The new chemistry / by Josiah P. Cooke, Jr.

  • Josiah P. Cooke
Date:
1876
Catalogue details

Licence: Public Domain Mark

Credit: The new chemistry / by Josiah P. Cooke, Jr. Source: Wellcome Collection.

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    seated The etlier will expand and fill the space with its vapor, and the globe will hold just as much ether-vapor as if neither of the other two were present; and so we might go on, as far as we know, mdefimtely. There is not here a chemical union between the sev- eral vapors, and we cannot in any sense regard the space as filled with a compound of the three. It con- tains all three at the same time, each acting as if it were the sole occupant of the space ; and that this is the real condition of things we have the most unques- tionable evidence. You know, for example, that a vapor or gas exerts a certain very considerable pressure against the walls of the containing vessel. Now, each of these vapors exerts its own pressure, and just the same pressure as if it occupied the space alone, so that the total pressui-e is exactly the sum of the three partial pressui-es. Evidently, then, no vapor completely fills the space which it occupies, although equally distributed through it; and we can give no satisfactory explanation of the phenomena of evaporation except on the assumption that each substance is an aggregate of particles, or units, which, by the action of heat, become widely separated from each other, leaving very large intermolecular spaces, within which the particles of an almost indefi- nite number of other vapors may find place. Pass now to another class of facts, illustrating the same point. The three liquids, water, alcohol, and ether, are ex- panded by heat like other forms of matter, but there is a striking circumstance connected with these phenom- ena, to which I wish to direct your observation. I have, therefore, filled three perfectly similar thermometer- bulb tubes, each with one of those liquids. The tubes are mounted in a glass cell standing before the con-
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