The Optical Magic Lantern Journal (February 1897)

26 The Optical Magic Lantern Journal and Photographic Enlarger. The Lanternist’s Practical Cyclopzdia.*—No. IV. By CHARLES E. RENDLE. Brow-THrovucH Jer.—A jet of absolute safety, 80 constructed that a stream of oxygen passes through a flame of coal-gas, oxyhydrogen impinging on the lime cone.—See Blow-pipe. Biow-Pire.—A small instrument for directing a blast of air or other gas through a flame for the purpose of raising the temperature. The blow-through jet is but a double-tubed blow-pipe, where the combustible gas is directed through the outer tube, whilst the oxygen is blown through the flame from an inner tube. Biow-Pirz ANALYSIS.—A method in chemistry for the determination of the composition of minerals by the aid of the blow-pipe. Brose Virriot.—Sometimes called blue stone. Sulphate of copper. Bopy or Lantern. — The main casing to which the various accessories are affixed. Boruine Pornt.—The boiling points of liquids vary with the properties of the substance, some of the most volatile boiling at low temperatures, whilst others boil at very high temperatures. For example, ether will boil at 35° C. at normal atmospheric pressure, whilst mercury under the same pressure neccessitates a temperature of 350° C. The boiling point of water under normal conditions would be 100°C., cr 212° F., but as the boiling point is dependent upon the atmospheric pressure, the lesser the pressure the lessor the temperature, the greater the pressure the higher the temperature. So it may be assumed (con| sidering the approximation to be 1° C. for every 1,000 feet one rises), that ascending a mountain 6,000 feet the boiling point of water at that attitude would be 94°C., the air being much lighter at that height. Bone Brack.—See Charcoal. Borax.—A borate of sodium. Its substance, which is soluble in water, is whitish and of a sweetish taste. It is largely used in medicine, and as an uniting fluxin metallurgy. It is also used in photography, and in chemical analysis it is invaluable as a determining flux for certain metals, which becoming heated with it show out small globules of various beautiful colours. In addition to the above, borax is employed as a cleansing agent in many forms. Bxrass.—An alloy of copper and zinc.—See Copper. Brass Lacquer.—A varnish for metals, generally prepared by dissolving shellac in alcohol, when a colouring matter is added. A useful lacquer may be made by dissolving one ounce of shellac in twenty ounces of alcohol, to which add quarter of an ounce of dragon’s blood and about forty grains of turmeric root. If this be stored in a well-stoppered bottle it will keep for an indefinite period. When an article is to be lacquered it should be warmed to about 120° F., when the solution may be applied witha broad lacquering brush. BromIDEs.—The compounds of bromine with the metals are termed bromides. BronzE.—A tin and copper alloy, sometimes also containing zinc, iron, or lead in sma]l quantities. Bronze is harder than copper, more fusible, and may be rendered workable by frequent annealing, which is most effectively done by hating to a high temperature (dull *All rights reserved. redness), and suddenly cooled by plunging in cold water. If allowed to cool gradually it becomes hard and aia and in this particular is just the opposite to steel. BunsER BuRNER.—The common atmospheric burner in general use. Air is allowed to mix with the gas some distance from the point of ignition, rendering the flame smokeless and non-luminous. The advantages are principally greater heating power and economy. To one volume of gas consumed, about two volumes of air are used up in feeding the flame as fuel BURNERS FOR LanTERNS. — See Oxy-calcium Spirit Jet, Blow-through Jet, Combination Jet, etc., etc. CapEeNncy.—In rhetoric, the falling of the voice. Both in ordinary reading or speaking, the pitch of tone is termed the key-note, and by dropping the voice below that pitch is cadence.—See Elocution. CapMmiomM.—Many of the zinc ores contain traces of cadmium, It is a whitish metal much resembling tin in its properties and appearance, and although very malleable is tougher. Cadmia is a sulphide of cadmium. Catcium.—The metallic base of lime, a very light metal, one part being equal to one and a half parts of water. Yellow in colour, exceptionally ductile, so much so that it may be cut with a knife, or beaten out as thin as gold-leaf, its chief compounds being the oxide, the carbonate and the sulphate. Catcic.—Being in part calcium, containing calcium. CaLoTyPE.—A name given to a photographic process in 1840 by its inventor Henry Fox Talbot, and by its means pictures of natural objects and other things were obtained by the action of light upon nitrate of silver. The Calotype, however, like its predeceesor the Daguerreotype, has long since been superseded by other photographic improved advances. CameRrA.—The light-tight box or cabinet, containing an aperture or passage for the admission of light, and into this gapis fixed the lens which can be opened and closed at will. There are many varieties of camcras, but the principle in all isthe same as it was fifty years ago. The earliest was what is known as the old box pattern, consisting of one box working or sliding within another. Many of the original form are still about, and may frequently be seen in second-hand shop windows, or at sea-side resorts in summer time, and strange to say, it was some fifteen years before any departure was made in the pattern. The flexible body, or leather bellows was then introduced, and at once became popular in consequence of its light and portable nature, and although it is just over forty years ago since that change, it is with us to-day, and will remain without doubt practically unaltered through some generations. With the introduction of the bellows body, other inventions followed, some excellent, some useless. The rising front and swing-back attachments are strongly recommended, and all cameras to turn out good work should be fitted with these two at least. Of hand cameras (which by the way have proved a boon to the tourist and lanternist alike) much might be written; they are all more or less complicated in their automatic working, and the simplest that can be found is the best, which ever that may be out of such an endless variety. Negatives may be made on glass, celluloid films, or rolls of films, according to the make of camera. To thé tourist, or perhaps cyclist, who has to carry a camera of any dimensions, the celluloid films should be a@ great advantage when the difference in weight between glass and celluloid is considered.