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Uric Acid, sometimes called litliic acid, is, next to urea, 

 the most important nitrogenous constituent of the urine of man. 

 It has been said to be absent in herbivorous urine, being replaced 

 by hippuric. This has been shown by later researches not to be 

 strictly true, as a trace of uric acid is found in addition to the 

 hippuric. In birds and reptiles uric acid is the chief nitrogenous 

 constituent, being present in greater amount than urea. 



In man the proportion of urea to uric acid is about 45 to 

 ^1, ab^t 0.-5 gr^niaf the latter being excreted in i^e 24 hours. 



e^usei'.the .OTi(5k r^^. deposit- ■sx)meti'ines §^n -^n^'Tirine after ■: 

 Standing for a time. Its solubility.is very low, only 1 part bein^ 

 V 'soluble in. 14000 cc. of.-fcdld wat% and Ito ^^^SQOQ'Vin boiling.: v.. 

 Physiologically, it is increased and diminished pVoportionfrgl;^*' 

 . with urea. -Pathologically, it, is^' increased in^ indigestion; acuteC>^ 

 dropsies, rheumatic and' catarrhal inflamrftcations ; aftfer attackg'-' v'W4.- 

 of gout ; cancer of the liver ; in leucemia ; in a}l disturbances of 

 the circulation and respfiifatidn.' Pathologically uric acid is de- 

 creased in chronic diseases generally ; diabetes and polyuria ; be- 

 fore paroxysms of gout ; anemias ; chronic rheumatism ; chronic 

 diseases of spinal cord. 



Uric acid is generally in solution in the form of urates of 

 sodium, potassium, ammonium, lime and magnesium. These salts 

 are very easily decomposed even by weak organic acids. 

 Perform the following tests upon both urines (filtered). 



In a conical glass, add 5 parts of hydrochloric acid 

 to 30 parts of urine. Label and put in a cool place for 

 24 hours. Eed or brownish colored crystals of uric acid 

 are deposited upon the sides of the glass, or form a 

 pellicle on the surface of the fluid like fine grains of 

 cayenne pepper. The brownish-red color is due to pig- 

 ment (uroerythrin). 



Murexide Test. To about 1 cc. of human urine add 

 a little nitric acid; evaporate in a porcelain dish very 

 carefully to avoid charring. Cool and add a drop of 

 ammonia, a purple red color of murexide or purpurate 

 of ammonia is formed. It turns bluer upon the addition 

 of caustic potash solution. 



Dissolve a few crystals of uric acid in 10% caustic 

 soda or potash. Add a drop or two of Fehling's Solu- 



