WHAT AIR is. 159 



of known substances, and on that account used for 

 filling balloons, which, because of their lightness, 

 rise in the air and carry up men and their instruments 

 of observation; or be it gold or platinum, which, 

 when in the solid state, are the heaviest of known 

 substances, still if it be in the state of air, all its pro- 

 perties, as solid or as liquid matter, are subdued and 

 suspended by heat, when it is in the state of air, 

 excepting gravitation or weight. The direct action 

 of that is also suspended, and a heavy metal may, by 

 being reduced to the state of air or vapour, be made to 

 float in the atmosphere, and to pass upward rather than 

 downward. But that is owing to the dispersion of 

 the minute parts of it through much more space 

 than they occupied in the solid or the liquid form. 

 Could all those scattered particles be collected, they 

 would at all times weigh exactly the same ; and if 

 they were made again to occupy just the same space 

 as the solid or the liquid, all the properties of the 

 solid or the liquid would return, and it would be the 

 same identical substance that it was before the action 

 of heat turned it into air. 



In the actions or changes that take place in nature 

 (for action is but another name for change) the state 

 of air is of the utmost consequence ; and it is highly 

 probable, nay, absolutely certain, that, without that 

 state there would be no action whatever. The state 

 of air is the end of every thing old and the beginning 

 of every thing new. The matter of which any 

 thing all things, is composed is altogether inde- 

 structible by any natural cause; and, therefore, the 

 only way in which any thing can be destroyed is by the 

 destruction or complete suspension of all its peculiar 

 properties, by the conversion of it into air through 

 the action of heat. While it retains all the former 

 properties, it is the former substance -, and while it 

 retains some of them, after others have ceased to be 

 apparent, it is the ruin of the former substance ; but 

 when the whole of the former properties are sus- 

 pended, and the substance (still identically the same 



