Chemico- Galvanic Observations. 13<) 



«pon metals and their oxides, that the former combined with 

 hydrogen, and that the latter returned to the metallic state 

 by the action of the negative side of the pile. He attributes 

 this last effect to the more powerful affinity of the origi- 

 nating hydrogen. But the black oxide of manganese forms 

 an exception. When it is galvanized in water negatively, 

 no gas is disengaged ; the oxide is not reduced ; it does not 

 become white, but it is united to hydrogen. One of the 

 characters which distinguish it is the positive property which 

 it acquires compared with oxide of manganese, which has 

 not been submitted to this operation. 



§ x. 



Disengagement of an, Alkali in distilled Water hj the Con~ 

 tact of a single Metal, without the Electrometer Appa- 

 ratus. 



In the course of his experiments upon the galvanization 

 of metals in pure water, and upon the influence of metals 

 upon water, independently of the action of the pile of Volta, 

 the author never remarked that water acquired acid proper- 

 ties by any contact, however long, with any given metal. 



We know that zinc and iron decompose water at e very- 

 temperature. The author placed fragments of each of these 

 two metals in two separate phials with a volume of distilled 

 water double their bulk ; he left them in contact with this 

 liquid until the decomposition had reduced it to two-thirds 

 of its volume. The metals were sensibly oxidated ; a oreat 

 deal of hydrogen was disengaged ; but the water underwent 

 no sensible change. 



He afterwards poured two ounces of distilled water upon 

 live ounces of zinc, in small pieces, contained in a phial of 

 eight ounces capacity, closing it with a ground stopper. 

 He agitated the mixture strongly for a quarter of an hour. 

 The water became muddy, and deposited a gray powder. 

 It was agitated again for nearly five hours with little inter- 

 ruption ; the quantity of gray powder was much augmented. 

 The muddy water was decanted, and allowed to settle. It 

 had a particular smell and a fetid taste. But what most sur- 

 prised the author was, that it greened the spirituous tincture 



of 



