dy hot part of the compound
upward throughout the whole mass-so that before the top part of it is
brought to a molten condition the lower inside layers are very hot
indeed. If there is too much in the kettle these lower layers are
necessarily raised in temperature beyond the point where they lose
some of their volatile oils-they are "burned" before the whole mass of
compound can be brought to a molten state.

Do not use too large a heating flame under the kettle for the same
reasons. A flame turned on "full blast" will certainly "burn" the
bottom layers before the succeeding layers above are brought to the
fusion point. USE A SLOW FLAME and TAKE TIME IN MELTING UP THE
COMPOUND. It PAYS in the resulting jobs.

The more compound is heated, the thinner it becomes--it should never be
allowed to become so hot that it flows too freely--it should never
exceed the viscosity of medium molasses. It should flow freely enough
to run in all narrow spaces but NOT freely enough to flow THROUGH them
before it cools.

Stir the kettle frequently during the day. It is advisable about once
a week to work as much compound out of the kettle as possible, empty
that still remaining, clean the kettle out, and start with fresh
compound.

NEVER USE OLD COMPOUND OVER AGAIN--that is, do not throw compound
that has been dug out of used batteries into the kettle with the new
compound. The old compound is no doubt acid soaked, and this acid will
work through the whole molten mass, making a satisfactory job a very
doubtful matter indeed.

Cold weather hardens sealing compound, of course, and renders it
somewhat brittle and liable to crack. This tendency could be overcome
by using a softer compound, but, on the other hand, compound so soft
that it would have no tendency to crack in cold weather would be so
soft in warm weather that it would fail to hold the assembly with the
necessary firmness and security. It is far better policy to run the
risk of developing a few cracks in the winter than a loose assembly in
summer. Surface cracks developed in cold weather may be easily
remedied by stripping off the compound around the crack with a heated
tool, flashing with the torch and quickly re-sealing according to the
above directions.

It is not practical to work any oil agent, such as paraffin or castor
oil, into the compound in an effort to soften it for use in cold
weather.

SHELVING AND RACKS

The essential things about shelving in a batter