THE ORGANIC NON-NITROGENOUS ACIDS. 95 



formed into an acid of the acrylic series (see below), viz., a-crotonic 



acid : 



CH 3 .CH(OH).CH 2 .COOH = 2H 2 O + CH 3 CH = CH.COOH 



o-Capronic acid. 



The acids of the acrylic series can be represented by the general 

 formula C n H 2n _ 2 O 2 . Representatives of these are the a-capronic 

 acid, just referred to, and oleic acid, which as a triglyceride rep- 

 resents a most important constituent of many of the vegetable and 

 animal fats. On heating with hydriodic acid and red phosphorus to 

 a temperature of 210 C., oleic acid takes up two atoms of hydro- 

 gen, and is thus reduced to stearic acid : 



CH 3 .(CH 2 ) 13 .CH = CH.CH 2 .COOH + 2H = CH 3 .(CH 2 ) 16 .COOH 

 Oleic acid. Stearic acid. 



On treating with nitrous acid, in statu nascendi, it is transformed 

 into the solid elaidinic acid, which is isomeric with oleic acid and 

 belongs to the same series. 



The dibasic acids of -the oxalic series can be represented by the 

 formula C w H 2n _ 2 O 4 . They include oxalic acid, succinic acid, and 



tlutaric acid, of which the two latter are generally met with in the 

 >rm of their amides, viz., as asparaginic acid and glutaminic acid, 

 respectively. In this form they are invariably obtained, together 

 with oxalic acid, as decomposition-products of most albumins. 

 Oxalic acid and succinic acid, however, may also be observed as 

 such. 



The relation of oxalic acid to the ureids has already been con- 

 sidered. They are represented by the formulse : 



Oxalic acid (COOH) 2 = C 2 H 2 O 4 



Succinic acid (CH 2 ) 2 .(COOH) 2 = C 4 H 6 O 4 



Glutaric acid (CH 2 ) 3 . (COOH) 2 = C 5 H 8 O 4 



On oxidation they are decomposed into water and carbon dioxide, 

 but it is probable that during this transformation fatty acids are 

 formed as intermediary products : 



C 2 H 2 O 4 = CO 2 + H.COOH. 



C 4 H 6 4 = C0 2 + C 3 H 6 2 

 Propionic 

 acid. 



The principal aromatic oxy-acids which may be found in the 

 animal body are hydroparacumaric acid or para-oxy-phenyl-pro- 

 pionic acid, para-oxy-phenyl-acetic acid, para-oxy-phenyl-lactic 

 acid or oxy-hydroparacumaric acid, and para-oxy-phenyl-glycolic 

 acid. They are derivatives of phenol, in which one hydrogen atom 

 has been replaced by the radicle of the corresponding non-aromatic 

 acid, as shown by the equation : 



/OH 



C 6 H 3 .OH + CH 3 .CH.OH.COOH + O = C 6 H 4 < + H 2 O 



Phenol. Sarcolactic acid. \CH 2 .CH CH.COOH 



Para-oxy-phenyl- 

 lactic acid. 



