<g|g ON THE NATURE OF HEAT. 



by the hj'pothesis of Homberg and Boerhaave. It may in- 

 deed be observed, that while the opinion of the materiality 

 of (JkloHc has had many adherents, and received much con- 

 sider^ation, the hypothesis of Bacon has probably been too 

 much neglectej^; nay, it has even been held up to ridicule 

 and contempt, as a ** delusive dream," or as a ** labyrinth 

 of perplexities." Probably the reason of this censure has 

 been just given ; had the opinion obtained the consideration 

 which it nierils, it would possibly have long since ceased to 

 be this labyrinth of perplexity. 



I trust therefore, that a few observations on this subject 

 will not be altogether unwelcome: no apology can be re- 

 quired for their iinperfeciioijfa, I shall commence with a 

 few remarks on the prevailing opinion, and shall then give 

 a concise view of what may be termed the hypothesis of vi- 

 bration, 



1, Sotirces of caloric. 



Sources of Scarcely any circumstance can aiford more forcible ob- 



heat. jection to the hypothesis of material caloric, than some of 



the means of producing an increase of temperature. Every 

 one is acquainted with the important researches of Bogle, 

 Romford^ and Davy, on this subject. Their experiments 

 prove, that lieat may be produced by friction in circum- 

 stances, where no source of it, considered as a material 

 agent, can be discovered or suspected. 



But these facts have been so often urged as imcompatible 

 with the supposition of material caloric, that it is needless 

 to enter farther into the discussion of this point. I wish ra- 

 ther to avail myself of this opportunity, to consider other 

 parts of the doctrine. 



Under this head it may indeed be added, that the ex- 

 citation of heat, in the operations of electricity and galva- 

 nism, has not been explained. There is also much difficulty 

 in accounting for the production of heat in some instances of 

 cpmbastion^, and of other chemical actions. 



♦ Thomson, yol. I, p. 575 et seq. 3d cd* 



2. 3Iotion 



