The principles of inorganic chemistry / by Wilhelm Ostwald ; tr.with the author's sanction by Alexander Findlay.

Date:
1902
Catalogue details

Licence: In copyright

Credit: The principles of inorganic chemistry / by Wilhelm Ostwald ; tr.with the author's sanction by Alexander Findlay. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    101/826 (page 69)
    vt = (1 + at)v0, vhere vt is the volume at the temperature t, v0 that at the melting joint of ice, and a the hundredth part of the expansion between the nelting point of ice (0° C.) and the boiling point ot water (100 C.). u numbers, a = 0-00367 or 1/273. This formula gives the expansion starting from the temperature of nelting ice. To obtain the expansion between any two temperatures and t', the above formula is applied to both temperatures, and v0 iliminated from the two equations. There is obtained 1 + at 1 + at From this it is seen that the volume observed at temperature t is •educed to the volume at normal temperature, 0° C., by dividing it by die quantity 1 + at. * It must be specially emphasised that the quantity a is the hundredth part of the expansion of unit volume between the melting point of ice and the boiling point of water, and not, let us say, between my one temperature and another 100° O. higher. As can easily be seen, the value of a, the coefficient of expansion of gases, is dependent on die choice of the initial temperature. The Temperature Scale.—Since the expansion by heat has the same value for all gases, independently of their nature, the change of /olume of gases is used for temperature divisions. The temperature )f melting ice is called zero and that of water boiling under atmospheric oressure 100. This range of temperature is divided into a hundred jarts or degrees, which are proportional to the change of volume. To listinguish this graduation from others which are also used, it is called he centigrade or the Celsius scale, and is denoted by C. Let, then, the volume of a given quantity of oxygen or of another ?as contained in a tube, be denoted by 0° C. (Fig. 15), the volume at he boiling point of water will be defined by the spot marked 100° C., ,nd the volumes oe and os will be to one another as 1 : 1‘367. The ength es is divided into one hundred parts, and each of these parts denotes C. Such a tube, in which the gas is enclosed by means of an easy- ooving piston, and which is graduated in the manner just described, ould, evidently, be used as a thermometer or measurer of temperature. The Absolute Zero.—The temperatures, however, which are met nth, are not confined to the range between the melting point of ice nd the boiling point. Beyond the latter, we can, evidently, extend ■ur thermometers indefinitely, for there is no evidence of a limit for figher temperatures. Towards the other side, however, our thermometer is limited, for we an subtract only a definite number of degrees before reaching the ero point of volume. This number can be calculated as follows. If