the ends of the thread may be fastened to the ends of a wire, or thin slip of wood. On drawing out the thread it will draw with it a curtain of film, and will assume the curve of the arc of a circle, Fig. 7. In this way the ring may be again filled with film and the thread be entirely removed. A bubble may be blown, a moistened ring touched to it, and the pipe pulled away, leaving the bubble adhering to the ring. The pipe may be again dipped, passed through the upper part of the bubble into its interior, and a second bubble may be blown thus in the interior of the first, Fig. 8. By catching a bubble on a ring, as described above, and touching it witli a second ring, previously moistened, it will adhere to both, so that it can be drawn out into the most elegant shapes, Fig. 9, reminding us of the iridescent glass vases so popular a few years ago. Again attaching a bubble to a ring, the a:ir in it can be drawn out by inverting the mouth of the pipe until, on pulling away the pipe, a lenticular bubble will remain, Fig. 10. The well known diffusion experiment with a porous jar can be very nicely shown with a film. The mouth of the jar, a porous cup of a BunEen or Daniell battery, drogen, or street gas, is inverted over it, Fig. 11. The lighter gas diffusing into the porous vessel blows a bubble from the film. On removing the outer ar the reverse action takes place, and the bubble collapses. Very pretty effects can be produced by blowing bubbles full of tobacco smoke. By attaching the pipe stem by a rubber tube to the gas fixture, they may be in flated with gas, when they will rise like balloons Many formulas have been published for making a good- mixture. Plateaus mixture is thus prepared: : part of Marseilles soap is dissolved in 40 parts of water at a moderate heat. It is filtered through very porous filter paper, after cooling, and 15 parts of the solution are mixed with 11 of Prices glycerine. The mixture is thoroughly shaken, and is allowed to stand for seven days in a room that is not too cold (over 67 Fah.). On the eighth day it is cooled for six hours to a temperature of 37 Fah., and filtered. A bottle of ice should be kept in the funnel. The first portions may need refil tering. Very porous paper must be used. Halbrooks brown oil silk soap or his Gallipoli soap, and Scheering & Glatzs glycerine work very well. The second filtration may be omitted—long standing and decantation from the sediment being used. After all the trouble the mixture may not give very good results. To succeed in these experiments a little practice and niceness i of manipulation is required, together with a good soap solution. How Window Glass Is Made. The workmen were engaged in making window glass, and proceeded in a way that seemed very simple. A young man would take one of the long hollow iron pipes we saw the gaunt man juggling with, and ap proaching one of the mouths of the great furnace with the indifference of a salamander—first,however, protect ing his face with a leather screen—would proceed by a series of wave-like movements of the pip/;l to gather at the end a ball of liquid glass, getting his supply from a fire clay pot. These pots contained a mixture of soda, lime, and itnd, which had been reduced by firing foi two days. After gathering a wad the size of a cocoa-nut, the y.oung man would turn and cool it upon an iron plate, still keeping up the wave-like rotary motion. Then he would return to the pot and begin fishing again, then back to the iron plate for cooling, and then more angling. By this time he has gathered a ball of about sixteen pounds weight and of intense heat. Now cooling the pipe with water, he carries his burden over and deposits it on a larger iron plate—this one floating in a tub of water—gives the pipe to a glass blower, and seizing another iron, goes back to the furnace to perform his part once again. The glass blower rolls the ball upon the plate until he- has made the glass assume a pear shape, when he applies the pipe to his lips and blows till his cheeks stand out like red apples, blows till he is red behind the ears; blows until he becomes of a complexion as blooming as the glass. All this while he imparts a rotary motion to the pipe, and does not cease either the blowing or the rotating until the pear shaped glass has expanded into the rude semblance to a bottle with no neck and a very thick bottom. Now over he goes to one of the mouths of the side furnace, into which he thrusts the pipe to warm the mean looking bottle at the end. At his feet is the grave-like pit. Now watch him. He takes the pipe from the furnace, blows in it, and lets it swing before in the pit. The glass begins to lengthen out, stove pipe fashion; into the furnace again; now out, and up over his head. Agitate the pipe.- Blow. Now a big sweep from mid-air through the pit and up again. Blow. Now a pendulum-like movement—up—down—way cross—back The glass is become a cylinder four feet long. Heat again and withdraw. Blow. Rotate. A little more jugglery —here—there—right side—left—a beautiful swing below The cylinder is over five feet long now The work is done These cylinders are placed still glowing on a stand. A tap with a piece of steel releases the blow pipe, the blower makes a measurement with a stick, wraps a string of hot glass about the cylinder, the superfluous part falls off as though cut with a diamond, and the completed cylinder—about five feet long and eighteen inches in diameter—is carried away to a place of safety. To-morrow a hot steel rod will cut each of the cylinders through one side, thus leaving it like a sheet of paper twisted until its upper and lower edges meet. This roll will be subjected to another