REFRIGERATION. 343 



'Common feelings, who possess common sense, 

 to be told, by the most enlightened che- 

 mists and experimental philosophers, as they 

 call themselves, that none but ignorant 

 fools, if any there are so foolish, dare to 

 think so.* 



So long ago as the year 1684, was found in 

 the essays of 1'Academie del Cimento, a paper 

 which has been translated, to shew the nature 

 and properties of cold ; and the recent experi- 

 ments lately made by Mon. PJCTET decidedly 

 prove, that what is called cold, may as easily 

 be reflected from snow and ice, as what is call- 

 ed heat, from aflame of fire. Pictet placed two 

 concave mirrors, made of tin, at the distance of 

 ten feet and a half from each other ; a very de- 

 licate thermometer was put into the focus of 

 one, and a glass mattrass, full of snow, into the 

 focus of the other ; the mercury in the thermo- 

 meter immediately sunk several degrees ; and 

 when the mattrass was removed, which contain- 

 ed the snow, when the rays of snow ceased to 



* I must refer the reader to the chapter on Sensation. I 

 hope that he is, by this time, sufficiently acquainted with the 

 difference which exists between impression and sensation, not 

 to know, in speaking of ice being cold, and of fire being 

 hot, that these bodies are not cold or hot essentially or per se, 

 but only cause impressions which excite the sensations of cold 

 and of heat. 



