462 PHYSIOLOGICAL CHEMISTRY 



moved by Obermayer's test (see page 405). The chloroform should 

 then be discarded, the acid-urine mixture diluted with one-third its 

 volume of water, and the test applied as described above. The urine 

 of patients who have ingested santonin or rhubarb responds to the test. 

 The test will serve to detect fructose when present in a dilution 

 of i : 2000, i.e., 0.05 per cent. 



2. Resorcinol-Hydrochloric Acid Reaction (Seliwanoff). To 5 c.c. of Seliwa- 

 noff's reagent 1 in a test-tube add a few drops of the urine under examination 

 and heat the mixture to boiling. The presence of fructose is indicated by the 

 production of a red color and the separation of a red precipitate. The latter 

 may be dissolved in alcohol to which it will impart a striking red color. 



If the boiling be prolonged a similar reaction may be obtained with 

 urines containing glucose. This has been explained 2 in the case of 

 glucose as due to the transformation of the glucose into fructose by 

 the catalytic action of the hydrochloric acid. The precautions neces- 

 sary for a positive test for fructose are as follows : The concentration of 

 the hydrochloric acid must not be more than 12 per cent. The reac- 

 tion (red color) and the precipitate must be observed after not more than 

 20-30 seconds of boiling. Glucose must not be present in amounts 

 exceeding 2 per cent. The precipitate must be soluble in alcohol with 

 a bright red color. 



3. Phenylhydrazine Test. Make the test according to directions under Glu- 

 cose, 3, page 22. 



4. Polariscopic Examination. A simple polariscopic examination, when taken 

 in connection with other ordinary tests, will furnish the requisite data regarding 

 the presence of fructose, provided fructose is not accompanied by other levorotatory 

 substances, such as conjugate glycuronates and /3-hydroxybutyric acid. 



ARSENIC 



When any soluble form of arsenic is introduced into the body in 

 any way, it is quickly absorbed and distributed by the blood and 

 lymph. The absorption is influenced by the quantity and quality of 

 the food in the stomach, and the activity of the circulation of the part 

 in contact with the poison. Some of the absorbed arsenic may be 

 returned to the alimentary canal by way of the bile and gastro-intes- 

 tinal mucous membrane. After absorption it may be deposited in the 

 liver, kidneys, brain, bone, muscles, and walls of the stomach and 

 intestines. It is eliminated in all of the excretions, but chiefly by the 

 kidneys and through the feces. It does not appear very promptly in 



1 Seliwanoff 's reagent may be prepared by dissolving 0.05 gram of resorcinol in 100 c.c. 

 of dilute (i : 2) hydrochloric acid. 



* Koenigsfeld: Bioch. Zeit., 38, 311, igi2. 



