Before attempting to clean or repair old copper and brass curios or those objects which are made all or in part of either of them or of any of their alloys, it is well to know something of the constituents of the metals usually met with. First on the list comes ancient bronzes composed mainly of copper and tin on no accepted formula, but generally in the proportion of about three to one. Modern statuary bronze is made in several proportions; one compound is given by an authority as copper, 83 parts; tin, 5 parts; zinc, 10 parts; and lead, 2 parts; and by another as copper, 91 parts; tin, 9 parts. Bronze ornaments are mostly copper, 80 parts; tin, 3 parts; zinc, 15 parts; and lead, 2 parts. Gongs are of copper, 80 parts; and tin, 20 parts--some Oriental alloys have a little silver added. The ormolu of the brassfounder, used extensively by French metal-workers, has more copper and less zinc than brass. Red brass consists of copper, 25 parts; zinc, 5 parts; and bismuth, 1 part. Yellow brass is made of copper, 35 parts; and zinc, 15 parts. Pinchbeck metal, of which watchcases and jewellery have been made, consists of copper, 10 parts; and of zinc, 2 parts. Antimony imparts a rich red to copper. * * * * * In the following paragraphs some very useful "wrinkles" are given: Cleaning Copper and Brass. It is scarcely necessary to warn the collector against over cleaning, for to rub light bronzes which age has toned or encrusted with a beautiful patina would be vandalism indeed. Yet there are many objects which require attention when they arrive from the auction mart or curio-shop. Ancient bronzes should be washed in soap and water with soft brush or flannel--not scrubbed--and then dried in hot sawdust. If any polishing is necessary, a chamois leather or an old silk handkerchief will be sufficient. The green patina or verdigris of antique metals should _not_ be removed nor its colouring spoiled with cleaning. Copper vessels, however, do very frequently require cleaning. When they have turned a bluish green--not the much admired patina--they may be cleaned by making a paste of well powdered chalk and methylated spirit. This preparation should be rubbed on and then left until the spirit has evaporated and the chalk is quite dry, at which stage it can be removed and the copper polished with crocus powder or fine chalk. Owing to long neglect there are some metal curios which cannot be thoroughly cleansed without a powerful solvent. A weak solution of oxalic acid may be safely applied with a piece of woollen material; it will remove the tarnish, and then, after well washing, the metal can be polished with fine chalk or whiting. When the brass is spotted with damp but not too deeply marked, chalk and spirits of turpentine will generally effect the purpose just as well.