LIGHT ALIMENT OF VEGETATION. 105 



dently demonstrable. Thus, when a small quantity of concen- 

 trated nitric acid mixed with a few drops of sulphuric acid, is 

 poured on an ounce of oil of turpentine, instant inflammation, 

 and most resplendent combustion ensues. 



Nitric acid is composed of 1 atom nitrogen 5 atoms oxygen. 



Sulphuric acid ditto, 2 atoms sulphur 3 do. of oxygen ; oil of turpentine 

 contains of Carbon 14 equivalents oxygen 1 eq. hydrogen 10 eq. 



Doctor Ure. 

 Atmospheric air 4 nitrogen 1 oxygen. 



Thus we have all the constituents of light (according to the 

 views here set forth) present at one time. 



The influence of light on vegetation is so well established, 

 that it is scarcely necessary to trespass on the reader with fur- 

 ther observations. 



The experiments conducted with so much accuracy by Sir H. 

 Davy, Mr. Knight, and others, to ascertain the aliment of plants, 

 their consumption and growth in a given period, sufficiently prove 

 that they owe to light not only all their beauty, but much of their 

 substance ; for it was found that a plant originally weighing 

 not more than 1^ Ib. placed in a tub containing garden mould, 

 the weight of which was accurately noted, the plant was regu- 

 larly watered with distilled water for upwards of two years, 

 while it was exposed to the sun's rays in the day, and carefully 

 inclosed with glass at night ; at the end of the period the mould 

 was taken out and weighed, when it was ascertained that out 

 of 1501b. in weight it had not lost more than 6 or 7 ounces 

 (the dust accidentally blown away) ; while the plant had in- 

 creased to about 67 pounds, having no other aliment than light, 

 and water, and atmospheric air. It is easy to conceive that 

 from the water hydrogen and oxygen were in part derived, and 

 nitrogen from the air as well as oxygen ; but the CARBON did 

 not exist in the air or water to such extent, and could only be 

 produced by the action of light in combining the three essen- 

 tial rays in conjunction with the constituents of water and air, 

 to produce carbon ; for it is fully acknowledged that vegetable 

 bodies which grow in the dark, and where LIGHT is totally 



