494 METEOROLOGY. RAIN. 



into the constitution of vegetables, it is discovered in the manure 

 which proceeds more >3pecially from animal remains ; for vegeta- 

 bles, to thrive, must receive azotized aliment by their roots. We 

 thus come to apprehend that plants supply animals with their azote, 

 and that these restore it to plants when the term of their existence 

 is accomplished ; we are led to discover, in a word, that living or- 

 ganic matter derives its azote from dead organic matter. 



This view leads us to conclude that the amount of living matter 

 on the surface of the globe is restricted ; that its limits are in some 

 sort determined by the quantity of azote in circulation among organ- 

 ized beings ; but the question must be viewed from a loftier emi- 

 nence, and we must ask what is the origin of the azote which enters 

 into the constitution of organic matter considered as a whole 1 



If we now turn to the possible sources or magazines of azote, we 

 shall find, setting aside organized beings and their remains, tnat 

 there is in truth but one, the atmosphere. It is therefore extremely 

 probable that all living beings have previously obtained their azote 

 from the atmosphere, just as it seems very certain that they have 

 thence derived their carbon.* 



The most reasonable supposition in the actual state of science, is 

 to consider the ammoniacal vapors diffused through the atmosphere 

 as the prime source of the azotized principles of vegetables, and 

 then through them of animals ; a consequence of which hypothesis 

 would be to assume with Liebig, that carbonate of ammonia existed 

 in the atmosphere before the appearance of living things upon the 

 face of the earth. 



The phenomena and effects of thunder-storms appear to me cal- 

 culated to support this opinion. It is known, in fact, that so often 

 as a succession of electrical sparks passes through moist air, there 

 is formation and combination of nitric acid and ammonia. Now ni- 

 trate of ammonia is one of the constant ingredients in the rain of 

 thunder-storms. But nitrate of ammonia, being a fixed salt, cannot 

 exist in the atmosphere in the state of gas or vapor ; and then it is 

 not the nitrate, but the carbonate of ammonia that has been signal- 

 ized in the air. In bringing to mind the series of reactions of which 

 I have spoken, it is not difficult to perceive how the nitrate of am- 

 monia, precipitated in thunder-showers, and thus brought into contact 

 with calcareous rocks, should suflfer decomposition, pass into the 

 state of carbonate on the return of fair weather, and become fitted 

 to undergo diffusion in the state of vapor through the atmosphere. 

 We should in this way be led to regard the electrical agency, the 

 flash of lightning, as the means by which the azote of the atmosphere 

 is made fit' for assimilation by organized beings. In Europe, where 

 thunder-storms are rare, an oflice of so much importance will per- 

 haps be accorded reluctantly to the electricity of the clouds ; but ia 

 tropical countries no difficulty would probably be felt on the matter. 

 In the torrid zone, thunder-storms happen in one place or another 

 iSt only every day, but every hour, and even every minute of eTery 



* Bonssingault, Annales de Chimic, t Izxi 1838. 



