70 THE THEORY OF IONS 



is then C 5 H 15 NO 3 . Cholin may be robbed of four 

 atoms of H by OH ions or other oxidising agents, 

 such as an aldehyde and an acid. The result is 

 Betaine, C 5 H n N0 2 , a non-poisonous substance found 

 in beetroot, other plants, and in mollusca. Betaine 

 is also an amido-acid, tri-methyl-glycocoll or oxy- 

 neurin, and is derivable from hydroxy-ammonium- 

 alcohol. If the carboxyl-group of alanine or amido- 

 propionic acid is displaced by sulphonyl it forms 

 Taurine, C 2 H 7 NS0 3 . Taurine and cholin occur in 

 the bile as taurocholic and glycocholic acids. All 

 these are products of catabolic processes in the 

 organism. 



The mode of formation of all the urea in the 

 organism is not positively known ; but that some 

 of it is formed from ammonia in the liver is proved 

 beyond a doubt, and it is considered to be formed 

 partly from ammonium carbonate and partly from 

 carbamic acid or other amino-acids (leucin, glycocoll 

 or asparagine) or extractives (creatin, creatinine), 

 with carbamic acid as an intermediate product. 

 Carbamic acid is not known in a free state, but only 

 in combination as salts. We have seen how it may 

 arise from formic acid, CH 2 2 , by the NH 2 ion dis- 

 placing an H atom and joining the carboxyl, CH 2 2 

 + NH 2 = H+CH 3 N0 2 or COOH-NH 2 . It may also 

 be formed from carbonic acid, CH 2 3 , by NH 2 dis- 

 placing a hydroxyl. Carbonic acid is dibasic, and 

 may have one or both its hydroxyls displaced by an 

 amido-group, forming amides or aminic acids. 

 When both of the OH ions are displaced by am- 

 monia-radicals it forms urea. 



