18 Quarterly German Magazine, 



copper, which is a combination of copper, oxygen and sul- 

 phuric acid, we obtain a blue liquid, which is so decomposed 

 through the current, that metallic copper secretes at the ne- 

 gative pole, while oxygen and sulphuric acid show themselves 

 at the positive pole. The copper encrusts thereby the nega- 

 tive pole with a layer which perfectly represents it in all its 

 protuberances and cavities, and which can be taken off after 

 it has attained a certain opacity. We then have an inverted 

 impression of the plate at the pole, on which every protuber- 

 ance is represented by an elevation and cavities by indenta- 

 tions. This is used to multiply medals and such things; an 

 impression of the object to be multiphed is taken in wax, 

 gutta percha and such hke, and then furnished with a con- 

 ducting cover, which in connection with the negative pole is 

 exposed to the influence of the electric current. The first im- 

 pression gives an inverted copy of the original object, a so- 

 called matrix \ the galvanic impression is, however, a true 

 imitation of the same. 



Corporeal objects, as busts, statues etc. can be copied in 

 this manner, which is called electro-metallurgy^ or ih.Q galva- 

 nic plastic art', a form is made over the body, consisting of 

 single pieces which are then set together, and a solution of 

 sulphate of copper is poured into the cavities, and then through 

 -the current the copper is precipitated on to the form. 



A second important appHcation of electro-metallurgy is 

 made in chalcography or the art of engraving on copper. A 

 great number of impressions cannot be taken from the copper- 

 plates which are engraved by artists, in consequence of the 

 phabiUty of their material, as the delicate Hnes suffer through 

 the pressure of the printing press. That is the reason, that 

 the first impressions, the so-called "epreuves d'artiste" and 



(UO) 



