92 THE CLEAVAGE-PRODUCTS OF THE ALBUMINS. 



resents a most important constituent of many of the vegetable and 

 animal fats. On heating with hydriotic 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 n H 2n _ 2 O 4 . They include oxalic acid, succinic acid, and 

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

 form of their amides, viz., as aspartic acid and glutaminic acid, respec- 

 tively. 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 formulae : 



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



Succinic acid (CH 2 ) 2 .(COOH) 2 == C 4 H fi 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 4 = C0 2 + H.COOH. 



C 4 HA = C0 2 + C 3 H,0 2 

 Propionic 

 acid. 



The principal hydroxylated aromatic oxy-acids which may be 

 found in the animal body are hydroparacumaric acid or para-oxy- 

 phenyl-propionic acid, para-oxy-phenyl-acetic acid, para-oxy-phe- 

 nyl-lactic acid or oxy-hydroparacumaric acid, and para-oxy-phe- 

 nyl-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 hydrogen atom has been replaced by the radicle of the corresponding 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 5 .OH + CH 3 .CH.OH.COOH + O = C 6 H 4 < + H 2 O 



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



Para-oxy-phenyl- 

 lactic acid. 



They are probably all derivatives of tyrosin, and it has already 

 been shown how hydroparacumaric acid results from this on reduc- 

 tion, and is then transformed into para-oxy-phenyl-acetic acid by 

 oxidation. 



The formulae of these acids and their relation to tyrosin are as 

 follows : 



