The result is stated to be, iron filings, or fragments, in place of sand. that the mass has become so hard as to resist fracture, either with the hammer or pick-axe.
:I,substitute for gunpowder, J. Fournier the following curiosity : 125 grms. carbonate of lime ; 65 grms. salt ; 35 grms. of charcoal and as much wine as is ncccssa8ry to cover these materials in a vessel. The attention of our readers is invited, in this connection, to the very sensible remarks of Air. J. Richards upon the subject of patents. Surely no better argument for the necessity of thorough reformation of the system of patent laws could be desired than is aff’orded by the possibility of the committal of a blunder so glaring as the patenting of an “ invention ” so palpably and laughably absurd as this. A Novel Patent,--As
Welding Copper*.-A mixture composed of 355 parts of phosphnte of soda and 1.24 parts of boracic acid is recommended by XIr. Rust as a,ri admirable one to insure the perfect welding of copper. The powder should bc applied while the metal is at a dull red heat ; Owing to it is then brought to a cherry-red and at once hammered. the tendency of the metal to softtcn after exposure to a high Ii&, a wooden hammer is rccornmcnded which is to be applied very gently. All carbonaceous matter must be carefully removed from the faces to be joined, since the principle of the operation depends on the format.iou of :t very fusible phosphate of copper, which would be reduced The action of the subby carbon to the contlition of a pbosphide. stance recommended depends upon the ability of the phosphate of copper formed, to dissolve the thin film of oxide on the surfaces of metal, keeping them thus pcrfcctly clean and in condition to weld. A New Hygrometer:*\--&fr. Woodbury proposes to utilize the colorchanges which, as is well known to chemists, are produced in the chloride of cobalt on exposure to different degrees of moisture, For this purpose the for the purpose of hygromctric measurement. invent,or treats sized pa,per with a strong solution of chloride of cobalt., to which has been added R small quantity of common salt and gum arabic. This will retain a blue color in a dry atmosphere, but will change through all the gradations to pink, as the air becomes moist to damp. In order to construct a scale for reading these indications,the inventor draws on a card two circles, one considerably .: Am. Ex. and Review, Dec., 18’il. f Ruglish Mechanic, xiv, 302.