494 METEOROLOGY. RAIN. 



into the constitutu/n of vegetables, it is discovered in the manure 

 which proceeds more >jpecially from animal remains ; for vegeta- 

 bles, to thrive, must receive azotized aliment b}- 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 ? 



If we no"' turn to the possible sources or magazines of azote, ^e 

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

 there is in truth l)ut one, tlie atmosphere. It is therefore extremely 

 probable that all living beings have previously obtained their azote 

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

 thence derived their carbon.* 



The most reasonable supposition in the actual stale 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 efiects 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 n-aclions of which 

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

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

 with calcareous rocks, should suffer decomposition, pass into the 

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

 to undergo dilfiision in the state of vapor throuirh the atmosphere. 

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

 flash of liiihtning, 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 office of so much importance will per- 

 haps be ac{;orded reluctantly to the electricity <tf tlie clouds ; but ia 

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

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

 33t only every day, but every hour, and even every minute of everj 



♦ Boussingaiili, .\iiii.nles ile Oilmie, t IxiL J839. 



