redness in the platinum capsule until the weight becomes constant. The
results are too high.

_Selenium and Tellurium._--Both these bodies are readily and
completely reduced by the current either in acid or alkaline
solutions. Selenium is thrown down at first of a fine brownish red,
which gradually becomes darker. The deposit of tellurium is of a
bluish black color. If the current is feeble, the deposit of selenium
is moderately compact; that of tellurium is always loose, and it often
floats on the liquid. A strong current precipitates both as powders.
The positive pole is coated during electrolysis with a film of a dark
color in case of selenium, but of a lemon yellow with tellurium. As in
case of arsenic and antimony, the hydrogen evolved at the negative
pole combines with the reduced substances, forming hydrogen, selenide,
or telluride, which remain in part in solution in the liquid. The
reduced metal separates out at the anode in a friable
condition.--_Zeitschrift fur Analytische Chemie, and Chemical News._

* * * * *

THE ELECTRO-CHEMICAL EQUIVALENT OF SILVER.

A very careful and important determination of the electrochemical
equivalent of silver has been made at the observatory of the Physical
Institute of Wuerzbourg, and the results are that an ampere current
flowing for a second, or a coulomb of electricity deposits 1.1183
milligrammes of silver or 0.3281 milligramme of copper, and decomposes
0.09328 milligramme of water, a result agreeing closely with that of
Lord Rayleigh recently communicated to the Physical Society. An ampere
therefore deposits 4.0259 grammes of silver per hour; Kohlrausch's
value is 4.0824, a value hitherto accepted universally. This value is
so useful in measuring electric currents with accuracy, and free from
the disturbances of magnetism, etc., that it is eminently satisfactory
to find the German value agree with that of Lord Rayleigh, which will
probably be adopted by English electricians.

* * * * *

A NEW STANDARD LIGHT.

Herr Hefner-Alteneck has suggested a new standard light for
photometric purposes, which promises to be very simple and effective
in operation. The light is produced by an open flame of amyl-acetate
burning from a wick of cotton fiber which fills a tube of German
silver 1 in. long and 316 mils. internal diameter; the external
diameter being 324 mils. The flame is 1.58 in. high fro