10 CONCERNING- SEGT. II. 



AIR is found in a considerable degree in water, 

 in plants, and in fruits. It may be almost demon- 

 strated (says one) that the vegetable nourishment is 

 principally in the air : The tree Sedum suspended, 

 lives and grows for years by air through its moisture. 



How necessary this element of air is to man, the 

 commonest observation evinces. Deprived of air, 

 life is quickly lost, and in a depraved state of it, 

 runs fast to sickness and death, Thus plants are 

 found to flourish in a free and open air, and grow 

 pale and languish in the contrary. But air is not 

 only necessary for the leaves of plants to breathe in, 

 their roots require it : Plants will not do well if the 

 soil is too much bound for the air to penetrate freely 

 about them. 



The sickliness of housed plants has been said to be 

 owing greatly to want of motion. But the want of 

 fresh air, is undoubtedly the chief cause ; for pure 

 air is fraught with animating principles, and by its 

 attenuating and elastic properties, separates the gross 

 juices, keeps the sap in motion, and the plants in 

 health. 



Air conveys to the organs of smelling, all those 

 grateful scents, which plants, flowers and fruits pro- 

 duce, and we are greatly regaled, and refreshed by 

 them. 



If it be asked, what air is, and of what it con- 

 sists? It may be answered, Particles of wet and dry 

 bodies volatilized; and rendered elastic by fire. The 

 air or atmosphere that surrounds our earth, contains 

 a mixture of all the active volatile parts of the whole 

 habitable world ; that is, of all vegetables, minerals 

 and animals. Whatever perspires, corrupts or ex- 

 hales, impregnates the air ; which, being acted upon 

 by the solar fire, produces within itself, all sorts of 

 chemical operations, dispenses again those salts and 



