URINE. 287 



acid in 100 c.c. of water rendered alkaline with potassium hydrox- 

 ide. Cool and carefully add 3 grams of potassium permanganate. 

 Filter, immediately acidulate the filtrate with acetic acid and allow 

 it to stand in a cool place over night. Filter off the crystals and 

 wash them with water. Save the wash water and filtrate, unite 

 them and after concentrating to a small volume stand away for 

 crystallization. Now combine all the crystals and recrystallize them 

 from hot water. Use these crystals in the experiments which 

 follow. 



3. Microscopical Examination. Examine the crystals made 

 in the last experiment and compare them with those shown in Fig. 

 93, page 286. 



4. Solubility. Test the solubility of allantoin in the ordinary 

 solvents (page 23). 



5. Reaction. Dissolve a crystal in water and test the reaction 

 to litmus. 



6. Furfurol Test. Place a few crystals of allantoin on a test- 

 tablet or in a porcelain dish and add 1-2 drops of a concentrated 

 aqueous solution of furfurol and 1-2 drops of concentrated hydro- 

 chloric acid. Observe the formation of a yellow color which turns 

 to a light purple if allowed to stand. This test is given by urea 

 but not by uric acid. 



7. Murexide Test. Try this test according to the directions 

 given on page 274. Note that allantoin fails to respond. 



8. Reduction of Fehling's Solution. Make this test in the 

 usual way (see p. 27) except that the boiling must be prolonged 

 and excessive. Ultimately the allantoin will reduce the solution. 

 Compare with the result on uric acid, page 275. 



AROMATIC OXYACIDS. 



Two of the most important of the oxyacids are paraoxy-phenyl- 

 acctic acid, 



CH 2 -COOH, 



OH 



and parao.r \phenyl-propionic acid, 



CH 2 -CH 2 -COOH. 



OH 



