56 AS X UAL RECORD OF SCIENCE AND INDUSTRY. 



now likely to come into practical use in European and Amer- 

 ican art. The existence of such a substance has long been 

 known from specimens of very ancient origin, and from its 

 use by the Chinese in the construction of their tom-toms. It 

 may be prepared from bell-metal bronze, to which twenty per 

 cent, of tin has been added, and heating to a dark red. This 

 generally brittle metal thus becomes malleable, and can be 

 readily forged and rolled out from a thickness of three or 

 four millimetres to that of a half to a quarter of a millimetre. 

 In the operation the density of the metal is increased, and it 

 can be welded easily, preserving its entire homogeneity. The 

 whole secret rests in giving the bronze the proper degree of 

 heat, since without this it remains brittle. 8 (7, xxvn.,e7w/y 

 6,214. 



COATING FABRICS WITH METAL. 



For the purpose of coating fabrics and tissues with metal, 

 such as copper, silver, and gold, the material is first to be im- 

 pregnated with a solution of sulphate of copper in ammonia, 

 and then dried. After drying, the whole is immersed in a 

 warm solution of grape sugar, which develops oxide of cop- 

 per, upon which silver or gold can be electroplated in the 

 usual way. 13 (7, 1870, 367. 



COATING ZINC WITH IRON. 



According to C. Puscher, of Nuremberg, zinc utensils may 

 be durably coated with iron in the following manner: Five 

 ounces of pure sulphate of iron and three ounces of sal am- 

 moniac are first dissolved in five pounds of boiling water, and 

 the objects to be treated immediately immersed. After from 

 one to two minutes, the loose black deposit is removed by 

 brushing it off with water. The principal effect of this opera- 

 tion is a perfect cleaning of the surface. The immersion in 

 the hot iron solution is then repeated, with the difference that 

 the objects when taken out are heated, without rinsing, over 

 a pan of live coals as long as the ammoniacal vapors are 

 evolved. When, after several immersions, the coating is con- 

 sidered thick enough, it is polished by brushing, and will ever 

 afterward be a perfect protection against oxidation. It im- 

 parts a fine black lustre to the coated surfaces. 14 G CC, 47. 



