Fig. 47. SECONDARY BATTERY.
Battery, Secondary.
A voltaic battery whose positive and negative electrodes are formed or
deposited by a current from a separate source of electricity by
electrolysis. On disconnection the battery is ready to yield a current,
in the reverse direction of that of the charging current. The usual type
has lead plates on one of which lead binoxide and on the other of which
spongy lead is formed. The lead binoxide seems to be the negative
element, and it also acts as the depolarizer. The spongy lead is the
positive electrode. The solution is dilute sulphuric acid of specific
gravity 1.17. The action consists first in the oxidation of the spongy
lead. The hydrogen set free by the reaction, and which by electrolytic
transfer goes to the other plate, reduces the lead binoxide to
protoxide. The sulphuric acid then attacks the oxides and converts the
oxides into sulphates.
The charging process consists in sending a current in the reverse
direction through the battery. If there are several cells they are
arranged in series, so that each one receives the same intensity of
current. An electrolytic decomposition takes place, the lead sulphate on
one plate is reduced to metallic lead, and that on the other plate is
oxidized to lead binoxide. It is then ready for use.
71 STANDARD ELECTRICAL DICTIONARY.
The plates in a lead plate battery are of very large area per cell, and
are placed close together. Sometimes, as in Planté's battery, large flat
plates are laid together with a separating insulator between them, and
are then rolled into a spiral. Sometimes, the most usual arrangement,
the plates are in sets, the positive and negative ones alternating, and
each cell containing a number of plates.
To secure a good quantity of active material, the plates are sometimes
perforated, and the perforations are filled with oxide of lead. This
gives a good depth of material for the charging current to act on, and
avoids the necessity for a tedious "forming," q. v.
The electro-motive force of such a battery per cell is 2 volts. Its
resistance may only be one or two-hundredths of an ohm. An intense
current of many amperes can be supplied by it, but to avoid injuring the
cell a current far less than the maximum is taken from it.
To charge it, a slightly greater electro-motive force, the excess being
termed spurious voltage, is required.

Fig. 48. SIEMENS' AND HALSKE'S PAPER PULP BATTERY.
72 STANDARD ELECTRICAL DICTIONARY.
Battery, Secondary, Plante's.
Plante's secondary battery is one of the earlier forms of storage
battery, but has had much success. Two lead plates, large in area and
close together but not touching, are "formed," by exposure to an
electrolyzing current of electricity in one direction, while they are
immersed in dilute sulphuric acid. This converts the surface of one
plate into binoxide. The cell is then allowed to discharge itself almost
completely, when the charging current is again turned on. This process
is repeated over and over again, until the surfaces of the plates are
considerably attacked, one plate, however, being maintained in a state
of oxidation. After a few days of this operation a period of rest is
allowed between the reversals, which sets up a local action on the
oxidized plate, between the metallic lead of the plate, and its coating
of binoxide. This causes the lead to be attacked, under the influence of
the local couple, and sulphate of lead is formed, which, ultimately, by
the charging current is converted into peroxide. These operations
produce an exceedingly good battery. The process described is termed
forming.
The plates separated by strips of insulating material are generally
wound into a double spiral.
Battery, Siemens' and Halske's.
A Daniell battery of peculiar shape. The copper, C, is at the bottom of
the glass jar, A. The inner jar, K, has the form of a bell, and supports
a mass of paper pulp, which is dampened with sulphuric acid. The zinc,
Z, rests on top of the mass of pulp. The battery is very durable, but of
high resistance.
Battery, Sir William Thomson's.
A form of Daniell battery, of the gravity type. The receptacles are
shallow wooden trays lined with lead. A thin plate of copper rests on
the bottom. The zinc plate is of gridiron shape, and rests on wooden
blocks which support it in a horizontal position above the copper. One
tray is placed on top of the other, the upper tray resting on the
corners of the zinc plate which rise above the level of the top of the
flat vessel. Thus connection is assured without wires or binding posts.
It is charged like a gravity battery. The density of the zinc sulphate
solution should be between 1.10 and 1.30. The circuit must be kept
closed to prevent deposition of metallic copper on the zinc. The entire
disposition of the battery is designed to reduce resistance.
Battery, Skrivanow.
A pocket battery of the De la Rue type, with a solution of 75 parts
caustic potash in 100 parts of water as the excitant. The silver
chloride is contained in a parchment paper receptacle. Its
electro-motive force is 1.45 to 1.5 volts.
Battery, Smee's.
A single fluid combination, with zinc positive plate, and a plate of
silver, coated with platinum black, for the negative plate. The finely
divided platinum affords a surface from which the hydrogen bubbles
instantly detach themselves, thus preventing polarization. The liquid is
a mixture of one part sulphuric acid to seven parts of water. For the
negative plate silver-plated copper, coated with platinum black, is
used. Electromotive force, .47 volt.

Fig. 49. SMEE'S BATTERY.
73 STANDARD ELECTRICAL DICTIONARY.

Fig. 50. SPIRAL BATTERY, OR HARE'S DEFLAGRATOR.
Battery, Spiral.
A battery whose plates of thin zinc and copper are wound into a spiral
so as to be very close, but not touching. Dilute sulphuric acid is the
excitant. It is now practically obsolete.
Synonyms--Calorimeter--Hare's Deflagrator.
Battery, Split.
A battery of a number of voltaic cells, connected in series, with their
central portion grounded or connected to earth. This gives the ends of
opposite potentials from the earth, and of difference therefrom equal to
the product of one-half of the number of cells employed, multiplied by
their individual voltage.
Battery Solutions, Chromic Acid.
A number of formulae have been proposed for these solutions. (See
Electropoion Fluid--Kookogey's Solution--Poggendorff's Solution--
Trouvé's Solution--Delaurier's Solution--Chutaux's Solution--Dronier's
Salt--Tissandier's Solution.)
Battery, Trough.
A battery whose elements are contained in a trough, which is divided by
cross-partitions so as to represent cups. A favorite wood for the trough
is teak, which is divided by glass or slate partitions. Marine glue or
other form of cement is used to make the joints tight. For porous cup
divisions plates of porous porcelain or pottery are placed across,
alternating with the impervious slate partitions.
Battery, Trouvé's Blotting Paper.
A battery of the Daniell type in which the solutions are retained by
blotting paper. A considerable thickness of blotting paper lies between
the two plates. The upper half of the thickness of the blotting paper is
saturated with a solution of zinc sulphate, on which the zinc plate
rests.
The lower half of the paper is saturated with copper sulphate solution,
and this rests upon the copper plate.

Fig. 51. TROUVÉ'S BLOTTING PAPER BATTERY.
74 STANDARD ELECTRICAL DICTIONARY.
Battery, Tyer's.
A modification, as regards the positive element, of Smee's battery, q.
v. The bottom of the battery jar contains a quantity of mercury in which
pieces of zinc are thrown, and this constitutes the positive element.
A ball of zinc at the end of an insulated copper wire affords the
connection with the zinc and mercury. Its great advantage is that the
smallest scraps of zinc can be used in it, by being dropped into the
mercury. The negative plate is platinized silver; the exciting liquid,
dilute sulphuric acid.