OBJECTS.] INTRODUCTORY. 73 



circumstances, and can be traced by it whatever shape 

 they may take. If this is true it follows that, in the 

 order of nature, matter is indestructible : the 

 quantity of it neither increases nor diminishes. 



Hence it follows that natural things and artificial 

 things resemble one another in one respect. It is 

 true of both that the matter of which they are com- 

 posed is never destroyed and never increased ; and 

 therefore the order of events in nature as much 

 consists in the joining together and putting apart of 

 natural bodies by natural agencies, as the order of 

 events in the artificial world consists in the joining 

 together and the putting apart of natural bodies by 

 human agencies. 



51. Simple Mixture. 



In order to learn the manner in which water may 

 be broken up into its elements or decomposed, 

 you must turn to the Primer on Chemistry. But as a 

 preliminary to the study of that science, it may be 

 useful to consider some simple cases of composition 

 and decomposition which are exemplified by water. 



If half a pint of water, coloured by putting a little 

 ink into it, is added to the same quantity of clean 

 water, the two will readily mingle ; the total quantity of 

 water will be a pint ; and its colour will be just half as 

 dark as that of the coloured half-pint. This is a case 

 of simple mixture. The volume of the mixture 

 equals the sum of the volumes of the things mixed, 

 and there is no change in the properties of these things. 

 So when water evaporates, the gaseous water or 

 vapour mixes with the air in the same way, the mole- 

 cules of the one body dispersing themselves between 



