circular vessel.

The current passes from, the battery, up the pillar, down the legs of
the U to the liquid, thence through the insulated wire back to the
battery.

[Illustration: Fig. 21.]

This is the usual form of apparatus, modified in size for the vertical
or horizontal lantern.

(_To be continued._)

* * * * *




POISONS.


"Poisons and poisoning" was the subject of a discourse a few days ago
at the Royal Institution. The lecturer, Professor Meymott Tidy, began
by directing attention to the derivation of the word "toxicology," the
science of poisons. The Greek word [Greek: toxon] signified primarily
that specially oriental weapon which we call a bow, but the word in
the earliest authors included in its meaning the arrow shot from the
bow. Dioscorides in the first century A.D. uses the word [Greek: to
toxikon] to signify the poison to smear arrows with. Thus, by giving
an enlarged sense to the word--for words ever strive to keep pace, if