94. 



Article V. 



Memoir 071 Colours in general, and particularly on a new Chro- 

 matic Scale deduced from Metallochromy for Scientific and 

 Practical Purposes. By M. Leopold Nobili of Reggio. 



From the BibliofJieque Universelle des Sciences, SfC. vol. xliv. xlv. Geneva. 

 (1S30, vol. II. p. 337, vol. 111. p. 35, Aug. and Sept.) 



I DISCOVERED in 1826 anew 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 

 sucTi 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 ne- 

 gative 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 com- 

 municated 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 pro- 

 ductions 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 

 blendingsf. 



* Biblioth. Univ. vol. xxxiii. xxxiv, xxxv. xxxvi. (Old Series.) Annates de 

 CIdmie et de Physique, vol. xxxiv. and xxxv. 



f [A specimen of the productions of this beautiful art was presented by the 

 inventor to the Royal Society, in whose Library it may be seen. — Edit.] 



