332 On the Decomposition of Water. 



That of lead imitates the appearance of fern leaves; and upon 

 the ramifications of tin 1 have often seen, by means of the 

 lmgniivir.^ilass, octaedral crystals. It is remarkable that 

 the arborisation is always directed from the negative pole 

 towards the positive pole, whatever is the position of the 

 two poles, and it is consequently always established in the 

 track of the electrical current. The vegetation of a metal, 

 with the assistance of electricity, seems to imitate, in some 

 measure, that of the natural plants, which constantly incline 

 towards the light, disengaging oxygen by coming in contact 

 with the solar rays. 



VIII. When the metallic tree has extended within a short 

 distance of the positive pole its increase is stopped, because 

 its foliage, being infinitely slender in every respect, annihi- 

 lates the electrical action by exercising the power of an in- 

 finity of points. It even seems, that by the too near ap- 

 proach of the poles, each may acquire the electric fluid from 

 the other; for the extremities of the metallic ramifications 

 have sometimes begun to oxidate while deoxidation was 

 manifested in the positive pole. It is probable that always 

 when the extremities of the two conductor wires become 

 very slender and very nearly approach each rtthi r in the. 

 water, the gases coming from their decomposition are mixed 

 one with another. Here we have, if I am not mistaken, an 

 analogy between the decomposition of water by an electrical 

 machine, and that which is effected by the pile of Volta*. 



IX. When the current of Galvanic elect] icity acts upon 

 water either pure or when charged with some soluble sub- 

 stance, the positive pole attracts the oxygenating principle, 

 while the negative pole attracts the oxygenated principle of 

 the liquid. If the proportion of the components of the 

 latter is variable, it becomes oxygenated at the extremity of 

 the wire in communication with the disk of zinc, and de- 

 oxygenated at the extremity of the wire in contact with the 

 disk of copper. The following arc the proofs of this fact: 



J VVolIaston, upon decomposing water by the electricity of an ordin - v 

 jnachine, constantly observed that the o> land the hydrogen were disen- 

 gaged both at once, while the action of the pile inclines them to show them* 

 selves separately. 



X. The 



