consequently increased retention of carbonic acid gas. If the keg or
barrel is filled with beer, the same becomes apparent from the beer
showing itself in the glass gauge; then the faucet, B, is closed, the
copper bung is lifted out of the bung hole, and the beer contained in
the pipe is just sufficient to completely fill the keg, which is then
bunged up, while the apparatus is transferred to the next keg. Should
the attendant carelessly neglect to close the faucet in proper time, the
surplus beer will not necessarily be wasted, but will be collected in
the vessel, D, whence it can be drawn off through e.--_Chemical Review_.

[Illustration]

* * * * *




ON THE DIFFERENT MODIFICATIONS OF SILVER BROMIDE AND SILVER CHLORIDE.


Hermann W. Vogel has made a comparative study of the properties of
silver bromide, obtained by precipitation in an aqueous solution of
gelatin, and those of the same compound prepared by precipitation in an
alcoholic solution of collodion. In 1874 Stas called attention to six
modifications of silver bromide. One of these, granular bromide of
silver, obtained by boiling the flocculent precipitate for several days
with water, he stated, was the most sensitive to light of all substances
known; exposure for two or three seconds to the pale blue flame of a
Bunsen burner being sufficient to blacken it. Important as this fact was
for photographers it was not applied for years, and it was only in