CHAPTER VIII.
2.—FRICTION.
3.—CONDENSATION.
Q. What is meant by friction?
A. The act of rubbing two things together; as the Indians rub two pieces of wood together to produce fire.
Q. How do the Indians produce fire, by merely rubbing two pieces of dry wood together?
A. They take a piece of dry wood (sharpened to a point), which they rub quickly up and down a flat piece, till a groove is made; and the saw-dust (collected in this groove) soon catches fire.
Q. Why does the saw-dust of the wood catch fire by rubbing?
A. The latent heat of the wood is developed by friction; because the particles of the wood are squeezed closer together, and the heat pours out, as water from a sponge.
(The best woods for this purpose are box-wood against mulberry, or laurel against poplar or ivy.)