366 PHYSIOLOGICAL CHEMISTRY. 



the destruction of cell substance in the body leads as regularly 

 to uric acid as does that of muscle proteins to urea. The use 

 of rich protein foods does not necessarily occasion greater 

 elimination of uric acid. It is only when they contain appre- 

 ciable amounts of the nucleins that this is the case. In addi- 

 tion to these facts it has been found experimentally that the 

 oxidation of nucleins outside the body leads to the production 

 of uric acid in small amount. 



Uric acid may be obtained synthetically by combining urea 

 with glycocoll, and at a high temperature it may be decom- 

 posed with production of urea, ammonia, prussic acid and 

 other bodies, under different conditions. But little importance 

 is attached to these facts at the present time, but formerly they 

 were supposed to support the view that uric acid is a stage in 

 the urea formation through which all the katabolic nitrogen 

 should pass. Of greater interest is this fact that when uric 

 acid is introduced into the circulation of certain animals some 

 of it appears to be destroyed, and with the production of a little 

 urea. Such observations suggest that possibly a small part of 

 our urea may come from uric acid, but they have no bearing 

 on the proposition that the acid in turn has its origin in the 

 nucleins and not in the common proteins. 



According to the structural formula above given uric acid 

 appears to have four hydrogen atoms of equal value in the 

 formation of salts. But apparently only two classes of salts 

 may be formed : neutral salts, in which two hydrogens are 

 replaced, and acid salts, in which but one hydrogen is replaced. 

 We have therefore salts of the types MC 5 H 3 N 4 O 3 and 

 M 2 C 5 H 2 N 4 O 3 . In addition to these, so-called quadriurates 

 are known as urine sediments. These salts are of the type 

 MC 5 H 3 N 4 O 3 * C 5 H 4 N 4 O 3 . The pure acid requires nearly 

 40,000 parts of water for solution; the neutral salts of the 

 alkali metals are much more soluble, while the acid salts are 

 but slightly soluble. The data given by different observers 

 are very contradictory. The salts of barium, strontium and 

 magnesium are nearly insoluble in water. 



