+-----------+---------------+-----------+ | Temp. by |Mean dilatation| Temp. by | |copper rod | of platina |platina rod| | Therm. | in volume. | Therm. | +-----------+---------------+-----------+ | | | | | 100° | ¹/₃₇₇₀₀ | 100° | | 328.8 | ¹/₃₆₃₀₀ | 311.6 | +-----------+---------------+-----------+ Connected with this subject was another important enquiry, whether the capacities of bodies for heat remain constant at different temperatures, or whether they diminish or increase as the temperature advances. In other words, does a body that requires a certain quantity of heat to raise it from 0° to 100° centigrade, require the same quantity to raise it from 100° to 200°, and from 200 to 300°, &c.; or does it require less or more as we ascend? This enquiry involves that of the measure of temperature. They adopt the uniform expansion of air, or the air thermometer, as the proper measure, and find the capacity of iron, From 0° to 100° = .1098 0 to 200 = .1150 0 to 300 = .1218 0 to 350 = .1255 the capacity of an equal weight of water being 1. The following Table exhibits the capacities of seven other bodies according to their results. TABLE V. +---------+--------------+--------------+ | |Mean capacity |Mean capacity | | | between 0° | between 0° | | | and 100° | and 300° | +---------+--------------+--------------+ |Mercury | .0330 | .0350 | |Zinc | .0927 | .1015 | |Antimony | .0507 | .0549 | |Silver | .0557 | .0611 | |Copper | .0949 | .1013 | |Platina | .0335 | .0355 | |Glass | .1770 | .1900 | +---------+--------------+--------------+ According to this table the capacities of bodies _increase_ with the temperature in a small degree: and the increase, though it would still exist, would be less, if the common mercurial thermometer were the measure of temperature. Also supposing that thermometers made of these bodies and graduated by immersion in freezing and boiling water into 100°; if these were all immersed in a fluid in which an air thermometer stood at 300°. Then the relative temperatures of the several thermometers would be as under, if measured by the absolute quantity of heat acquired, namely, Iron 322.2° Silver 329.3 Zinc 328.5 Antimony 324.8 Glass 322.1 Copper 320.0 Mercury 318.2 Platina 317.9 From these observations they infer that the law which has been promulgated for the refrigeration of bodies, cannot be strictly true: namely, that bodies part with heat in proportion as their temperature exceeds that of the surrounding medium.