In Paris a new kind of cuirass for the use of the army, is shortly to be tried. This cuirass is of vulcanized India-rubber, about half an inch thick. The thickness, it is stated, is more than sufficient to resist the action of a ball projected from any kind of firearm. All the experiments tried have proved entirely successful. The force of the ball is completely broken by the elasticity of the India-rubber, and it falls on the ground at the feet of the person against whom it was sent. NEW GUTTA-PERCHA COMPOSITION. Alfred H. Gaullie, Paris, patentee. This improved composition is formed by mixing together equal parts of gutta-percha and of Roman cement reduced to a pasty consistence with ox-gall. The operation of mixing is to be performed while the gutta-percha is in a heated and plastic state, and the two ingredients must be well masticated so as to cause them to combine intimately together. Any kind of coloring matter may be combined with the materials according to the effect desired to be produced. INDIA-RUBBER VARNISH. A. Ford, of London, has obtained a patent for making solutions of India-rubber and gutta-percha, which solutions can be used for water-proofing as a varnish. The India-rubber or gutta-percha, is dissolved in warm turpentine or naptha. The turpentine, or naptha, is prepared by mixing a caustic alkali, such as potash, in it—one pound to the gallon—then agitating them in a suitable vessel, and allowing them to stand for about three days, when a dark colored residuum is found at the bottom. The clear liquor is then poured off and used for dissolving the India-rubber. It is stated that this makes a very beautiful varnish. WATER-PROOFING OIL. A patent has been obtained by Alex. Parkes, of Bury Port, Wales, for a preparation of oils similar in its nature to the improvement of Mr. Daines. He treats oils with the chloride of sulphur, which changes their character, rendering them similar to vulcanized India-rubber, and insoluble in mineral naptha and sulphuret of carbon. He heats about 2 parts by weight, of the chloride of sulphur with 8 parts, by weight, of oil, up to about 250°, when the combination of the two is effected. This vulcanized oil, it is stated, can be mixed with gutta-percha or India-rubber, to cheapen the manufactured articles made from these materials. This, apparently, is also an important invention. Mr. Parkes has also taken out a patent for a varnish made of gun cotton dissolved in alcohol, or any solvent of gun cotton. This varnish is transparent, and he applies it to coat silk, sewing cotton, thread, leather, plaster, wood, &c., to render them water-proof. Gun cotton dissolved in chloroform is a well known varnish. INDIA-RUBBER TEETH.