xvn MOLECULAR ARCHITECTURE 443 



a chemical equation. Other early analyses were made by Gay- 

 Lussac and Thenard (1810), who discovered the existence of 

 carbohydrates, by Berthollet (1809), by de Saussure (1807 and 

 1814), who analysed alcohol and ether, by Berzelius (1815), 

 who first expressed his organic analyses by means of formulas, 

 and finally by Liebig (1831), to whom belongs the credit of 

 perfecting the methods of organic analysis. 



B. THE STRUCTURE OF SALTS. 



Mayow, in 1674, showed that salts contained an acid and 

 a base, which might be set free again by the action of a stronger 

 acid or base. Lavoisier regarded salts as compounds of two 

 oxides, namely, the acid oxide of a non-metal and the basic oxide 

 of a metal. Berzelius (1819) adopted this dualistic theory, but 

 recognised that binary compounds could be formed which 

 contained no oxygen, and (at a later date) that salts might be 

 formed by uniting two hydrides or two sulphides. He suggested 

 that all compounds were held together by the electrical attrac- 

 tion between oppositely charged components ( Berzelius' dualistic 

 or electro-chemical theory]. 



C. THE THEORY OF RADICALS. 



Berzelius's electro-chemical theory could not readily be applied 

 to organic compounds, which were not amenable to electrolysis. 

 In order to bring them into his scheme Berzelius (1819) adopted 

 Lavoisier's view that inorganic compounds were derived from 

 simple elementary radicals, but organic compounds from 

 compound radicals, containing two or more different elements. 

 The most important radicals were : 



Cyanogen . . . CN or Cy Gay-Lussac, 1815. 



[Ammonium . . NH 4 or Am Ampere, 1816. 



-j Ammonia . . NH 3 



(Amide . . . NH 2 or Ad Berzelius, 1832 



(Ethyl . . . C 2 II 5 orEt Liebig, 1834^ 



! Aetherin (ethylene) C 2 H 4 or Ae Dumas and Boullay, 1827. 



( " Acetyl " now C 2 H 3 O) C 2 H 3 Liebig, 1839. 



/Methylene . . CH 2 Dumas and Peligot, 1834. 



\Methyl . . . CH 3 or Me Dumas and Peligot, 1834. 



/Benzoyl . . . C 7 H 5 O or Bz Wohler and Liebig, 1832. 



\Pikramyl . . C 7 H 6 or Pk Berzelius, 1843. 



