472 Life of Coimt Rumford. 



Count sets forth. He reminds us that there are but 

 three forms under which all sensible bodies are found to 

 exist, that of a solid, that of a fluid, and that of gas ; 

 and that every substance with which we are acquainted 

 may exist under all those three forms alternately, the 

 condition for either form being dependent upon tem- 

 perature. He works out elaborately his hypothesis of 

 the existence of intense heat in the midst of cold liquids. 

 He recognizes two ways in which philosophers, like 

 other men, may be excited to action and induced to 

 engage zealously in the investigation of any curious 

 subject of inquiry, "they may be enticed, and they 

 may be provoked. It will probably not escape the pene- 

 tration of my reader that I have endeavored to use both 

 these methods. I am well aware of the danger that 

 attends the latter of them ; but the passionate fondness 

 that I feel for the favorite objects of my pursuits fre- 

 quently hurries me on far beyond the bounds which 

 prudence would mark to circumscribe my adventurous 

 excursions." 



Count Rumford made an eighth Essay on the 

 Propagation of Heat in various Substances, by a 

 reprint of two papers, which first appeared in the 

 Philosophical Transactions, the one having been read 

 before the Royal Society in 1786, and the other, for 

 which he received the Copley Medal of the Society, in 

 1792. He gives in it an account of the beginning of 

 his experiments on the conducting power of the Torri- 

 cellian vacuum. These he had made while on a journey 

 with the Elector, at Mannheim, in July, 1785, in pres- 

 ence of Professor Hemmer, of the Electoral Academy 

 of Sciences, of that city, and of Charles Artaria, mete- 

 orological instrument maker, who assisted him. His 



