Introduction to the study of inorganic chemistry / by William Allen Miller.

  • Miller, William Allen, 1817-1870.
Date:
1871
Catalogue details

Licence: Public Domain Mark

Credit: Introduction to the study of inorganic chemistry / by William Allen Miller. Source: Wellcome Collection.

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    for if the pressure upon tlie gas be by any otlier suitable means lessened to one-half, the air will immediately become doubled in bulk. If, on the other hand, the pressure be doubled, the air will become reduced in bulk to one-half. Gases, in fact, occupy a space inversely as the pressure to which they are subjected ; and, in order to avoid inaccuracy in measuring them, they are always compared by calculating them as if subjected to a fi.\ed or standard pressure of a column of mercury at 0° C. of 760 mm. high. Suppose V to be the observed volume (after it has been corrected, if necessary, for temperature),/ the pressure at the time of observation, measured by the height of the mer- curial column in the barometer in millimetres, and Fth.e volume corrected to the pressure of 760 mm. of mercury, then— 760 In taking the specific gravity of gases, it has been the practice to compare them with an equal bulk of dry air as the standard. IMien, for instance, it is said that the specific gravity of oxygen is 1-10563, the expression means that if a vessel which holds a certain volume of dry air which weighs exactly i gram, were filled with dry o.xygen gas, at the same temperature and ])ressure, the weight of this oxygen would be 1-10563 gram; the same bulk of drj^ hydrogen would be only -0691 gram, and the specific gravity of hydrogen is said to be -0691. This ])ractice of comparing gases with air is both cus- tomary and convenient; but it has been objected to on the ground that air is a mixture, and not a true chemical com- pound. Now the proportions of the substances in a mixture are liable to variation, while those of a chemical compound are invariable. Fortunately for the accuracy of the data founded on comparison with the air as a standard, the ]n-o- portions of the oxygen and nitrogen in the air do not vary practically to any important amount, but the objection in