Take a solution of aqua-fortis in water, apply it to the black, and it will produce a beautiful scarlet.
424. BRUSH VARNISH
Take of spirits of wine 1 pint, gum benzion half a pound; dissolve the gum in the spirits. It may be laid on with a camel hair brush, or a small piece of wool rolled in old cotton.
425. TO BORE GLASS
Fill a vial with turpentine spirits, dissolve in it as much camphor as it will take, insert then into this liquid the point of a common diamond pointed drill, and with it you can bore glass as fast as you please.
426. GERMAN SILVER
Take of nickle 25 parts, zinc 25 parts, copper 50 parts, melt all together, and you have good german silver.
427. BRASS
Brass is made by melting together a little less than two parts of copper, and one part of zinc.