334 On the Decomposition of JVater, 



sulphuric acid, assumes, in the cold, a fine blue colour, 

 which always disappears when heat is applied to the solu- 

 tion. Upon exposing it to the action of the pile of Volta, 

 the vitreous fluid acts in a manner analogous to heat, while 

 the resinous fluid produces an effect analogous to cold ; on 

 the positive pole the liquor becomes by degrees perfectly 

 transparent, and the molybdic acid is partly precipitated in 

 the form of a white powder, whereas round the negative pole 

 it always acquires a deeper and dirtier colour. Upon after- 

 wards changing the position of the two poles, so that the 

 one occupies the place of the other, the contrary happens j 

 the transparent part returns* to the blue colour, and the blue 

 part becomes transparent. 



XIV. When the Galvanic current exercises its influence 

 for a long time upon the solution of an earthy salt, the 

 base of the latter is gradually precipitated round the extre- 

 mity of the wire of negative electricity. These precipitates, 

 in my opinion, are not the effect of a decomposition by the 

 alkali which is generated at this point in an infinitely small 

 quantity ; but I presume that the acid of the salt is there 

 destroyed, or well decomposed, whence it results that its 

 earthy base becomes free. 



The glass tubes containing the solutions submitted to the 

 experiments I have here described, were often covered with 

 a metallic crust, which seems as if melted upon the vitreous 

 matter of the interior of the tube, and which comes from 

 the particles of metal detached by the action of the appa- 

 ratus of the conductor wires : thus when these extremities 

 were of gold or silver, the glass tubes became perfectly 

 gilded either with the one or the other metal. 



Chap. IT. 

 Theory of the Decomposition of Liquids ly means of Gal- 

 vanic Electricity. 



XV. The decomposition of water by the electrometer ap- 

 paratus has for a long time exercised the ingenuity of che- 

 mists and naturalists, to whom this phaenomenon affords a 

 delicate problem to resolve in order to reconcile it with the 

 theory of the nature of water. It is first necessary to know 



if 



