Home › Chemical Receipts › Weather Prognostics (Much mercury into the tube)

Weather Prognostics (Much mercury into the tube)

much mercury into the tube as will make it stand to the length of 3 or 4 inches; and introduce a long wire of iron to stir it during the boiling.

Expose the mercury in the tube gradually to the heat of a chafing-dish of burning charcoal, or a well regulated gas flame; and when it begins to boil, stir it gently with the iron wire, to facilitate the disengagement of the bubbles of the air. When the first portion of the mercury has been sufficiently boiled, and all the air extricated, remove the tube from the chafing-dish and allow the whole to cool, taking care not to bring it into contact with any cold substance. Introduce an equal quantity of mercury, and treat it in the same manner, withdrawing the wire a little so that it may not reach below the upper part of the mercury already freed from air. The chafing-dish must also be placed immediately under the mercury which has been last poured in. Repeat the same process with each successive portion of mercury till the tube is filled, always applying the heat very cautiously; and be equally careful in allowing it to cool before a fresh portion of mercury is poured in. The Aneroid Barometer Consists of a brass-box partially exhausted of air with an elastic lid of corrugated brass. Changes of atmospheric pressure are indicated by the movements of the lid which are transmitted to an index hand.

It is light, portable, contains no liquid, and is more sensitive than the mercurial barometer.