gentle baking, when it will flatten out into a large sheet of glass. This will be cut into sheets of the proper size, and the work is done—M. Quad, in Detroit Free Press. The Medical Electric Lamp. The electric lamp used for examining General Grants ;hroat is manufactured by agents of the Edison Light Company. His mounted on a hard rubber holder, about seven inches long, having a reflector at the lamp end, by which the light can be thrown to any desired angle. The holder is connected by two silk-covered wires to a small storage battery carried in the pocket of the physician. The light is turned on by simply pressing asmall autton on the rubber holder, and the quantity is governed by another button convenient to the operator. The lamp is inserted in the mouth almost to the palate, with the reflector above the lamp, which throws the ight down the throat. The lamp has no unpleasant ieat, and gives a light equal to half a sperm candle. rhe extreme simplicity of the whole appliance makes t very valuable to the physician and dentist. A. New Japanese War Ship. On the afternoon of March 17, a cruiser built by Sir William G. Armstong, Mitchell & Co., being one of two begun less than twelve months ago to the order of the Japanese Government, was successfully launched from the shipbuilding yard of the company at Walker, in the presence of a large concourse of spectators. The Naniwa-Kan is the first of two powerfully protected cruisers which were begun at the Walker yard, about ten or eleven months ago. They were designed by Mr. W. H. White, intended for the swiftest and most heavily armed cruisers at present in existence. They are also the largest war vessels that have been hitherto built by the firm. During the last few years considerable activity has been displayed by the Japanese Government in connection with the development of their naval forces and the extension of their mercantil3 marine, a close connection existing between the two, and the merchantmen having been built so that some of the finest of them could be used as armed transports in case of war. As regards the distribution of the armament and their external appearance, the two new cruisers will bear a considerableresemblance to the famous Esmeralda. In fact, they may be briefly described as enlarged Esmeraldas, with substantial improvements in defense, structural arrangements, protection armaments, and speed, these improvements having become possible in consequence of the increase in size. In dimensions the new cruisers are almost identical with the Iris and Mercury, dispatch vessels of the Royal Navy, and the Leander class of partially protected cruisers. They are 500 ft. in length, 46 ft. in breadth, draw 18% ft. of water, and are of about 3,600 tons displacement. They have twin screw engines, which are to develop 7,500 H. P. at least, and their estimated speed is from 18 to 18% knots. The armament includes two 28 ton 26 centime-;er guns, mounted on center pivot automatic carriages is bow and stern chasers. These heavy guns are work-id and loaded by means of hydraulic mechanism, which s an improvement on that fitted in the Esmeralda. On ach broadside there are three 15 centimeter guns of ive tons each, also on center pivot automatic carriages f Elswick design, and along the broadsides there are ilso placed no less than ten 1 in. machine guns and two apid fire guns. There are two military masts, in the ;ops of which four of the improved Gatling guns made it Elswick will be mounted. All the guns, except those n the tops, are carried on the upper deck, and all of ;hem have strong steel shields protecting the gun -and irews from rifle and machine gun fire. Besides the gun irmament, each vessel will have a complete armament )f locomotive torpedoes, ejected from four stations, two n each broadside, situated at a small height above ater. Her powers of offense are further assisted by the pre-ience of a most powerful ram bow, formed of an im-nensely strong steel casting,which proj ects forward un-1er water,and would deliver a terrific blow upon the un-ler water portion of any of the ships attacked. The pow-srs of defense are also remarkably developed. Through-rat the length, and covering the spaces occupied by ma-hinery, boilers, magazines, and steering gear, there is a trong protective deck,the central portion of which rises i little above water, while the sides slope down to some lepth under water. This deck is of steel, and has a hickness varying from two to three inches; the total weight of the material used in this protection amount-ng to something over 450 tons. The few openings in his deck are protected by strong armored covers, or irmored gratings, and when the ship is ready for ,ction, and these openings are closed, the chance of hell fire reaching the vitals of the ship is extremely mall. In addition to the steel deck, the defense is as-isted by means of minute cellular subdivisions of the pace lying above the protective deck and below the lain deck, which is about six feet above water. In hese cellular subdivisions very large quantities of coal an be stowed, and when the coal is in the ship it will :reatly add to the defense. Below the protective deck n the hold there are also very large coal bunkers, from fhich can be drawn the supply of coal necessary for forking the ship for a considerable time when she is n action. Watertight subdivision is also carried out ery minutely in the hold space proper below the irotective deck. There are two separate engine rooms nd two separate stokeholes. The magazines are all uplicated and formed into separate watertight com-artments, and there is,a cellular dpuble bottom run-iing through a very lalge part of the length