TRANSACTIONS OF THE SECTIONS. 31 
On Unilateral Conductivity. By Arraur Scuustrr, Ph.D. 
While engaged in other work the author discovered a new phenomenon in elec- 
tricity which may conveniently be called unilateral conductivity. His experiments 
show thatin a circuit composed entirely of copper wires, joined together by means of 
binding-screws, the electric conductivity in one direction may be different from what 
it is in the opposite direction. Ifa coil of wires be connected with the galvanometer, 
and a magnet rotates rapidly within, the coil-currents in alternate direction will pass 
through the galvanometer. Their effect, however, on the needle will counteract each 
other, and the needle will sliow no permanent deflection if the currents are equally 
strong. On the other hand, if the needle shows a permanent deflection, one current 
must be stronger than the other; and this again can only be caused by a difference 
in the conductivity, as the electromotive force acting in opposite directions must be 
equal. It isfound that sometimes the currents induced by the rotating magnet haye 
a very strong effect on the needle, and the effect shows best in wires which have not 
been used for a certain time. The most remarkable fact connected with unilateral 
conductivity is, that a circuit of wires not showing unilateral conductivity may be 
made to conduct unilaterally by merely introducing for a short time a wire which 
shows the effect. When the wire is taken out, the original circuit will again show 
unilateral conductivity. The air condensed on the surface of the wire may possibly 
cause the phenomenon. Two wires screwed together may not touch each other, 
but a small layer of air may separate them, A voltaic arc, the two electrodes of 
which are of different form, will, as is known, show what is called unilateral conduc- 
tivity, and a copper wire separated from the binding-screw by a thin layer of air 
will act somewhat like a voltaic arc. In order to test the theory according to which 
the facts mentioned above are easily explained, air was artificially condensed on the 
wire by having its ends put for a certain time into powdered charcoal. A wire 
which showed no unilateral conductivity was thus made to show it; and after it had 
been destroyed again, which generally can be done by rubbing the wire or screwing 
it to another binding-screw, unilateral conductivity was produced a second time by 
the same means. A third attempt, however, failed, and from that time all the 
means by which usually unilateral conductivity had been produced were not suc- 
cessful, If, therefore, the above theory is the correct explanation of unilateral con- 
ductivity, some unknown secondary cause (perhaps the diffusion of the gas into the 
wire) must be active, which at certain times prevents it being produced, 
A New Method of constructing Carbon-cells and Plates for Galvame Battertes, 
By W. Symons, F.0.8. 
The author mixes finely powdered wood-charcoal with a syrup of white sugar to 
a proper consistence, In this thick syrup he dips paper moulds, only covering the 
outside. After drying he redips, and repeats until sufficiently thick. When well 
dried, the cells are packed in sand and baked in an oven sufficiently hot to burn out 
the paper moulds. Then soaked in weak hydrochloric acid, dried, soaked in sugar- 
syrup, then buried in sand and gradually brought up to a white heat. The carbon 
has a good metallic ring and a brilliant fracture. The outside of the cells can be 
covered with paper and dipped in melted paraffin, Rods and plates of carbon can 
be easily rolled out or pressed if made of a similar mixture, but thicker. 
Notes on a New Method for the Electrochemical Decomposition of Oils and 
other Non-conducting Liquids*. By W. Symons, £.C.S. 
The author described a method for subjecting various oils, carbon disulphide, and 
other non-conducting liquids to the action of a weak but continuous galyanic current, 
by dissolving them either in a solution of zine chloride in alcohol or of ferric chloride 
in ether. The latter he finds the best medium ; and oils &c. dissolved in it may be 
subjected to the galvanic current for some days, various products of decomposition 
* The paper is printed in full in the ‘ Pharmaceutical Journal’ for October 1874. 
