262 Prof. Wartraann on the Cooling of Electrified Bodies. 



cover pierced at its centre with an opening destined to receive 

 the thermometer. Five of these apparatus were filled with 

 boiling water and submitted to examination. Here is a re- 

 sult, as an example, for 15° of cooling: — 



Mean time of cooling 1° C. of the 

 Nature of Inter. Exter. Electrified Non-elect, 



the Wood. Barom. Temp. humid. Surface. Surface. 



Oak . m *7113 + 19°'l 100° 7l"'60 69"'27 

 Poplar -7 174 + 19-0 90 66 "86 67*73 



Mean ... 69 -23 68 -50 

 Definitive difference + 0"*73. 



I attribute the coincidence of sign of the definitive differ- 

 ences to a fortuitous circumstance which would disappear by 

 combining a greater number of series, although it is in 

 favour of the duration of cooling of the electrified surface, in 

 the examples already mentioned. Moreover, these differences 

 are of so slight a kind that they may be reckoned amongst 

 the possible, nay, I may say probable, errors of observation. 



This nullity of influence of the electro- static state of the 

 porous or metallic parietes by which a calorific radiation is 

 brought about at the time of its cooling, reminds us of the re- 

 ciprocal indifference of electricity and of light when one of the 

 two fluids produce a chemical action *. It tends to a con- 

 clusion contrary to the opinion of some physiologists, that the 

 electric state, whether of the human body or of the atmosphere, 

 has no influence on the loss of animal heat in a given time, 

 and consequently none on the ceconomy of the general state 

 of health, nor on the functions of respiration and of digestion, 

 which are perhaps the only sources of this heat f. In my 

 experiments on organic parietes there has never been any ex- 

 udation of liquid on the exterior ; a change in the chemical na- 

 ture, and therefore in the temperature of this liquid, is not then 

 to be expected; nor must we look for phaenomena of evapora- 

 tion and of cooling, still less for internal lesions, the probable 

 or certain existence of which had been alleged in more than 

 one case by a skilful physicist %. 



# Archives of Electricity, vol. ii. p. 596. [ante, p. 254.] 



f See the remarks of M. Dumas on M. Dulong's researches on Animal 



Heat, and on the correction to be made of the coefficient of the calorific 



power of hydrogen. — Annates de Chimie et de Physique, 3 me Ser. t. viii. 



p. 180. (June 1843.) 



% Peltier's memoir on different kinds of fogs, SS. 28-30. Mem. de VAcad. 



de BruxeUes, t.xv. ; Annates de Chimie et de Physique, 3 me Ser. t. vi. p. 129. 



(Oct. 1842.) 



