EETZ'S CHRONOGRAPH.]

* * * * *

COPPER VOLTAMETER.

Dr. Hammerl, of the Vienna Academy of Sciences, has made some
experiments upon the disturbing influences on the correct indications
of a copper voltameter. He investigated the effects of the intensity
of the current, the distance apart of the plates, and their
preparation before weighing. The main conclusion which he arrives at
is this: That in order that the deposit should be proportional to the
intensity of the current, the latter ought not to exceed seven amperes
per square decimeter of area of the cathode.

* * * * *

Speaking of steel ropes as transmitters of power, Professor Osborne
Reynolds says these have a great advantage over shafts, for the stress
on the section will be uniform, the velocity will be uniform, and may
be at least ten to fifteen times as great as with shafts--say 100 ft.
per second; the rope is carried on friction pulleys, which may be at
distances 500 ft. or 600 ft. so that the coefficient of friction will
not be more than 0.015, instead of 0.04.

* * * * *

A NEW OXIDE OF COPPER BATTERY.

By MM. F. DE LALANDE and G. CHAPERON.

We have succeeded in forming a new battery with a single liquid and
with a solid depolarizing element by associating oxide of copper,
caustic potash, and zinc.

This battery possesses remarkable properties. Depolarizing electrodes
are easily formed of oxide of copper. It is enough to keep it in
contact with a plate or a cell of iron or copper constituting the
positive pole of the element.

Fig. 1 represents a very simple arrangement. At the bottom of a glass
jar, V, we place a box of sheet iron, A, containing oxide of copper,
B. To this box is attached a copper wire insulated from the zinc by a
piece of India rubber tube. The zinc is formed of a thick wire of this
metal coiled in the form of a flat spiral, D, and suspended from a
cover, E, which carries a terminal, F, connected with the zinc; an
India-rubber tube, G, covers the zinc at the place where it dips into
the liquid, to prevent its being eaten away at this level.

The jar is filled with a solution containing 30 or 40 per cent. of
potash. This arrangement is similar to that of a Callaud element, with
this difference--that the depolarizing element is solid and insoluble.

[Illustration: FIG. 1.]

To prevent the inconveniences of the manipu