s of the grid. A sufficient amount of
sulphate is left in the plates to bind together the active material.
Without this sulphate the positive paste would simply be a powder and
when dry would fall out of the grids like dry dust. Fig. 7 shows a
formed plate ready to be burned to the strap.

Separators

In batteries used both for starting and for lighting, separators made
of specially treated wood are largely used. See Fig. 8. The Willard
Company has adopted an insulator made of a rubber fabric pierced by
thousands of cotton threads, each thread being as long as the
separator is thick. The electrolyte is carried through these threads
from one side of the separator to the other by capillary action, the
great number of these threads insuring the rapid diffusion of
electrolyte which is necessary in batteries which are subjected to the
heavy discharge current required in starting.

In batteries used for lighting or ignition, sheets of rubber in which
numerous holes have been drilled are also used, these holes permitting
diffusion to take place rapidly enough to perform the required service
satisfactorily, since the currents involved are much smaller than in
starting motor service.

[Fig. 8]

Fig 8. A Pile of Prepared Wooden Seperators Ready to be Put Between
the Positive and Negative Plates to Form the Complete Element.

For the wooden separators, porous wood, such as Port Orford cedar,
basswood, cypress, or cedar is used. Other woods such as redwood and
cherry are also used. The question is often asked "which wood makes
the best separators?" This is difficult to answer because the method
of treating the wood is just as important as is the kind of wood. The
wood for the separators is cut into strips of the correct thickness.
These strips are passed through a grooving machine which cuts the
grooves in one side, leaving the other side smooth. The strips are
next sawed to the correct size, and are then boiled in a warm alkaline
solution for about 24 hours to neutralize any organic acid, such as
acetic acid, which the wood naturally contains. Such acids would cause
unsatisfactory battery action and damage to the battery.

The Vesta separator, or "impregnated mat," is treated in a bath of
Barium salts which form compounds with the wood and which are said to
make the separators strong and acid-resisting.

[Fig. 9 Philco slotted retainer]

Some batteries use a double separator, one of which is the wooden
separa