Paraffine Wax.
A hydro-carbon composed principally of mixtures of the higher members of
the paraffine series C n H2 n + 2. It is made from cannel coal, coal
tar, or petroleum by distillation. It is an insulator. Its resistance at
46° C. (114.8° F.) per centimeter cube is 3.4E16 ohms, or about the
highest resistance known.
Its specific inductive capacity (for milky wax) is 2.47 (Schiller). For
clear wax it is given as follows by different authorities:
1.92 Ayrton.
1.96 Wüllner.
1.977 Gibson & Barclay.
2.32 Baltzmann.
It is extensively used in condensers and other electric apparatus as a
dielectric and insulator.
Paragrêles.
Protectors against hail; lightning rods used to guard fields against
hail; of little or no real utility.
Parallax.
The apparent change in position of an object when looked at from two
points of view. By looking at an object a few feet distant first with
one eye and then with the other, the shifting in apparent position is
seen.
In reading the position of an indicator or needle over a scale parallax
introduces an error unless the eye is held vertically over the needle.
By making the dial of looking- glass and holding the eye so that the
reflection of its pupil is bisected by the needle this verticality is
ensured.
Parallel.
(a) In the nomenclature of electric circuits two or more conductors
leading from one point to another, are said to be in parallel.
(b) When two or more conductors connect two main leads of comparatively
large size and low resistance they are said to be in parallel or in
multiple arc. This order is easiest pictured as the rungs of a ladder in
parallel connecting its two sides representing the main leads.
It may be used as a noun as "arranged in parallel," or as an adjective
as "a parallel circuit," the opposite of series, q. v.
Paramagnetic. adj.
Possessing paramagnetic properties; tending to occupy a position with
the longer axis parallel to the lines of force of a magnetic field;
having magnetism; attracted by a magnet.
"If a homogeneous isotropic substance is placed in a magnetic field it
becomes magnetized at every point in the direction of the magnetic
intensity at that point, and with an intensity of magnetization
proportional to the magnetic intensity. When the positive direction of
the induced magnetization is the same as that of the magnetic intensity
the substance is called Magnetic or Paramagnetic; when it is opposite,
the substance is called Diamagnetic." (Emtage.)
A paramagnetic substance has high permeability or multiplying power for
lines of force, hence in a magnetic field a bar of iron, etc., is in
unstable equilibrium unless its longer axis is parallel with the lines
of force in order to reduce as much as possible the reluctance of the
circuit.