80 HYDROMETALLURGY. [ill. 



being removed, when the peroxide is reduced to protoxide), 

 and so much iron introduced as is chemically equivalent to the 

 copper present in the water. In a few hours all the copper 

 is thrown down, and the liquid, passed through a cloth to 

 collect the copper, is evaporated to crystallize. (Rep. of Pat. 

 Inv. 1845.) 



Iron Coppered. — Reinsch has succeeded in giving to iron 

 a durable and polishable coating of copper, by immersing it, 

 after previous brightening by friction with cream of tartar 

 and charcoal-dust, in a bath of hydrochloric acid diluted with 

 o pts. of water, and containing a small portion of sulphate 

 of copper. After being immersed a few minutes, the iron is 

 removed, rubbed clean with a cloth, and again immersed. The 

 supply of copper must be renewed after each immersion, and 

 the immersion repeated until the coating is of the required 

 thickness. (Jahrb. Pr. Pharm. xv. and Liebig and Kopp's Rep.) 



Sulphuret of Copper, a coat for Copper Vessels. — R. Bottger 

 describes a bluish-gray coating, which gives a fine appearance 

 and protects from the weather. Dissolve 1 pt. of the crys- 

 tallized sulphantimoniate of sodium (sulphuret of sodium and 

 persulphuret of antimony) in 12 pts. water, heat to boiling, 

 and dip the well-cleansed copper vessel for a few moments 

 into the boiling solution. When the proper color is obtained, 

 the vessel is removed, well washed, and dried by a cloth. 



Coppering Glass, Porcelain, or Clay Vessels. — At the Ex- 

 hibition of Manufactures, in Berlin and Paris, in 1844, there 

 were vessels of glass, &c. coated with copper galvanically. 

 Dr. Mohr published (Dingler's Journ. Bd. 103, p. 364) a pro- 

 cess by which the coppering might be executed. He coated 

 the vessel with copal varnish, rendered the surface conductive 

 with gold-leaf, brass, or bronze-powder, and precipitated from 

 a solution of blue vitriol. The work was well executed, ex- 

 cept that, on heating a porcelain vessel thus coated, the copper 

 was loosed from it in the form of the vessel. Dr. Eisner pro- 

 posed another method (Verb. , d. Gewerbver. f. Preussen, 

 1847), which was not subject to the same defect. The surface 

 of the vessel was rendered matt or rough, by brushing on it 



