EFFECT OF GALVANISM IN METALLIC ARBORIZATIONS. J ]§ 



immediate superposition of the metallic particles on the by addlHons 

 ramifications most remote from the fine. Suppose om to ^jii^^**"** 

 be a particle of oxide of lead in the lower part of the solu- 

 tion, not yet decomposed, and very nea^ the ramifications: 

 the moment the metal, m, is deposited on them, itsoxigen,o, 

 is consequently set free, and the oxidation of the zinc, t, at 

 the same time goes on. Now it remains to be known, 1st. Questions, 

 whether this atom of oxigen, o, be immediately seized by 

 some peculiar impulse, that carries it through the liquid from 

 m tor; and, 2ndly, how it is transported thither without 

 any appearance of )^as ; or, 3dly, what becomes of it, if it 

 be not moved out of its place. It would be absurd to sup- Untenable 

 pose, that the oxide of lead, fno, came into contact with the suppoiition, 

 zinc, z ; and that the metal, m, after having yielded to it its 

 oxigen, o, descended from z to m ; since, m proportion as 

 the arborization takes place in such a narrow tube, the 

 superior part of the liquid no longer contains any lead, but 

 acetate of zinc. Yet, as it would be easy to conceive some 

 kind of flux and reflux, or to invent any other hypothesis, 

 I will endeavour to obviate such suppositions by a decisive 

 exj)eriment., without entering into any tedious discussion. 



If a tube, a b, fig. 8, be filled with a solution of muriate Expeiimeau 

 of tin diluted with water ; and a little cylinder of zinc, Zy • 

 he placed at the bottom of the tube ; the arborization will 

 go on regularly, often to the height of an inch or more, if the 

 liquid be of a proper density. It is not till after these first 

 rudiments of an arborization have taken place, that the 

 difi^erent branches, crushed by their own weight, fall down, 

 and exhibit a confused heap of metallic ramifications. 

 The tree of Diana too grows very regularly from the bottom SiWer tree. 

 upwards, but this symmetry is essential, and th^ precipita- 

 tion of the metal by superposition is sufficient to establish two 

 propositions; namely, first, what becomesoftheoxigen of the propositions to 

 metallic particles, that are deposited on the extremities of the ^e ansirored. 

 tree farthest from the zinc? and, !2dly, what becomes of tb«! 

 disoxigenized |>rinciple, at the place where it yields its oxi- 

 gen to the. zinc*? These two questions offer theipseives in 



• We shall see pr<'semly, thai, almost immpdiMely a^'ter the arborifa- 

 •tlon of the dissolv.d raeia\ has commenced, notlung more is dejiosited 

 about the zinc, which noiw.thstanding coniimi«« tg be axidedj bat all 



YOL. XXVIII. FliB. 1811. 1 All 



