Name any elastic substance you know about that is in every way a substitute for rubber.
What has been the relation between rubber and good roads?
Describe the structure of a bicycle tire.
Why are tar, pitch, and turpentine called naval stores?—and what determines the locality in which they are made?
What is varnish, and for what purposes is it used?
FOR STUDY AND REFERENCE
Obtain specimens of crude rubber, vulcanized rubber, and hard rubber; note carefully the characteristics of each.
Burn a very small piece of cheap white rubber-tubing in an iron spoon or a fire-shovel; note the character of the residue.
Obtain specimens of gutta-percha, resin, pitch, turpentine, shellac, copal, dammar, and creosote for study and inspection.