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Page:Popular Science Monthly Volume 35.djvu/622

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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,

PSM V35 D622 Tin boat propelled by camphor.jpg
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.

PSM V35 D622 Camphor movement on top of mercury.jpg
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"