Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1916-11-18

| converted into electrical energy IN n
I given time, Just as the rate at wlNea
| coal is consumed in the fire under 4
boiler depends upon how much heat
energy must be transformed into me-
| chanical energy and delivered by the
engine. II the cell supplies one am
/ nere FOR one hour there is definite
| GilaItlty Of zinc consumed, aud Ii il
supplies two ampereS for one hour
there is just twice the quantity or zinc
| consumed IL current OF electricity
be sent through cell in the opposite
direction to that in which it tends 20
! flow due TO the pressure of the cell
.tself, there will be reversed chemi-
cal action taking place i'm the cell. and
the same amount Of zinc will be re-
covered from the electrolyte and De.
( posted upon the zine plate in one
/ hour by a given current as was con.
sumed in supplying the same value
! OF current for one hour. The rate 1T
which the zine may be recovered from.
| the electrolyte and deposited on the
! zinc plate will be twice as great for
a current of two ampereS as for 4
current of one ampere; three times as
4 great for q current of three amperes
/ as for a current of one ampere, etc
! This last operation of breaking IN the
electrolyte and depositing the metal
| contained in the electrolyte is called
| electrolysis. This is the principle
| used in electroplating
The quantity of any metal forming
the negative plate of a cell which IS
] consumed in one hour, when the cell
is supplying current Of one ampere.
or which is deposited in one hour
! when a current of one ampere is
caused to flow backward through the
cell, is called the electrochemical
equivalent of the Substance.
| Damage Due to Electrolysis
Under certain conditions consider
able damage may occur to some part
| OF an electrical circuit due to electro
lysis For example, if two pieces of
metal which form a part of an cleo
trical circuit are making poor contact
with each other and this contact is
moist, there will be a chemical action
taking place at the contact when
there is a current in the circuit which
results in the metal from which the
/ electricity flows being wasted away
and carried across the contact and de-
posted on the other piece of metal.
The positive and negative terminals
of a direct current surface can be de-
termined by dipping the terminals, at
some distance apart, into tumbler Of
water. The current in passing
| through the water deeomposes it into
oxygen and hydrogen, the oxygen go
ing in the opposite direction to the
current and the hydrogen in the same
direction as the current. The volume
of the hydrogen gas resulting from the
decomposition of the water will be APP
proximately twice as great as the
volume of the oxygen gas, and hence
there will be more bubbles collected
/ on the negative terminal than on the
| positive terminal as shown in Fig.
ure g.
The Leclanche cell is a good ex-
ample OF an open type of wet cell.
and it's operation will be given some
what in detail, as the operation of
the dry cell described in the next
section is practically the same. The
| frs: forms of this cell consisted of a
carbon rod imbedded in mixture Of
manganese peroxide and broken car
bon, all contained in a porous cup.
This cup was placed in an electrolyte
of ammonium chloride, commonly call
ed sal ammoniac, and the negative
! terminal was formed from piece
! OF sheet Zinc, put into a cylindrical
form and surrounding the porous cup.
The construction OF the cell is shown
in Figure 4. The manganese peroxide
forms the depolarizer, and the only
object OF the porous cup was to hold
/ the mixture of manganese peroxide
and broken carbon around the positive
plate.
In the more modern forms of this
/ cell the porous cup has been dispens-
| ed with and mixture of carbon and
| manganese peroxide are moulded to
gether with a suitable binder.
Dry Cells
The modern dry cell, so extensively
used at the present time, may be
looked upon as slight modification
of the Leclanche cell. The chief diff
ference between them is that only
enough water is added TO the material
forming the electrolyte to moisten it
and an absorbent layer of starch paste,
plotting paper or cloth, which separ-
ates the positive and negative poles
of the cell. The negatives pole is a
hollow zinc cylinder closed at one
end, which also serves as eontainer
for the remainder of the cell. The
absorbent layer used to separate the
positive and negative poles is satur-
ated with a solution of sal ammoniac
and zinc chloride and placed next to
the zinc on the inside of the cylinder
The remaining space between the abb
! sorbent layer and the carbon rod is
filled almost to the top with moist
mixture composed chiefly OF manga
nese peroxide and graduated carbon.
! The manganese peroxide acts as the
depolarizer The remaining space at
the top Of the cup is usually filed
with a pitch composition which seals
the cell Terminals are provided at
the upper end OF the piece Of carbon
and also at the upper edge Of the
zinc cup. A vertical cross section of
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