482 TRANSACTIONS OF THE 



spiral strip of copper ; even tlien it sometimes breaks during the combus- 

 tion. A better plan would be to cover the tube with a coat of turpentine, 

 and sprinkle powdered plumbago over it, then connect one end of the com- 

 bustion tube with a copper wire, and plunge the whole into a sulphate of 

 copper cell, in the ordinary electrotype arrangement. In four hours the 

 tube will be found covered with a jacket of copper, and may be used with- 

 out the fear of accident, as it would matter little even if the glass broke, as 

 the tube would remain perfectly air tight ; the covering of copper is so ex- 

 ceedingly thin that the increased weight to a tube twenty inches long would 

 only be the one-tenth of a grain. 



A battery for electro-gilding and metallurgical purposes, maybe so con- 

 structed that the nitric acid can be replaced by the peroxide of lead, and 

 become capable, when charged with salt water, of decomposing water most 

 rapidly, and at the same time give off the gases separately. The great 

 practical advantage of substituting a peroxide for the nitric acid is, that 

 the battery may be charged with one liquid only. 



To decompose water with platinum electrodes, there must exist two 

 chemical actions in the pan of batteries, which will originate two currents, 

 and combine the effects, to wit : the reduction of the peroxide and the 

 oxidation of the zinc. 



I think the battery might be simplified by placing nitric acid in a plum- 

 bago vessel, this would bring the elements into an exceedingly close con- 

 tact, and probably be equal to a battery platinized containing the same 

 surface. 



A beautiful lace may be made by stretching a net of any material over 

 a copper wire frame, and cover it until perfectly black with plumbago. 

 Then connect it with the negative pole of a galvanic battery, and bring 

 voltaic action to bear, between two copper plates electrified positively, 

 which will, in a short ^:pace of time, cover each thread with a tube of cop- 

 per, which may be silvered or gilded, and used for ladies' fancy work. 



Electro deposition occurs when copper and zinc are bathed in a solution 

 of sulphuric acid. In the construction of the batteries for electro plating, 

 it is absolutely necessary to have a correct balance of power, or else, what- 

 ever may be exposed to the action of the metallic solution will present a 

 rough, instead of a smooth surface. >Yhen these matters are attended to, 

 articles may be immersed, and when withdrawn, will be found covered with 

 a thin coating of the metal used, before being dipped ; the article might be 

 considered worth five dollars, and after the process, to the eye, fifty, provi- 

 ded it was most thoroughly freed from grease and other impurities, by 

 boiling in caustic alkali, and rubbing with sand. Without this attention the 

 electro plating process would inevitably fail. 



By the old method, copper was the only available metal to plate upon, 

 but by the galvanic process, all metals are equally applicable. 



Nickel is white, and nearly the same density as silver. When this sub- 

 stance is plated with great care, and the union of the plating at the bottom 

 scientifically secured, it is almost impossible for any silversmith to indicate 



