MANUFACTURE OF LENSES.—mdash;Alfred Vincent Newton, patentee.—mdash;The 'dioptric lens, here tofore in use, for sea lights or other lights re quiring great intensity, being constructed of single zones or rings, made up of segments according to the diameter of the required lens, has induced a belief that glass could not be prepared without incurring the expense of grinding and polishing the curved surface, and that economy dictated a method of manufac ture embracing a centre and zones or seg ments. The inventor was induced to exa mine the method of the construction of the built up lens, to try and reduce the expense without diminishing the strength of the light. Commencing with the suggestions of Buffon, that a spherical body from its thickness ab sorbs light according to its density, and that a sectional figure of any required shape and thickness could be cast of glass and ground in concentric cones, to produce a lens, as partial ly accomplished by Abbe Rochon, who pre pared the way for the manufacture of the di optric lens in separate pieces by the ingenious Fresnel, termed " the annular band lens," which is now used in our best lighthouses. These lenses are very expensive, for each se parate piece must not only have its surfaces formed with great accuracy, but all the sepa rate pieces must be arranged to each other, so that when put together they shall form a perfect whole. This invention is to produce a dioptric lens which shall present all the practical advantages of Fresnei's annular band lens, at so cheap a rate as to admit of its being applied to all purposes requir ing intensity.of light. The inventor makes dioptric lenses in one or several pieces mould ed and pressed into the form required for the surfaces, and when made in several pieces the required fit ot the several parts is produ ced by giving the reversed required form to metal moulds in which the molten glass is to be run and pressed. To promote focal inten sity, and prevent the absorption of light, each lens is manufactured as thin as the size and number of concavities and convexities will permit. [The above i3 from Newton's London Re pertory of Arts, Sciences, and Inventions ; al though the patentis in the name of Mr. New ton, the inventor, we believe, is a native of France. This improvement, if it answers ac cording to the expectations of the inventor, is one ot the most useful and important in ventions that has been brought before the public in many years. The ferry lanterns placed on our docks at night, are very ineffi cient, so are the lights carried in front of the wheel-houses on the boats. We hope and trust that such an invention as this one pur ports to be will be the means of leading our ferry companies, of which there are now a great many connected with this city—mdash;to adopt them. PURIFYING GAS —mdash;W. S. Losh, of Carlisle, patentee.—mdash;This improvement consists in em ploying the chloride of lead reduced to pow der and mixed with an equal bulk of coarsely powdered coke, or saw-dust, in order to allow the gas to move through it easily. These materials are mixed in a damp state, and laid upon the shelves of an ordinary dry lime pu rifier. The gas when passing through the chloride of lead and coke is deprived in a great measure of its ammonia and sulphurous components. Two such purifiers are used in conjunction, and when one ceases to act, the gas is turned on to the other. The chloride of lead can be brought back again for future use, by washing it, heating it to dryness, pass ing it through a sieve, and treating it with hy drochloric acid. SUGAR.—mdash;Joseph Brandies, London, paten tee.—mdash;This improvement consists in the use of the sulphurets and the hydrosulphurets of soda, potash, and ammonia lor precipitating 1 the lead used in refining saccharine solutions]! The sugar under treatment is to be dissolv ed in the usual way, and when about heated to 180 Fah., 1J per cent, of subacetate of lead is added and stirred in, and the solution is filtered. To the filtered liquor is then ad ded a sufficient quantity of hydrosulphuret, or sulphuret of soda, potash, or ammonia to precipitate every trace of the lead solution, which may be tested by hydrosulphuric acid. MALLEABLE IRON AND STEEL FROM CAST-IRON.—mdash;Jean E. Beauvelt, Paris, patentee.—mdash; This improvement consists in heating cast-iron in contact with metallic oxyde, or a car bonate containing a sufficient proportion of oxyde, and then rolling and hammering it without previous puddling. The cast-iron to be operated Jon should be cast into bars or plates in such a way that the bubbles and impurities may form the end bar or plate and be cut off with the rough end instead of being distributed over the surface. The substances used to change the character of the cast-iron are protoxyde of zinc and calamine, but the oxydes of iron, red oxyde of manganese, deu-toxyde of copper, protoxyde of tin, or oxydes of lead may also be employed. The protox yde of zinc, calamine, and oxydes of iron are the most suitable. The cast-iron bars are placed along with a sufficient quantity of the protoxyde or calamine in a common cement ing case, and are raised to a cherry red heat in a suitable iurnace, and kept at this heat till the process is completed. COATING FOR WOOD AND METAL.—mdash;Laurent Machabee, of Avignon, France, patentee.—mdash; This composition consists in melting together three and one-fifth of an ounce of vegetable tar, one ounce mineral tar, one-sixth oz. of white grease with the addition of one-third of an ounce of Roman and hydraulic cement re duced to fine powder. The latter ingredi-e ts are added to the others in a boiling state. This stuff in a hot state is applied to metal or brick surfaces with a brush. Any number of coats may be put on. The proportions given may be pounds, we only present the parts by weight. PAPER.—mdash;J. H. Brown, and J. Macintosh, of Aberdeen, Patentees.—mdash;This invention consists in using hollow moulds, composed of perfora ted metal, wire, or, other suitable material, and covered with felt, within which, after their immersion in a vat of pulp, a partial vacuum is created, so as to cause the pulp to adhere or be deposited on the felt surface in a layer of uniform thickness. This process is ap plicable to the manufacture of sheets of paper and various articles, such as envelopes, bags, cases, —c. The articles after having been formed, are subjected to a d rying process, and to pressure where their form will admit of it.—mdash; [London Mechanics' Magazine.
This article was originally published with the title "Recent Foreign Inventions"