Elements of chemistry, including the recent discoveries and doctrines of the science / by Edward Turner.

  • Turner, Edward, 1798-1837.
Date:
1833
Catalogue details

Licence: Public Domain Mark

Credit: Elements of chemistry, including the recent discoveries and doctrines of the science / by Edward Turner. Source: Wellcome Collection.

    84/1026 (page 56)
    pound of water at 172°, the temperature of the mixture will be intermediate between them, or 102°. But if a pound of water at 172° be added to a pound of ice at 32°, the ice will quickly dissolve, and on placing a thermometer in the mix- ture, it will be found to stand, not at 102°, but at B20 io, In this experiment, the pound of hot water, which was originally at 172°, actually loses 140 degrees of caloric, all of which entered into the ice, and caused its liquefaction, but did not affect its temperature ; and it follows, therefore, that a quan- tity of caloric becomes insensible during the melting of ice, sufficient to raise the temperature of an equal weight of water by 140 degrees of Fahrenheit. This explains the well known fact, on which the graduation of the thermometer depends,—that the temperature of melting ice or snow never exceeds 32° F. All the caloric which is added becomes in- sensible, till the liquefaction is complete. The loss of sensible caloric which attends liquefaction seems essentially necessary to the change, and for that reason is frequently called the caloric of fluidity. The actual quan- tity of caloric required for this purpose varies with the sub- stance, as is proved by the following results obtained by Irvine. The degrees indicate the extent to which an equal weight of each material may be heated by the caloric of fluidity which is proper to it, Caloric of Fluidity. Sulphur. : : ? 143°.68 F. Spermaceti 145° F. Lead } . 162° Bees-wax : 175° ‘Zinc f : 493° Tin : ; 500° Bismuth 4 : : ; 550° As so much heat disappears during liquefaction, it follows that caloric must be evolved when a liquid passes into a solid. This may easily be proved. The temperature of water in the act of freezing never falls below 32° F. though it be ex- posed to an atmosphere in which the thermometer is at zero. In order that the water under such circumstances should preserve its temperature, it is necessary that heat should be supplied as fast as it is abstracted ; and it is obvious that