APPENDIX B. 241 



plains than on the summit of the mountains, or in 

 those portions of the atmosphere distant from the 

 sun. 



NOTE C. We see no reason for admitting, a 

 prioriy the constancy of the specific heat of bodies 

 at different temperatures, that is, to admit that 

 equal quantities of heat will produce equal incre- 

 ments of temperature, when this body changes 

 neither its state nor its density; when, for example, 

 it is an elastic fluid enclosed in a fixed space. 

 Direct experiments on solid and liquid bodies have 

 proved that between zero and 100, equal incre- 

 ments in the quantities of heat would produce 

 nearly equal increments of temperature. But the 

 more recent experiments of MM. Dulong and 

 Petit (see Annales de Chimie et de Physique ,^ob- 

 ruary, March, and April, 1818) have shown that this 

 correspondence no longer continues at tempera- 

 tures much above 100, whether these temperatures 

 be measured on the mercury thermometer or on 

 the air thermometer. 



Not only do the specific heats not remain the 

 same at different temperatures, but, also, they do 

 not preserve the same ratios among themselves, so 

 that no thermometric scale could establish the con- 

 stancy of all the specific heats. It would have been 

 interesting to prove whether the same irregulari- 



