404 Progress in Science. [July, 
That such iron has really been decidedly altered in charaéer is evinced again 
by the fact that it refuses to reduce copper from solutions of its salts. It 
appears from Dr. Schonn’s observation, that if cadmium is wrapped with 
some platinum wire, it may be placed, without being in the least a¢ted upon, 
in strong nitric acid, though if the wire surrounding is removed, or if the 
acid is diluted, the cadmium is instantly attacked, thus showing that the 
passivity of the cadmium is due entirely to its contact with the platinum. 
The same author has shown that tin will give a similar phenomenon. 
M. D’Arlincourt has invented a relay said to be very easily adjusted and 
effective inits working. At the negative extremity, a, of a powerful horse-shoe 
magnet, c, are fixed the two poles of an eleCtro-magnet. A vertical bar of 
iron, P, centred at b in the positive pole of the horse-shoe permanent magnet, 
Fia. 3. 
and therefore permanently positively magnetised, vibrates between the two 
poles of the eleG&tro-magnet on the other extremity of the horse-shoe magnet. 
When a series of currents are passed through the wires of the electro-magnet, 
the bar Pp necessarily executes a corresponding series of vibratory movements, 
being displaced from the positive pole of the ele&tro-magnet, to which it 
returns on an interruption or change in the direction of the current. In this 
relay it is said that the difficulty of residual magnetism arising from the 
coercive force of the iron of the electro-magnet, is removed, and that the 
degree of rapidity of the oscillations of the bar consequently depends upon the 
rate at which the current can be made and interrupted in the line. With 
the relay disposed as a translating apparatus at Paris, messages were trans- 
mitted from Marseilles to London, traversing the cable at Dieppe. The trial 
showed the relay capable of being worked at a high speed and with great 
precision. 
M. Lenz has lately submitted a valuable paper on the properties of iron 
deposited by the eleGtric current. He arrives at the following conclusions :— 
That iron and copper deposited by the galvanic current retain a gas, princi- 
pally hydrogen. The volume of the gas absorbed by the iron varies between 
very wide limits, being sometimes as much as 185 times itsown volume. The 
absorption of the gas takes place principally in the first layers of metal 
deposited. The absorbed gas may be disengaged by heating the iron to a 
temperature of 100° C. These researches are likely to throw great light upon 
the electrolytic deposition of metals, and the obtaining of a reguline deposit. 
M. Volpicelli finds that the least flexure produced in a strip of metal gives 
rise to an electric current when the strip forms part of a condudtive circuit. 
This was shown for the first time by Peltier, and the results of his experiments 
were confirmed by M. A. dela Rive. Peltier formed a large circle with a 
copper wire, which he put in communication with a galvanometer of small 
resistance, and found that by bending the copper wire he produced a current 
in the galvanometer that could not be attributed to the magnetic influence of 
the earth. M. Volpicelli has repeated these experiments with a reflecting 
galvanometer, and has arrived at numerous new results. He finds that the 
electric current due to flexure may be obtained not only with iron, but with all 
metals; but that copper, under the same circumstances, produces on an 
astatic needle a greater deflexion than any other metal. These currents 
present the remarkable fact of an entire transformation of force into 
