I860.] 



on the Chemical Action of the Solar Rays. 



215 



light metres. Hence, we see how much the sun's chemical action varies 

 on tlie different planets ; the superior planets receiving so small a 

 portion as to render it impossible that the kind of animal and vegetable 

 life which we here enjoy can there exist. 



Table III. — Chemical Action produced by Direct Sunlight on 

 each Planet. 



Mercury 

 Venus . 

 Earth . 

 Mars . 

 Jupiter . 

 Saturn . 

 Uranus 

 Neptune 



Mean Distances. 



0-387 

 0-723 

 1000 

 1-524 

 5-203 

 9 539 

 19-183 

 30-040 



Chemical 

 Light Degrees, 



2125-0 



608-9 



318-3 



137-1 



11-8 



3.5 



1-0 



'0-4 



Action in 



Liglit Metres. 



235.4 



67-5 



35-3 



15-2 



1-2 



0-4 



0-1 



0-04 



Interesting conclusions can be drawn from these facts, concerning 

 the distribution of the chemical rays on the surface of our earth in 

 different latitudes, and at different elevations above the sea's level. The 

 farther removed a situation is from the level of the sea, the higher up 

 in the atmosphere it is placed, the greater amount of chemical action 

 it will receive. Thus, in the highlands of Thibet, where corn and 

 grain flourish at a height of from 12,000 to 14,000 feet, the chemical 

 action of the direct sunlight is li times as great as in the neighbouring 

 lowland plains of Hindostan. In the same way we can calculate for 

 any point of the earth's surface whose latitude is known, the amount 

 of chemical action which the direct sunlight effects at any given time 

 of day or year. In Table IV. the numbers represent the chemical 



Table IV. — Chemical Action effected by Direct Sunlight in 

 One Minute on the Vernal Equinox at 



A. Melville Island. 



B. Rejkiavik, Iceland. 



C. St. Petersburg. 



D. Manchester. 



E. Heidelberg. 



F. Naples. 



G. Cairo. 



<i2 



