URIC ACID. 203 



exhibit an alkaline reaction, and is precipitated by hydro-chlorate of 

 ammonia and the alkaline bicarbonates. 



Neutral urate of soda, NaO.C 5 HN 2 O 2 -f HO crystallises in wart- 

 like masses, dissolves in 80 or 90 parts of boiling water, is slightly 

 soluble in alcohol, and insoluble in ether; at 100 it loses its water 

 of crystallisation. 



Bi-urate of soda, NaO.C 5 HN 2 O 2 +HO.C 5 HN 2 O 2 + HO crys- 

 tallises in short hexagonal prisms, or in thick six-sided (microscopic) 

 tablets, which commonly arrange themselves in star-formed masses 

 in which the individual crystals are larger and can be more 

 distinctly made out than in the microscopic aggregations of the 

 ammonia-salt ; it begins to lose its water of crystallisation at 1 70, 

 and is soluble in 124 parts of boiling and 1150 parts of cold 

 water. 



Bi-urate of ammonia, H 4 NO.C 5 HN 2 O 2 + HO.C 5 HN 2 O 2 , may 

 be obtained crystallised in extremely delicate needles, but it also 

 forms under the microscope, globular opaque masses, from some 

 points of which extremely delicate spikelets may be seen to 

 project. 



Almost all the other salts of uric acid occur as amorphous 

 precipitates, and consist of 1 atom of base and 2 atoms of uric 

 acid, of which 1 atom always retains its basic atom of water; 

 hence we cannot well assume that the atomic weight of uric acid 

 should be doubled, (that is to say=C 10 H 2 N 4 O 4 ) for if, with such 

 an atomic weight, these salts were all neutral salts, they, or at all 

 events, some of them, would certainly lose this 1 atom of water at 

 a higher temperature. 



The salts of baryta, strontia, and lime, are represented by the 

 formula RO.C 5 HN 2 O 2 + HO.C 5 HN 2 O 2 + HO. 



Bi-urate of magnesia, MgO.C 5 HN 2 O 2 + HO.C 5 HN 2 O 2 + 6HO, 

 crystallises in delicate needles, loses 5 of its 6 atoms of water at 

 170 , and dissolves in 160 parts of boiling water, but in not less 

 than 3800 parts of cold water. 



Bi-urate of lead, PbO.C 5 HN 2 O 2 +HO.C 5 HN 2 O 2 +HO, is a 

 white powder, which loses its water of crystallisation at 160. 



Bi-urate of copper, CaO.C 5 HN 2 O 2 H-HO.C 5 HN 2 O 2 + 5HO, is 

 a green powder which, at 140, loses 3 atoms of water of crystal- 

 lisation. 



Sulphate of uric acid, HO.C 5 HN 2 O 2 + 4 (HO.SO 3 ), is formed 

 by dissolving uric acid in warm concentrated sulphuric acid, from 

 which, on cooling, it separates in colourless crystals, which fuse at 

 70, in cooling again solidify in a crystalline mass, and become 



