Chapter II: TECHNOLOGY AND CHEMISTRY.--The Constituent Parts of Leather. The

composition of different leathers exhibited at the Paris
Exhibition.--Amount of leather produced by different tonnages of 100
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.