OALVAKIC PROCESSES, 95 



©f the pile, as in the experiment with water, is not acted 

 upon ; but the other is oxided in a much greater degree. 

 With my large apparatus (100 plates 92 square,) when I made 

 vise of brass wires in a solution of potash, the liquid in the 

 course of ten minuets became perfectly green with the copper 

 of the wire, and was rendered at the same time turbid with the 

 suspended oxide of zinc. 1 shall not at present say more on 

 this subject, as I mean in a future communication to give 

 some experiments on the action of galvanism upon bodies 

 dissolved in water. 



Mr. K., in his last paper, has made some assertions equally TFie evppri- 

 ^estitute of foundation. I am surprised at his giving lii"^- ani"narfibie 

 self the trouble of attempting to produce gas by using animal (instead of 

 and vegetable substances instead of metal. The rnoisture j^^^.''^^ ^^^"'^J^^^^" 

 contained in these bodies connected the liquid of the cell of explainetl. 



the trough with the glass of water, making them the same as"^''^ waters «;p 

 ^ ° ' o roiintviteQ are 



one vessel, IfMr. K.nad looked into the cell where one ccnridered as 

 end of this connecting substance was placed, he would have ^^^ *^'*^- 

 $een the gas upon the copper plate at the copper end, and the 

 y.inc oxided at the zinc end : so that the cells at the opposite 

 f-nd, the moist substances, and the water where these sub- 

 iiauccs terminated, were the same as one vessel, while the 

 terminating plates of the trough or pile performed the office 

 of the metallic wires. 



Mr. K. asserts that he had more gas when the w4res were Loagerwirps 



bnger. This I deny. He afterwards observes that an iron '^^ '^""^ '^^''^'^ 

 _ =• _ -^ luoro gas, ice. 



wire at the silver end of the pile " became brittle." If he 

 made use of a trough, and one end of the wire was immersed 

 lU the liquid oftlie cell, it would be oxided as far as the 

 liquid touched it, and might so far be brittle, but no farther. 



I have been lately engaged in a very interesting depart- Interestin:! ex- 



ment of chemistry which has been very much neglected, viz. P<^'"»'.'"'«"''*/« 

 . . . , . . . . precipitation 



tlie precipitation of one metal in solution by another in its of one nutai 

 solid form. The simple action of the piece of metal upon ^ another, 

 the oxide in solution is instlfficient to explain a namber of 

 very curious phenoniena attendant on some of these pro- 

 cesses. In the arbor diana? we see the appearance of vege- The precipita- 



taticn : and m the experiment with acctite of lead in a phial ^^" I" ^''^*/*''' 

 ' . '■ ^ oordiance takes 



With fi pieea of sine, we observe a bundle ot fine filaments place at the ex- 



of mcuul:^ lead reachingr to the bottom of the bottle. If a l'''^'^'''' <^f t''^ 

 ^ ^ branches. 



thin 



