This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
Melt some tallow and, while it is hot, put in some scraps of rubber from old rubber shoes or boots. Be careful to select rubber that is free from cloth. Put in as much of the rubber as the tallow will absorb. Stir freely while it is melting, and keep it away from any flames. Allow it to cool and set away for future use. Take enough for immediate use and warm it sufficiently so that it may be applied with a brush. - Contributed by F. S. Cummings, Detroit, Mich.