This is a new, simple, and ingenious device for extinguishing lamps. The engraving shows plainly its method of attachment, and a few words will suffice to explain its operation. It consists of two small flat plates, one on each, side of the wick, attached to the right angular springs which hold them in the position shown in the engraving Rods with thumb- pieces at their outer ends pass through the metal work which supports the chimney, and abut against each spring at, or nearly at the angles. Pressure upon the thumb-piecCB— the thumb being placed on one, and the forefinger on the one opposite—forces the plates together, compressing the wick, and extinguishing the flame. Our rural friends will see the analogy between this operation and the old and long-practiced method of snuffing out a candle with the fingers. Patent pending through Scientific American Patent Agency For further information address Grayson and Hyndman, Odell 111. Coppering and Tinning Iron, Cast iron is easily coppered by simply immersing it in a solution of copper vitriol, but the coating of copper thus produced does not adhere to the iron. The copper will adhere to the iron when employing the galvanic current, chiefly when the cast iren had been previously coppered or immersed in a solution of cyanide of potassium and copper. The great advantages which would arise from the perfection of a plan by which iron could be coated with copper at a cheap rate, in-luced Messrs. Eisner and Philip, of Berlin, to undertake a series of experiments to ascertain if the coppering could not be effected more economically than by employing cyanide of potassium, and in this they have been successful. To coat iron the article must be well cleaned in rain or soft water and rubbed before immersion in the solution, which may be either chloride of potassium or chloride of sodium containing a little caustic ammonia added, or tartrate of potash, with a small portion of carbonate of potash. At the extremity of the wire, in connection with the copper or negative pole of the I battery, is fixed a thin flattened copper plate, and the article to be coated is attached to the wire from the zinc or positive pole, and both are then immersed in the solution, the copper plate only partially. The liquid should be kept at a temper- 1 ature of from 15 to 20 C, and the success of the operation depends on the strength and uniformity of the galvanic current. When the chlorides are employed, the coating is of a dark, natural copper color, and with tartrate of potash it as- Bumes a red tinge, he red oide of copper. When sufficiently covered, the article is rubbed in saw dust, and exposed in a current of warm air to dry, when the metal will take a fine polish and resist all atmospheric influence. A coating of tin is frequently applied to certain kinds of castings, chiefly to cooking utensils, thus preventing them from rusting, and also preserving the food to be cooked from taking a black tinge. The tin applied must be free from lead, or the food is liable to become poisoned. The articles to be tinned are first turned in a lathe, or otherwise well cleaned, and washed with dilute muriatic acid of 8 or 10 B., or with sulphuric acid. The articles are now dried and heated up to the melting point of tin; the fluid tin is then rubbed either with a cork, or a ball of cotton, on the bright surface of the iron to be tinned. Too low a temperature of the pots causes too thick a coating, and too high a tern perature prevents the tin from adhering to the iron. Sal ammoniac, or chloride of zinc and ammonium, is employed in the operation to keep the surface of the metal free from oxidation. The tinning of iron by Mr. Morris Stirling's patent process is thus described in lire's " Dictionary," vol. iii., p. 925, thus : " For this purpose the sheet, plate, or other form of iron previously coated with zinc, either by dipping or by depositing from solutions of zinc, is taken, and after cleaning the surface by washing in acids, or otherwise, so as to remove any oxide or foreign matter which would interfere with the perfect and equal adhesion of the more fusible metal with which it is to be coated, it is dipped into melted tin, or any suitable alloy thereof, in a perfectly liquid state, the surface of which is covered with any suitable material, such as fatty or oily matters, or the chloride of zinc, so as to keep the surface of the metal from oxidation, and such dipping is to be conducted in a like manner to the process of making tin plate or of coating iron with zinc." Tinned iron articles which are deficient in tin, oxidize more rapidly than iron without any tin coating, owing to a galvanic reaction caused by the contact of tin and iron. A coating of zinc, on the other hand, more effectually protects the iron from oxidation, even if this coating is only partial, but as zinc is readily dissolved in acids, salt brine, etc., iron vessels coated with it cannot be used for cooking purposes. Iron may also be coated with zinc by the galvanic current. —Practiced Treatise m Metallurgy by Crookes and Bohrig. INGROWING TOE NAIL.—Dr. Babb (Medical Times and Gazette) has used " with uniform success" in ingrowing nail, a saturated solution of the persulphate of iron. Success depends upon the thoroughness with which a bit of cotton saturated with it is insinuated between the nail and the fungous flesh, the cotton being also turned back over the flesh on the outside. ALL construction is limited and circumscribed by the fixed laws of nature. To violate these is to court ruin.