Page:Scientific Memoirs, Vol. 1 (1837).djvu/106



DISCOVERED in 1826 a new class of facts and gave them the name of electro-chemical appearances. The following is one of the principal experiments connected with those facts.

A plate of platina is laid horizontally at the bottom of a vessel made of glass or china. A platina point is vertically suspended over this in such a manner that the distance between the point and the plate may be about half a line. A solution of acetate of lead is next poured into the vessel so as not only to cover the plate, but to rise two or three lines higher than the point. The plate and the point are now brought into communication, the former with the positive and the latter with the negative pole of an electric pile. At the moment when the voltaic circuit is closed, a series of rings similar to those formed at the centre of the Newtonian lenses is to be seen on the surface of the plate precisely under the point. This fact, which could not fail to strike any one observing it for the first time, led me to the discovery of others, which I have communicated to the public in four successive Memoirs. I foresaw from the very first the advantages that the arts were likely to derive from this new method of colouring metals; but it was not until toward the close of 1827 that I began to attend seriously to its application. My first attempts I forbear to mention, being more desirous to call attention to the productions which I obtained in the course of 1828, and in the November of that year presented to the French Institute. These productions consisted of several plates of coloured metal, and excited the particular attention of that illustrious body by the beauty and vividness of their tints, the precision of their outlines, and the softness of their blendings.