810 LETTEES ON NATURAL MAGIC. 



Blagden entered a room in which the air had a 

 temperature of 198 Fahr., and remained ten 

 minutes ; but as the thermometer sank very 

 rapidly, they resolved to enter the room singly. 

 Dr. Solander went in alone, and found the heat 

 210, and Sir Joseph entered when the heat was 

 211. Though exposed to such an elevated tem- 

 perature, their bodies preserved their natural 

 degree of heat. Whenever they breathed upon 

 a thermometer it sank several degrees : every 

 expiration, particularly if strongly made, gave a 

 pleasant impression of coolness to their nostrils, 

 and their cold breath cooled their fingers when- 

 ever it reached them. On touching his side, Sir 

 Charles Blagden found it cold like a corpse, and 

 yet the heat of his body under his tongue was 

 98. Hence they concluded that the human 

 body possesses the power of destroying a certain 

 degree of heat when communicated with a certain 

 degree of quickness. This power, however, 

 varies greatly in different media. The same per- 

 son who experienced no inconvenience from air 

 heated to 211, could just bear rectified spirits of 

 wine at 130, cooling oil at 129, cooling water 

 at 123, and cooling quicksilver at 117. A 

 familiar instance of this occurred in the heated 

 room. All the pieces of metal there, even their 

 watch-chains, felt so hot that they could scarcely 

 bear to touch them for a moment, while the air 

 from which the metal had derived all its heat 

 was only unpleasant. Messrs. Duhamel and 

 Tillet observed, at Rochefoucault in France, that 

 the girls who were accustomed to attend ovens 

 in a bakehouse were capable of enduring for ten 

 minutes a temperature of 270. 



The same gentlemen who performed the expe- 





