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THE POPULAR SCIENCE MONTHLY.
destroyed or diminished, while that forward continues in full force to draw the boat onward. If a bit of camphor be substituted for the alcohol, its vapor has the same effect upon the tension,
Fig. 6.—Tin Boat sailing around on Water by the Aid of a Bit of Camphor.
and the boat may be made to sail regularly, with considerable speed, for hours. The experiment is made more spectacular by furnishing the boat with a mast carrying a flag.
Fig. 7.—Movements of Fine Grains of Camphor on the Surface of Mercury.
In another experiment described by M. Devaux, a few granules of camphor are sprinkled upon mercury, and breathed upon till a kind of lye is formed, when a multitude of long-tailed "tadpoles"
