3 96 PHYSIOLOGICAL CHEMISTRY 



water (i : 1800) and practically insoluble in cold water (i : 39,480, at 

 i8C.). It is soluble in alkalis, alkali carbonates, boiling glycerol, 

 concentrated sulphuric acid, and in certain organic bases such as ethyl- 

 amine and piperidine. It is claimed that the uric acid is held in solu- 

 tion in the urine by the urea and disodium hydrogen phosphate present. 

 Uric acid possesses the power of reducing cupric hydroxide in alkaline 

 solution and may thus lead to an erroneous conclusion in testing for 

 sugar in the urine by means of Fehling's or Trommer's test. A white 

 precipitate of cuprous urate is formed if only a small amount of cupric 

 hydroxide is present, but if enough of the copper salt is present the 

 characteristic red or brownish-red precipitate of cuprous oxide is ob- 

 tained. Uric acid does not possess the power of reducing bismuth in 

 alkaline solution and therefore does not interfere in testing for sugar in 

 the urine by means of Boettger's or Nylander's tests. 



In addition to being an important urinary constituent uric acid 

 is present in small amounts in normal human blood as well as in the 

 blood of birds. It is also normally present in the brain, heart, liver, 

 lungs, pancreas, and spleen. 



Pathologically, the excretion of uric acid is subject to wide varia- 

 tions, but the experimental findings are rather contradictory. It may be 

 stated with certainty, however, that in leukemia, because of the destruc- 

 tion of nuclein material, the uric acid output is increased absolutely as 

 well as relatively to the urea output; under these conditions the ratio 

 between the uric acid and urea may be as low as i : 9, whereas the normal 

 ratio, as we have seen, is i : 50 or higher. An actual output of 12 grams 

 of uric acid per day has been reported in leukemia. In the study of the 

 influence of X-ray on metabolism Edsall and others have reached some 

 interesting conclusions. Edsall found that the excretion of uric acid is 

 usually increased and that in some conditions, particularly in leukemia, 

 it may be greatly increased. The excretion of total nitrogen, phos- 

 phates, and other sustances may also be considerably increased. 



In gout the kidney is said to lose the power of properly eliminating 

 uric acid and it collects in the blood in abnormally high concentration. 



Normal = 2-3 mg. uric acid per 100 grams of blood. 

 Gout = 4-10 mg. uric acid per 100 grams of blood. 



In gout the uric acid content of the urine is generally low preceding 

 an attack and increases during the attack. Atophan has been found 

 to increase the uric acid output in gout, apparently due to increased 

 kidney activity. 



The uric acid conterit of the urine is of importance in relation to the 

 formation of urjc acid calculi. The administration of alkali carbonates 



