AN INFALLIBLE BAROMETER.
With a few cents any boy can buy the chemicals required for this barometer, and obtain an instrument much more reliable than many of the cheaper grades for sale in the stores. Put two drams of pure nitrate of potash, and half a dram of chloride of ammonium reduced to a powder, into two ounces of pure alcohol, and place this mixture in a clear glass bottle, covering the top with a piece of rubber or thin kid pierced with small holes.
If the weather is to be fine, the solid matters remain at the bottom of the bottle, and the alcohol is as transparent as usual. If rain is to fall in a short time, some of the solid particles rise and fall in the alcohol, which becomes somewhat thick and troubled. When a storm, tempest, or even a squall is about to come on, all the solid matter rises from the bottom of the bottle and forms a crust on the surface of the alcohol which appears to be in a state of fermentation. These appearances take place twenty-four hours before the tempest ensues, and the point of the horizon from which it is to blow is indicated by the particles gathering most on the side of the tube opposite to that part whence the wind is to come. The longer the diameter of the bottle the better for this kind of barometer.
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