Burlington weekly free press. [volume] (Burlington, Vt.) 1866-1928, 1916-08-10

solution is then slowly added to alcohol.
During the mixing process the vApors
given off are dangerous. because Of their
high degree Of inflammabiity When
dry the illuminate must be handled with
the greatest care. for II explodes with
great force when struck or Jared This
substance is widely used m set of
charges 81 dynamite euhpo wder and
nitro glycerine.
IN ELECTRICAL APPARATUS
In the electrical trades mercury is used
principally in mercury arc rectifers and
mercury vapor lamps. The mercury arc
rectifier Is an ingenious device FOR con-
verting alternating into direct current.
II consists OF a glass bulb containing
mercury and mercury vapor and operate.
on the principle OF a ratchet. permitting
the alternating current to flow in ono
direction but offering high resistance TO
its passaee in the opposite direction.
Thus the current is changed from alter.
nate waves flowing back and forth into
pulsating waves flowing in the same
direction. The operation Of the rectifier
depends upon the peculiar behavior ct
electricity in vacuum tube containing
mercury vapor. The current will readily
flow from solid electrode in such
tube TO the mercury vnpor, but when the
current attempts to flow back from the
vapor to the solid electrode the resistance
presented to IT'S passage is too great. This
resistance to its passage in one direc-
ton only thus acts like a check valve,
and with each change in the direction
OF the current flow. a part OF the cur
rent is retained and converted into con-
tinuous current which passes out through
the mercury electrode.
The mercury vapor lamp Is tube and
bulb with an operating mechanism at
tached The tube contains quantity Of
mercury but practically no air and has
an electrode at each end, Electricity
passing through the tube and its cleo
. trodes changes part Of the mercury into
vapor. The vapor. unlike most vapor, has
the peculiar property OF becoming uh,in-
Gus when a sufficient quantity Of electric
current lie passed through i: in a vacuum.
! The light produced 10 of penetrating
greenish tint and is used in places where
| It Is desired TO illuminate a large area
at slight expense, and where tho color
| Of the light is not obiectiona bile. This
government printing office in Washing
]
yards and machine shops are extensive
users of the murcury vapor lamp. ow
ing to the actinic power of the light they
are often used in motion picture and pho
| tographic studios. This IL the only form
of electric light which is more economical
than the incandescent house lamp The
color of the light, however. makes II
| undesirable as a house illuminan:
SEPARATES GOLD.
Mercury has a great affinity for gold.
! A small quantity Of mercury dropped on
sold ring cannot be removed without
the greatest difficulty. It is this property
which has made 1t valuable in the metal
lurgical processes for the extraction OF
gold from It's ores. The powdered quartz
is mixed with mercury and the GOLD and
the mercury unite to form an amalgam.
/ The amalgam is placed IN a vessel and
heated The mercury is distilled off IN
the form Of vapor ana the gold is LETT
in a pure state. Silver is Also extracted
in a similar manner.
fair idea of the Importance OF NOR
curry in the electrical field may he OBJ
tanned from the appended list which
gives only a few of the purposes for
which mercury is used in the operation
and manufacture Of things electrical:
! Wireless instruments, electric batteries,
flow meters vacuum pumps,electric'
plating, switches, mercury vapor lamps
mazda lamps, rectifers, x-ray apparatus,
! Coolidge tubes, electric interrupter. ba'
rometers.