pounds of hides.--Percentage of tannin absorbed under different
methods of tanning.--Amounts of gelatine and tannin in leather of
different tonnages, etc.

Progress in American Pottery.

Photographic Notes.--Mr. Waruerke's New Discovery.--Method of
converting negatives directly into positives.--Experiments of Capt.
Bing on the sensitiveness of coal oil--Bitumen plates.--Method of
topographic engraving. By Commandant DE LA NOE.--Succinate of Iron
Developer.--Method of making friable hydro-cellulose.

Photo-Tracings in Black and Color.

Dyeing Reds with Artificial Alizarin. By M. MAURICE PRUD'HOMME.

III. ELECTRICITY, PHYSICAL SCIENCE, ETC.--On Faure's Secondary Battery.

Physical Science in Our Common Schools.--An exceptionally strong
argument for the teaching of physical science by the experimental
method in elementary schools, with an outline of the method and the
results of such teaching.

On the Law of Avogadro and Ampere. By E. VOGEL.

IV. GEOGRAPHY, GEOLOGY, ETC.--Petroleum and Coal in Venezuela.

Geographical Society of the Pacific.

The Behring's Straits Currents.--Proofs of their existence.