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barometer, chemical

"Three Men in a Boat" refers to "the new style of barometers, the long straight ones" with pointers for yesterday and today and instructions for correcting to sea-level. Ours also includes a chemical barometer.
B/001

2317. Chemical Barometer

Take a long narrow bottle, such as an old-fashioned Eau-de-Cologne bottle, and put into it two and a half drachms of camphor and eleven drachms of spirit of wine; when the camphor is dissolved, which it will readily do by slight agitation, add the following mixture:
Take water, nine drachms; nitrate of potash (saltpetre), thirty-eight grains; and muriate of ammonia (sal ammoniac), thirty-eight grains.
Dissolve these salts in the water prior to mixing with the camphorated spirit; then shake the whole well together. Cork the bottle well, and wax the top, but afterwards make a very small aperture in the cork with a red-hot needle.

The bottle may then be hung up, or placed in any stationary position. By observing the different appearances which the materials assume, as the weather changes, it becomes an excellent prognosticator of a coming storm or of fine weather.

In fine weather the solid part will collect at the bottom and the liquid be quite clear; at the approach of rain the solid matter will gradually rise, and small crystalline stars will float about. Wind is indicated by flakes of the compositional in the form of leaves or feathers, appearing on the surface, and the whole seeming thick and in a state of fermentation. The quarter from which the wind blows is shown by the particles lying more closely to the glass on the opposite side from which the tempest is coming.