294 PHYSIOLOGICAL CHEMISTRY. 



in equal volumes and shake gently in a separatory funnel. Sepa- 

 rate the ether extract, evaporate it to dryness and dissolve the resi- 

 due in 2-3 c.c. of absolute alcohol. Note the greenish fluorescence. 

 Examine the solution spectroscopically and observe the characteristic 

 absorption-band (see Absorption Spectra, Plate II). 



6. Ring Test. Acidify 25 c.c. of urine with 2-3 drops of con- 

 centrated hydrochloric acid, add 5 c.c. of chloroform and shake the 

 mixture. Separate the chloroform, place it in a test-tube and add 

 carefully 3-5 c.c. of an alcoholic solution of zinc acetate. Observe 

 the formation of a green ring at the zone of contact of the two 

 fluids. If the tube is shaken a fluorescence may be observed. 



C. UROERYTHRIN. 



This pigment is frequently present in small amount in normal 

 urine. The red color of urinary sediments is due in great part to 

 the presence of uroerythrin. It is easily soluble in amyl alcohol, 

 slightly soluble in acetic ether, absolute alcohol or chloroform, and 

 nearly insoluble in water. Dilute solutions of uroerythrin are pink 

 in color while concentrated solutions are orange-red or bright red : 

 none of its solutions fluoresce. Uroerythrin is increased in amount 

 after strenuous physical exercise, digestive disturbances, fevers, cer- 

 tain liver disorders and in various other pathological conditions. 



PTOMAINES AND LEUCOMAINES. 



These toxic substances are said to be present in small amount in 

 normal urine. Very little is known, definitely, however, about 

 them. It is claimed that five different poisons may be detected in the 

 urine, and it is further stated that each of these substances pro- 

 duces a specific and definite symptom when injected intravenously 

 into a rabbit. The resulting symptoms are narcosis, salivation, 

 mydriasis, paralysis and convulsions. The day urine is principally 

 narcotic and is 2-4 times as toxic as the night urine which is chiefly 

 productive of convulsions. 



PURINE BASES. 



The purine bases found in human urine are adenine, carnine, 

 epiguanine, episarkine, guanine, xanthine, heteroxanthine, hypo- 

 xanthine, paraxanthine and i-methylxanthine. The main bulk of 

 the purine base content of the urine is made up of 'paraxanthine. 

 heteroxanthine and i -methyls anthine which are derived for the 

 most part from the caffeine, theobromine and theophylline of the 



