8 The Chemical Statics of Organised Beings. 



of azote, which may be represented by 3 molecules of hydrogen 

 weighing 3, and by 1 molecule of azote weighing 14. 



Thus, as if the better to show all her power, nature operates, 

 in the business of organisation, upon a very small number only 

 of elements combined in the most simple proportions. 



The atomic system of the physiologist revolves on these four 

 numbers: 1, 6, 7, 8. 1 is the molecule of hydrogen ; 6, that of 

 carbon; 7, or twice 7, i.e. 14, that of azote; 8, that of oxygen. 



These numbers should always be associated with these names, 

 because for the chemist there can exist no abstract hydrogen, 

 nor carbon, nor azote, nor oxygen. They are beings in their 

 reality which he has always in view; it is of their molecules that 

 he always speaks ; and to him the word hydrogen depicts a 

 molecule which weighs 1 ; the word carbon, a molecule which 

 weighs 6 ; and the word oxygen, a molecule which weighs 8. 



Composition of the Air. — Does atmospheric air, which per- 

 forms so great a part in organic nature, also possess as simple a 

 composition as water, carbonic acid, and ammonia? This is the 

 question which M. Boussingault and I have recently been 

 studying. Now, we have found that, as the greater number of 

 chemists have thought, and contrary to the opinion of Dr. Prout 

 to whom chemistry owes so many ingenious views, air is a 

 mixture, a true mixture. 



In weight, air contains 2,300 of oxygen for 7,700 of azote; in 

 volume, 208 of the first for 792 of the second. The air, besides, 

 contains from 4 to 6 10,000ths of carbonic acid in volume, 

 whether it be taken at Paris or in the country. Ordinarily, it 

 contains 4 10,000ths. Moreover, it contains a nearly equal 

 quantity of the carburetted hydrogen gas which is called marsh 

 gas, and which stagnant waters disengage perpetually. 



We do not speak of aqueous vapour, which is so variable ; 

 of oxide of ammonium and of nitric acid, which can only have 

 a momentary existence in the air because of their solubility in 

 water. 



The air, then, is constituted of a mixture of oxygen, azote, 

 carbonic acid, and marsh gas. 



The carbonic acid in it varies, and indeed greatly, since the 

 differences in it extend almost from the simple to the double, 

 from 4 to 6 10,000ths. May this not be a proof that plants 

 take from the air this carbonic acid, and that animals take back 

 a part from it ? in a word, may not this be a proof of that equi- 

 librium of the elements of the air attributed to the inverse ac- 

 tions which animals and plants produce upon it? 



It has, indeed, been long since remarked, animals borrow 

 from the air its oxygen, and give to it carbonic acid ; plants, in 

 their turn, decompose this carbonic acid, in order to fix its car- 

 bon and restore its oxygen to the air. 



As animals breathe continually ; as plants breathe under the 



