160 Intelligence and Miscellaneous Articles. 



pressing the finger against any portion of the plate put in vibration 

 by a bow. As the mechanical pressure on the vibrating plates pro- 

 duces symmetrically nodal lines corresponding to the point of pres- 

 sure, I thought that metal plates immersed in voltaic baths might 

 have a certain inertia at the points at which they were pressed. 

 Facts have answered my anticipations ; metallic plates struck by elec- 

 tricity, though apparently motionless, emit notes which we do not hear, 

 but which may produce designs on the surface under given conditions. 



The following is the manner in which I have made the experiment. 

 In a solution of acetate of iron to which a few grammes of phos- 

 phoric acid and some fragments of phosphorus were added, I im- 

 mersed two plates of ordinary iron — one in connexion with the posi- 

 tive, and the other with the negative pole of a Bunsen's battery of 

 three elements. Between these two plates and at right angles to 

 their surface I fixed a glass plate 210 millims. in length and 35 mil- 

 lims. square, in such a manner that it pressed with its edge against 

 the two iron plates suspended by wires to the contrary poles. I 

 may add that, in order to produce a better contact between the two 

 plates of iron and the glass plate, I fitted pieces of wood between the 

 sides of the trough and the external surfaces of the two plates, to 

 keep them constantly pressed against the glass plate. After two 

 days of voltaic action, metallic iron was deposited on the plate sus- 

 pended to the negative pole in vertical bands parallel to the two 

 sides of the edge of the glass plate, a ridge alternating with a fur- 

 row. The hollows corresponded to the space occupied by the edge 

 of the glass plate, and the reliefs to the sides of the same plate. 

 The hollow lines (those, that is to say, in which no metallic iron was 

 deposited) were therefore nodal lines, and the lines on which the iron 

 was deposited were lines of vibration or segments. They might have 

 been the strings of a harp manufactured in the mysterious silence 

 of the molecular recesses. 



Instead of a straight glass I substituted an S-shaped one, so that 

 the line formed by the contact of the glass upon the iron was curved. 

 I thus obtained a curvilinear deposit of iron with alternate raised 

 and depressed curved lines. But the curved lines were neither so sharp 

 nor so well defined as the straight ones, because the terminal section 

 of the badly curved plate was not ail in one plane, and a consider- 

 able part was not in contact with the iron plate. The current, more- 

 over, was weakened and the bath a little exhausted, which must have 

 had some influence on the want of sharpness of the nodal and the 

 vibrating lines. 



The uniform pressure of a glass plate has been sufficient to render 

 inert' entire spaces of iron, so as to prevent any deposition on 

 them. If this is the case with right and with curved lines, it cannot 

 be doubted that, by making designs in glass (and perhaps in clay 

 or porcelain), all the parts in contact with the edge of the design 

 would be preserved from metallic deposits. It is probable that the 

 same design would be reproduced on the same surface a greater 

 number of times, according as the space left free by the pressing sur- 

 faces were more extended.— Comptcs Rendus, October 7, 1867. 



