22 ON THE STUDY OF 



some previous knowledge of another branch of 

 science to which they have frequent reference, 

 I shall, in a very few words, explain to you its 

 nature and import I allude to chemistry. 



Chemistry is that science or art, the object of 

 which is to ascertain the component or consti- 

 tuent parts of all substances; and what effects 

 are produced on them by change of temperature, 

 or by their mutual action upon each other; and 

 the mode arid laws by which those changes are 

 effected. 



As opposed to natural history, chemistry looks 

 into the most minute and interior structure of 

 substances, the changes to which they are sub- 

 ject, and the uses to which the constituent parts 

 separately or in combination can be applied. 

 Natural history explains the external character 

 and appearances of those substances as, upon 

 first examination, they strike the senses, their 

 classification and the order in which they are 

 arranged, the situation in which they are ordina- 

 rily to be found, and the probable uses for which 

 they were created. 



By the above definition of chemistry, it must 

 be considered a science of universal application; 

 since it enters into all the most minute operations 

 to which natural bodies are subject, and into a 

 full explanation of the different changes and ope- 

 rations which are constantly taking place in the 

 grand laboratory of nature ; or which, in imitation 



