GALVANIC EFFECT OF ZJNC AND COPPER IN WATER. 147 



II. 



On (lie Galvanic Tiffecl of very minute Particles of Zinc and Copper 

 in Water. In a Letter from Mr. William Wilson. 



To Mr. NICHOLSON. 

 S I R, London, Ocloier 11, 1802. 



1 WAS lately grinding fomefmall plates of copper upon fome Copper and zln# 

 plates of zinc (with fine emery), and after having wafhed them *?£ f™" d 

 in a cup of water to cleanfe them, I left them about five hours. The mud after 



When I returned I found the water in the cup covered with a fubfidence en "t- 



r ted gas j 



dirty froth, and upon taking up the cup to examine it, the agi- 

 tation caufed innumerable bubbles of air to rife from the fe.di- 

 mentat the bottom of the water. By continuing to agitate the and at remote 

 water for feveral minutes, they decreafed in quantity, and at ,ntervals * 

 laft difappeared. I now left it about four or five hours, and 

 then examined it again, when the bubbles were nearly as co- 

 pious as ever, and, with nearly the fame quantity of agitatioq, 

 again ceafed to be produced. 



I examined this water every four or five hours for five days, The effect lafte4 

 and the appearance was the fame, though weaker and weaker. five da y s * 

 After the fifth day I could not find that any bubbles were 

 generated ; I therefore (fuppofing this appearance to be occa- Copper and zin* 

 fioned by the particles of copper and zinc forming a kind of fi, . m 8 s weie 

 galvanic feries) took equal quantities of filings of copper and 

 zinc and put them into a glafs of water, and flirred it about to 

 mix them as much as poflible. In about three hours afterwards 

 there were fome bubbles of air adhering to the filings, which 

 by agitation rofe to the top of the water ; and the fame pheno- with the fame 

 menon was repeatedly exhibited. In fhort thefe metallic par- effe<a * 

 tides acted precifely fimiiar to the former, with only this differ- 

 ence : It required more violent agitation ; the air bubbles were Explanation of 

 larger, and the property difappeared much fooner, for there the dlfference " 

 were no bubbles generated after the third day. This differ- 

 ejice I fuppofed to be owing to the difference in thefize of the 

 particles of the metals ; for in the firft cafe the particles, by 

 reafon of their fmallnefs, would form a more numerous feries 

 and extenfive furface of contact, than the filings could in the 

 latter. 



L2 Laftly, 



