460 DistrihutioJi of the':,Atmosphere. 



decomposing the atmosphere, and by making it essential to 

 vegetable life, to receive for its nourishment what is rejected by 

 animals, and is destructive to their nature. It clearly can be 

 demonstrated that plants, on this principle, are as active agents 

 as animals. It is evident, that in them there are a regular 

 inspiration and expiration of atmosphere, vv^hich in the circu- 

 lation of their fluids becomes decomposed. They retain the 

 carbon, hydrogen, carburetted hydrogen, and nitrogen,, as 

 absolutely necessary to their support, though destructive to 

 animals, and, by respiration, discharge the oxygen again, 

 retaining so much of the latter as is necessary to stimulate 

 the others, and form the sugar and acids which are found in 

 vegetables. But this is not the only agency of plants in 

 purifying the atmosphere, they have also the property (assisted 

 by solar rays) of decomposing watei', the component parts of 

 which are 12 of hydrogen, and 88 of oxygen in every 100 

 parts of the fluid by weight, and 67 hydrogen and 33 oxygen 

 in every 100 parts by measure. In this decomposition the 

 hydrogen is retained, and, combining with the nitrogen and 

 carbon of the atmosphere and soil, forms the wax, gum, oil, 

 and resin in vegetables ; whilst the oxygen, volatilised by the 

 heat of the sun, is given out, by expiration, in the form of 

 oxygen gas. So that, by these several operations (which gar- 

 deners, by attending the lectures at a mechanics' institution, 

 would have opportunities of seeing illustrated by experiments), 

 whilst Nature gives nourishment and materials of growth to 

 the vegetable world, she at the same time, by their agenc}'^, 

 renovates that vital principle in the atmosphere necessary for 

 the support of animal life ; and thus, reciprocally acting on the 

 same principle, they correct and balance the effects of each 

 other, so as to keep up that uniform equilibrium and salubrity 

 of the atmosphere, which, though it is the receptacle of all 

 vapour and volatilised productions, yet is so renovated by this 

 system and so mingled together by its constant circulation 

 and the affinity of the lighter and heavier gases for each 

 other, that it is always found to be sensibly the same with 

 regard to its intimate qualities in every situation. 



In contemplating so beautiful a system, the several other 

 agencies of plants in giving it effect, and the order and regu- 

 larity with which it ever has continued in action, though it 

 must make man see the weakness and imperfections of his 

 own designs, yet, while he feels his insufficiency, he is lost in 

 the fulness of infinite wisdom, which is everywhere employed 

 for his welfare and safety. 



I am, Sir, &c. . 

 Bristol, November 30. 1826. P. Masey, Jun. 



