ELEMENTS 



OF 



CHEMISTRY. 



CHAPTER I. 



HEAT. 



THE objects of the material world are altered in their proper- 

 ties by heat in a very remarkable manner. The conversion of 

 ice into water, and of water into vapour, by the application of 

 heat, affords a familiar illustration of the effect of this agent in 

 changing the condition of bodies. All other material substances 

 are equally under its influence ; and it gives rise to numerous 

 and varied phenomena, demanding the attention of the chemical 

 inquirer. 



Heat is very readily communicated from one body to another ; 

 so that when hot and cold bodies are placed near each other, 

 they speedily attain the same temperature. The obvious trans- 

 ference of heat in such circumstances impresses the idea that it 

 possesses a substantial existence, and is not merely a quality of 

 bodies, like colour or weight ; and when thus considered as 

 a material substance, it has received the name caloric. It 

 would be injudicious, however, to enter at present into any 

 speculation on the nature of heat ; it is sufficient to remark 

 that it differs from matter as usually conceived, in several res- 

 pects. Our knowledge of heat is limited to the different effects 

 which it produces upon bodies, and the mode of its transmis- 

 sion; and these subjects may be considered without reference to 

 any theory of the nature of this agent. 



The subject of heat will be treated of under the following 

 heads : 



