

434 Miscellaneous Intelligence. 



times employ an equal mixture of spirit of sulphur, of sal-ammoniac, 

 of essence of rosemary, and onion-juice. " All volatile substances, we 

 see, which, in evaporating, render a certain portion of heat latent. 



Let us now seek the rational explanation of these facts. 



We have the formula ?n c /, which gives the quantity of heat con- 

 tained in any body. 



Let m be the muss expressed in kilogrammes, 

 c the specific heat of the body, 

 t its temperature. 



But here the factor m must be abstracted, because there is no con- 

 tact between the hand and the metal in fusion, and the experiment pre- 

 sents no difference, being made either with 10 kilogrammes of metal, 

 or with 1000 kilogrammes. The sensation which is felt is the same in 

 either case, and this is readily conceived, knowing the repulsive furce 

 of incandescent surfaces which is opposed to the contact of any body. 



The finder or the hand is then isolated in the midst of the mass in 

 fusion, and thus preserved from the disorganizing action of the incan- 

 descent matter. I repeat, that the mass must be abstracted. 



There remain the two factors c, /. I will suppose, and it is a suffi- 

 cient approximation, that the value of c =0" 15, and that of t zsz 1500 de- 

 grees, the temperature of the metal in fusion ; now the product of 1500 

 degrees X015zn225. Thus the epidermis of the experimenter would 

 only be exposed to 225 degrees of heat. Undoubtedly this is a re- 

 spectable quantity of caloric, but it is too high, as we shall see. 



There is no contact between the hand and the metal ; this, in my es- 

 timation, is a fact positively established. If there is no contact, the 

 heating can only take place by radialion, and it is enormous, it must be 

 acknowledged ; but if the radiation is annulled by reflexion, and it is 

 so, it is as if it did not exist, and, definitively, the operator is, so to say, 

 placed in normal conditions. 



I think that I have established, a long time ago, the fact that water in 

 the spheroidal state has the property of reflecting radiating heat,* and 

 that its temperature never attains that of its ebullition; whence it fol- 

 lows that the finger or the hand being humid, cannot rise to the tem- 

 perature of 100° Centig., the experiment not continuing long enough to 

 permit the humidity to evaporate entirely* 



To recapitulate what I have stated on this point, I say, — in passing 

 the hand into any metal in fusion, it becomes isolated ; the humidity 

 which covers it passes into the spheroidal state, reflects the radiating 

 caloric, and does not become heated enough to boil. This is all. 



I was right then in saying at the outset, this experiment, dangerous 

 in appearance, is almost insignificant in reality. 



I have often repeated it with lead, with bronze, &c, and always with 

 the same success.! 



* Nouvelle branche de Physique, or Etudes sur les Corps k PEtat sphSr* W» IT- 

 24 et 8eq. ami 132 et seq. See also our two letters to the Academie des Scien s, 

 dated the 14th and 21st of July, 1845. In the places indicated will be found the 

 explanation of thia phenomenon. 



f The experiments on the cast iron were made in the foundry of M. David«'u. at 

 La Villette; and, on the bronze, in that of ML Nerat, Rue Pierre-Levee. 1 am hupp 

 to have an opportunity of publicly thanking these gentlemen for their kind assistant 



