l!jl5.] Elements of Organic Katnre are covihincd. 173 



by combustion 0-239 -.vater, and 0G43 car'jonic acid, which gives 

 us per cent. 7-0l'3 hydrogen, and 43'724 carbon. It appears then 

 that starcli dried in a vacuum does not retain any water. Potatoe 

 starcli then is composed of 



Hvdrogen 7*0^4 



Carbon 43'481 , 



Oxygen 49-455 . ' 



100-000 



But we find that in amylate of lead the starch contains IS times 

 ns inuch oxygen as the base, and in the subamylate six times as 

 much. For 2-78 x 18 = 50-04, which differs very little from 

 49 4.55. Starch then contains either six or 18 atoms of oxygen. 

 It is therefore composed of 6 O + 7 C + 13 H, or of ISO + 

 21 C + 39 H. According to this statement, its composition 

 should be 



Hydrogen 7*090 



Carbon 43-327 



O.xygen 49-583 



This agrees well with tlie analytical result. 



Tbenard and Gay-Lussac found wheat starch composed of ("•77 

 liydrogon, 43-55 carl)on, and 49-68 oxygen. 20 ])arts of starch, 

 when incinerated in a platinum crucible, furnish 0*04(j of aslics, 

 consisting entirely of the earthy phosphates. Of course they ap- 

 pear to have been only mechanically mixed with the starch ; i)ut if 

 they be chemically combined, it is dinicult to determine the rela- 

 tion of their elementary atoms to those of the primary elements. 



licfore finishing this first set of experiments on the chemical 

 proportions in organic nature, I shall make some o!)scrvations rela- 

 tive to the substances which have come under our review. 



As to the nuinl)cr of elementary atoms of which an organic atom 

 is com])o«ed, it does not seem necessary that tiie most simple ratio 

 between the elements should express that number, 'i'luis it does 

 not seem necessary that an atom of starch ought to contain 6' O + 

 7 C 4- 13 H, or 2() elementary atoms; it is just as possible that it 

 contains three times that number, and that it is upon such a com- 

 poj-ition that the proportion between the starch and oxide of lead 

 in the neutral amylate depends. In tlie same way, we may say, 

 that gallic acid is composed of 3 O + f! C + (T\\, and not oiO + 

 2 C 4 2 H. The great number of elementary atoms combined in 

 a compound atom does not constitute any objection to this conclu- 

 sion ; for if the atom of starch contains in fact 78 elementary 

 atoms, we may, on the other side, point out in organic nature 

 compound atoms of the second and third order, which contain a 

 still greater number of clement'. Thus the -atom of crystallized 

 nltmi coutaiii'. one alonj of jvitas^ium, two of aluminium, eight of 

 i-ulphur, 80 of oxygen, and Oi'> of hydrogen, cun'jtitu'>it;g altogether 



Voi„ V. N° IV. S 



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