302 LETTEES ON NATURAL MAGIC. 



been used in place of boiling water. A solution 

 of spermaceti or sulphuric ether, tinged with 

 alkanet root, which becomes solid at 50 of Fah- 

 renheit, and melts and boils with the heat of the 

 hand, is supposed to be the substance which is 

 used at Naples when the dried blood of St. 

 Januarius melts spontaneously, and boils over 

 the vessel which contains it. 



But even when the fluid requires a high tem- 

 perature to boil, it may have other properties, 

 which enable us to plunge our hands into it with 

 impunity. This is the case with boiling tar, 

 which boils at a temperature of 220, even higher 

 than that of water. Mr. Davenport informs us, 

 that he saw one of the workmen in the Royal 

 Dock-yard at Chatham immerse his naked hand 

 in tar of that temperature. He drew up his 

 coat-sleeves, dipped in his hand and wrist, bring- 

 ing out fluid tar, and pouring it off from his hand 

 as from a ladle. The tar remained in complete 

 contact with his skin, and he wiped it off with 

 tow. Convinced that there was no deception in 

 this experiment, Mr. Davenport immersed the 

 entire length of his fore-finger in the boiling 

 cauldron, and moved it about a short time before 

 the heat became inconvenient. Mr. Davenport 

 ascribes this singular effect to the slowness with 

 which the tar communicates its heat, which he 

 conceives to arise from the abundant volatile 

 vapour which is evolved, " carrying off rapidly 

 the caloric in a latent state, and intervening be- 

 tween the tar and the skin, so as to prevent the 

 more rapid communication of heat." He con- 

 ceives also, that when the hand is withdrawn, 

 and the hot tar adhering to it, the rapidity with 



