URINE 95 



residue is treated with 3% H 2 S0 4 which dissolves the purine 

 bases and leaves the uric acid undissolved. The dissolved 

 purine bases may be reprecipitated with silver nitrate solution. 



X NH CO 



CREATININE, HN=C\ 



X N-CH 3 -CH 2 



Creatinine appears in the urine as the result of the inges- 

 tion of meat which contains creatine. The amount is also 

 somewhat dependent upon the nitrogenous metabolism, 

 being decreased in starvation. For the relationship be- 

 tween creatine and creatinine and the reactions and tests, 

 see under Muscle. On a mixed diet about 0.1 grm. is ex- 

 creted in 24 hours. 



Creatinine allows of a separation from the urine as 

 follows : 



To 50 c.c. of urine add 3 c.c. of a saturated solution of 

 sodium acetate and then 10 c.c. of a saturated solution of 

 HgCl 2 . Filter off the precipitated urates, sulphates, and 

 phosphates, and set the nitrate aside for 24 hours. The 

 mercury compound of creatinine separates out in the form 

 of spherical globules. Examine some under the microscope. 

 This compound of creatinine is readily decomposed by acids 

 or by H 2 S. Try Weyl's or Jaffe's test directly on the urine 

 and then on the creatinine isolated by the above method. 

 Test its reducing power. 



CONJUGATE SULPHATES. 



Of the toxic substances which are formed as the result of 

 intestinal putrefaction of the proteins, phenol, p-cresol, 

 indole, and skatole appear in the urine in the form of alkali 

 salts of non-toxic ethereal combinations with sulphuric 

 acid; pyrocatechinol and hydrochinol are also excreted in 

 the same way. Taken together these compounds are denoted 