of the dip. This double bottom is fitted to be used for the stow-ge of water ballast, and in this manner the draught nd trim of the ship can be controlled as she consumes er coals, or ammunition and stores, so that whenever he has to fight, her protective deck can be brought ito proper relation to the water line. Moreover, the ellular bottom and the subdivision of the .hold space all add greatly to the . powers of the ship in resisting nder - water attacks by ram or torpedoes, or in pre-enting any serious consequences should the outer skin e damaged by grounding or other accidents. One ery notable feature in the Vessels is; the extremely rapid rate at which they have been built and their advanced state of completion at the time of launching, The openings in the funnel, hatches, and engine hatches have been so arranged that the machinery and boilers can be passed on into the vessels without disturbing the decks in the least, and consequently it has been possible to push on with the internal fittings of cabins, mess rooms, store rooms, etc., previously to the launch. The magazines, shell rooms, gun supports, and armament fittings generally are also in an exceptionally forward state, and the interval between the -launch and final completion of the ships will be proportionally shortened by the amount of work done while the vessel remains on the stocks. It may be questioned whether any war vessel of the size, and with the complicated fittings which are embodied in the design of the Naniwa-Kan, has been built in so short a time. The accommodations and fittings of the interior of the vessel are of an exceptionally good and finished character, and, besides having four powerful electric search lights, carried in commanding positions at bow and stern, each of the cruisers will also have internal electric lighting of the more important hold spaces. In every particular these vessels will embody the latest improvements in armament and equipment, and although they have been so rapidly constructed, it is but right to state that, in quality of workmanship and material, they will bear comparison with any war ships built in the royal dockyards. How to Make Cucumber Pickles. In the SCIENTIFIC AMERICAN of March 28, 1885, Answer? to Correspondents, No. 22, E. B. D. asks how cucumber pickles for the market are put up. Then follows a most extraordinary recipe, which, if followed would make each cucumber cost as much as Horace Greeleys turnips on his experimental farm—twenty-five cents apiece. For tblose who care to know how to prepare pickles (cucumbers) for the market or for home use, I give a couple of as good recipes as ever were practiced, and better than most that have been published. I know about what I talk on this subject from eleven years of practice. No. 1. Cucumbers for immediate use may be pickled by making a brine—a saturated solution of salt, all the salt the water will take up; cover the cucumbers with it, adding water if necessary. The brine will act sufficiently in one.night if poured on hot; if cold, give it twenty-four hours . Drain, and pack in a jarp,nd sca vinegar with cloves, cinnamon, and a lump of alum big as a marble for two gallons of cucumbers. Pour the spiced vinegar hot on the cucumbers and add a piece of horseradish root large as a human finger, and if desired two or three green peppers. These pickles are ready in three days, and with the horseradish will keep indefinitely. If the whole root of horse radish is not at hand, use some of the grated horseradish for the table. No. 2. For family use or the market, as occasion requires; pack the (jucumbers in salt, the coarse fine salt, is best, covering them properly. When needed for pickling, freshen them in water three days, changing the water twice, or four days if they are desired fresh, and add cold vinegar, spice if wanted, and the piece of horseradish. The Cotton Industries. The total number of spindles at the two different periods of 1870 and 1883 in operation in the great cotton manufacturing countries of the world is as follows: Great Britain. Continent. United States. Spindles. Spindles. Spindles. 1870 ..................... 34,000.000 18,300,000 7.100,000 1883..................... 42,000,000 21,215,000 12,660,00 The amount of cotton consumed by these countries from 181)0 to 1883 is as follows: Great Britain Continent United States. Bales. Bales. Bales. 1880................... 3,018,00 2,618,000 1,774.000 1881..................... 3,202,000 2,883,00 1,993.000 1882..................... 3,439,000 2,910,000 1,989,000 1883 .................... 3,426,000 3,447,000 2,231,00 Total............ 13,085,00 11,858,00 7,987,000 Average per year... 3,271,250 2,964,500 1,996,750 How Shall the Physician Cleanse His Hands? Dr. Forster, of Amsterdam, contributes an article on ;his subject to the Gentralblatt fur Klinische Mediein. He calls attention to the great importance of physicians ;horoughly disinfecting their hands before leaving It case of infectious disease (especially any of the exanthemata), and at the same time he asserts that few of the disinfectants now in use really have the power of destroying those microspores which are recognized as so langerous an element is modern medicine. After a series of careful experiments in the hygienic institute it Amsterdam, in which every precaution was taken to ivoid error, the author decided that a solution of car-aolic acid of the strength of two and a half per cent vas not capable of sterilizing the finger, but that a olution of corrosive sublimate of the strength of one o two thousand formed a reliable antiseptic wash. He irges that the latter be adopted by all phvsicians as veil as surgeons—N.Y: Med. Jour.