ANIMAL HEAT. 679 



tained without inconvenience. Many instances are on record, of a heat of 

 from 250 to 280 being endured in dry air for a considerable length of time, 

 even by persons unaccustomed to a particularly high temperature ; and per- 

 sons whose occupations are such as to require it, can sustain a much higher 

 degree of heat, though not perhaps for any long period. The workmen of 

 the late Sir F. Chantrey have been accustomed to enter a furnace in which 

 his moulds were dried, whilst the floor was red-hot, and a thermometer in the 

 air stood at 350 ; and Chabert, the " Fire-king," was in the habit of entering 

 an oven, whose temperature was from 400 to 600. It is possible that these 

 feats might be easily matched by many workmen who are habitually exposed 

 to high temperatures; such as those employed in Iron-foundries, Glass- 

 houses, and Gas-works. In all these instances, the dryness of the air facili- 

 tates the rapidity of the vaporization of the fluid, of which the heat occasions 

 the secretion by the Cutaneous glands; and the large amount of caloric which 

 becomes latent in the process, is for the most part withdrawn from the body, 

 the temperature of which is thus kept down. Exposure to a very elevated 

 temperature, however, if continued for a sufficient length of time, does pro- 

 duce a certain elevation of that of the body ; as might be expected from the 

 statements already made in regard to the variation in the heat of the body 

 with changes in atmospheric temperature ( 886). In the experiments of 

 MM. Berger and Delaroche, it was found that, after the body had been ex- 

 posed to air of 120 during 17 minutes, a thermometer placed in the mouth 

 rose nearly 6 degrees above the ordinary temperature; it may be remarked, 

 however, that as the body was immersed in a close box, from which the head 

 projected (in order to avoid the direct influence of the heated air on the tem- 

 perature of the mouth), the air had probably become charged with the vapour 

 exhaled from the surface, and had therefore somewhat of the effects of a moist 

 atmosphere. At any rate, the temperature of the body does not appear to 

 rise, under any circumstances, to a degree very much greater than this. In 

 one of the experiments of Drs. Fordyce and Blagden, the temperature of a 

 Dog, that had been shut up for half-an-hour in a chamber of which the tem- 

 perature was between 220 and 236, was found to have risen from 101 to 

 about 108. MM. Delaroche and Berger tried several experiments on differ- 

 ent species of animals, in order to ascertain the highest temperature to which 

 the body could be raised without the destruction of life, by inclosing them in 

 air heated from 122 to 201, until they died: the result was very uniform, 

 the temperature of the body at the end of the experiment only varying 

 in the different species between 11 and 13 above their natural standard: 

 whence it may be inferred, that an elevation to this degree must be fatal. 

 This elevation would be attained comparatively soon in a moist atmo- 

 sphere ; partly because of the greater conducting power of the medium ; 

 but principally on account of the check which is put upon the vapor- 

 ization of the fluid secreted by the skin. Even here, however, custom 

 and acquired constitution have a very striking influence ; for whilst the in- 

 habitants of this country are unable to sustain, during more than 10 or 12 

 minutes, immersion in a vapour-bath of the temperature of 110 or 120, the 

 Finnish peasantry remain for half-an-hour or more in a vapour-bath, the tem- 

 perature of which finally rises even to 158 or 167. Accurate experiments 

 are yet wanting, to determine the influence of humidity on the effects of cold 

 air. From experiments on young Birds incapable of maintaining their own 

 temperature, of which some were placed in cold dry air, and others in cold air 

 charged with moisture, it was found by Dr. Edwards that the loss of heat was 

 in both instances the same; the effect of the evaporation from the surface in 

 the former case, being counter-balanced in the latter by the depressing influ- 

 ence of the cold moisture. This influence, the existence of which is a mat- 



