3378. To Soften Brass

3378.    To Soften Brass. Heat it to a cherry red, and plunge it into water.

3379. To Cover Brass with Beautiful Lustre Colors

3379.    To Cover Brass with Beautiful Lustre Colors. Dissolve 1 ounce cream of tartar in 1 quart boiling water; then add 1/2 ounce protochloride of tin dissolved in 4 ounces cold water. Next heat the whole to boiling, and decant the clear solution from a trifling precipitate, and pour, under continual stirring, into a solution of 3 ounces hyposul-phate of soda in 1/2 pint water, then heat again to boiling, and filter from the separated sulphur. This solution produces on brass the various lustre colors, depending on the length of time during which the articles are allowed to remain in it. The colors at first will he light to dark gold yellow, passing through all the tints of red to an iridescent brown. A similar series of colors is produced by sulphide of copper and lead, which, however, are not remarkable for their stability; whether this defect will be obviated by the use of the tin solution, experience and time alone can show.

3380. To Put a Black Finish on Brass Instruments

3380.   To Put a Black Finish on Brass Instruments. Make a strong solution of nitrate of silver in one dish, and of nitrate of copper*in another. Mix the two together, and plunge the brass in it. Now heat the brass evenly till the required degree of dead blackness is obtained. This is the method of producing the beautiful dead black so much admired in optical instruments, and which was so long kept a secret by the French.

3381. To Frost Watch Movements

3381.    To Frost Watch Movements. Mix together 1 ounce each muriatic acid, nitric acid, and common salt; immerse the article, as far as it is to be frosted, in the mixture for a short time; then immerse it, so as just to cover it, in sour beer, and scour it under the beer with a brush made of fine brass wire (a scratch brush); wash it in water, and afterwards in alcohol. The surface is then ready to gild or silver-plate if desired.

3382. To Color Brass

3382.    To Color Brass. Although no alloy presents a more agreeable appearance to the eye than brass when it is in a high state of polish, yet the facility with which it tarnishes has rendered it necessary to color or bronze it, especially in those instances where its use exposes it to the liability of being frequently handled. The following receipts are from a reliable German source, and are said to possess a high degree of permanence. (See Nos. 3771, etc..)

3383. To Give Brass an Orange Tint

3383.     To Give Brass an Orange Tint. An orange tint, inclining to gold, is produced by first polishing the brass and then plunging it for a few seconds into a neutral solution of crystallized acetate of copper, care being taken that the solution is completely destitute of all free acid, and possesses a warm temperature.