igo New EUSlrkal or Galvanic Apparatus. 



copper being precipitated in its metallic form by the wire connected with the filver. In 

 this inftance the metal did not cryftallize, but formed a kind of button at the end of the wire* 

 which adhered fo completely to the filver, that it was found impoflible to feparate it. 



The moft beautiful precipitate, however, was that of filver from its folution in the 

 nitrous acid. In this cafe, the metal fliot into fine needle-like cryftals articulated, or 

 joined to each other, as in the Arbor Dianse. 



What became of the oxygene gas ufually produced in thefc experiments ? 



Experiment 5. A quantity of pure water mixed with didiUed vinegar was introduced 

 Into the tube, and placed in the circle of communication ; fome gas was dlfengaged from 

 the filver wire, but no cloud appeared at the extremity of the zinc. After fome time, 

 however, a quantity of metallic filver was precipitated by the filver wire, and this precipi- 

 tate at lafl became very copious ; a perfe£tly fimllar efFe£t was produced, when the tube 

 was filled with very dilute fulphuric acid ; in ihefe cafes the precipitated filver had the ap- 

 pearance of (hining fcales, like that thrown down by copper in the ufual way. It may be 

 proper to obferve, that in all thefe precipitations and reductions, nothing but wires of 

 pure filver were employed. The refults in this lafl; experiment were exa£tly what was 

 expected ; the vinegar prevented the alkali from precipitating the filver, diffolved by the 

 generated acid ; in confequence of which, when a fuflicient quantity of the metal was 

 taken up, it was again thrown down by the filver wire in its metallic form. 



Experlmoit 6. A folution of the muriate of ammonia being introduced into the tube, 

 and expofed to this influence, a little gas was difengaged from the filver wire, while the 

 zinc one was Incrufled with a fubftance which foon became black, and was found to be 

 luna cornea. The liquor which remained in the tube after the operation had been finiflied, 

 was highly alkaline, and fmelled ftrongly of ammonia; common fait was dccompofed in a 

 fimilar manner. This experiment accounts for the decompofition of the muriate of foda 

 and ammonia, which always takes place when .the papers in the pile are moifliened with a 

 folution of thefe falts. 



A folution of the nitrate of magnefia appeared to be likewlfe decompofed by this procefs, 

 for after fome time, a white powder refembling magnefia, was precipitated on die furface 

 of the filver wire; very little gas was difengaged. 



Experiment 7. In order to afcertain how far this influence might be carried, provided 

 the circle of communication was complete, two tubes were employed, and connefted by a 

 filver wire parting through corks as in the figure, where A, B, reprefent the two tubes, and 

 C the conne£lion wire ; the tubes were filled with water and fecured by corks ; two other 

 wires D and E, being then pafled through thefe corks, the arc D was connected with the 

 filver, and the other with the zinc, at the extremity of the pile. A quantity of gas as ufual 

 was difengaged at the extremity of the filver wire D in A, and the portion of the conneifi- 

 ing wire C in the fame tube was partly diffolved, and as mentioned in experiment i ; but 

 the other portion of the fame wire in the tube B gave out gas, while the communicating 



zinc 



