75 



ON RADIANT HEAT. 



metal which it coated, yet the activity of the galvanic in- 

 fluence was interrupted, 



I am, Sir, 



Your obedient servant, 



CHARLES SYLVESTER. 



XVI. 



Remarks on Professor Leslie's Doctrine of radiant Heat; 

 with Experiments to show, that Caloric can pass through 

 transparent Media without heating them. By J. D. MAY- 

 COCK, Esq. 



To Mr. NICHOLSON. 

 SIR, 



LTHOUGH the most approved systematical writers Dense media 



on chemistry have not adopted the opinions "of Mr. Leslie, su PP osed »m- 



Ju • u- u •,-. • r + perv.ous to ra- 



respecting the manner in which an equilibrium of .tempera- dialing heat, 



ture is preserved among distant bodies, they have conceived 

 the result of his experiments sufficient to prove, that dense 

 media are impervious to caloric radiated from surfaces arti- 

 ficially heated. 



I shall not enter into a minute examination of the merits and caloric to 

 of the hypothesis, proposed in the " Experimental Inquiry," raise dietem- 

 for explaining what is commonly termed the radiation of ever y me dium 

 caloric; but shall content myself with reminding you, that il P as ses 

 it rests entirely on a supposition, that caloric passes through 

 no medium without first raising its temperature: the truth 

 of which Mr. Leslie considers as proved by the effects of 

 different skreens interposed, in his experiments, between 

 the thermometer and the source of heat. But as in the ex- 

 periments alluded to no regard was paid to time, I hold all 

 reasonings founded on them as fallacious and unsatisfac- 

 tory; and having myself obtained results, which favour 

 opinions very opposite to those advanced by the learned pro- 

 fessor, I take the liberty of communicating them to you. 



Exp. 1. I placed two metallic reflectors, 12 inches dia- Experiments 



meter, and 5J in. focal distance, fronting each other, and to P rove the 



. contrary. 



30 in. distant; I brought a differential thermometer into 



the 



