Reservoir, Common.
A term applied to the earth, because all electrified bodies discharge
into it if connected thereto.
Fig. 289. DIAGRAM OF THOMSON'S REPLENISHER.
Residual Atmosphere.
The air left in a receiver after exhaustion by an air pump. The
quantity, where good air pumps are used, is very minute.
Residue, Electric.
The residual charge of a condenser. (See Charge, Residual.)
Resin.
(a) The product obtained by non-destructive distillation of the juice of
the pitch pine. It is the solid residue left after the turpentine has
been evaporated or distilled. It is a mixture of abietic acid C44 H64 O5
and pinic acid C20 H30 O2. It is an insulator; its specific inductive
capacity is 2.55. (Baltzmann.)
Synonyms--Colophony--Rosin.
(b) The name is also generally applied to similar substances obtained
from the sap of other trees; thus shellac is a resin. The resins are a
family of vegetable products; the solid portions of the sap of certain
trees. Common resin, lac, dragons blood, are examples. They are all
dielectrics and sources of resinous or negative electricity when rubbed
with cotton, flannel, or silk. (See Electrostatic Series.)