266 Correspondence of J. Nickles. 
But this is not so in the experiment, and because the currents do 
not pass along the wires as MM. de la Provostaye and Desains regard 
it. the aid of the platinum wire the two circuits of the pile form 
no more than one, whose tension varies with the direction of the cur- 
rents. When both are propagated in the same direction, a¢, 
On the contrary, when the currents pass in opposite directions, 
the batteries A and B are coupled for tension, a condition less favorable 
form of these phenomena. 
[take an electromagnet which I place in a circuit, formed of four of 
Bunsen’s pairs. The electromagnet carries 200 kilograms. If now I 
interpose four other elements in an opposite direction, | ought to have 0, 
according to both theories; in fact the magnetization disappears en- 
tirely. But if in place of four reversed elements I take only éwo, I find 
that the electromagnet retains part of its force ; and, provided the mode 
communication of the conductors remains the same in both cases, 
thi 
derived currents, and the magnet was in a certain degree magnetised. 
Various Memoirs.—Among the memoirs brought before the Acad- 
moirs by M. Virchow, relating to the discovery in the human body fr 
t 
t by 
dia-rubber, etc.—A memoir of M. Schlosing, on testing for nitri¢ aci 
accompanied by organic matters. The author who is inspector of to- 
bacco, has applied his process to this vegetable substance. 
