URINE. 313 



the urine with a small piece of compressed yeast. Transfer the 

 mixture to a saccharometer (Fig. 2, p. 31) and stand it aside in 

 a warm place for about 12 hours. If dextrose is present, alco- 

 holic fermentation will occur and carbon dioxide will collect as a 

 gas in the upper portion of the tube. On the completion of fer- 

 mentation introduce, by means of a bent pipette, a little KOH so- 

 lution into the graduated portion, place the thumb tightly over the 

 opening in the apparatus and invert the saccharometer. Explain 

 the result. 



5. Barfoed's Test. Place about 5 c.c. of Bar feed's solution 1 in 

 a test-tube and heat to boiling. Add the urine under examination 

 slowly, a few drops at a time, heating after each addition. Re- 

 duction is indicated by the production of a red precipitate. If the 

 precipitate does not form upon continued boiling allow the tube to 

 stand a few minutes and examine. NaCl interferes with this test 

 (Welker). 



Barfoed's test is not a specific test for dextrose as is frequently 

 stated, but simply serves to detect monosaccharides. Disaccharides 

 will also respond to the test, according to Hinkel and Sherman, if 

 the solution is boiled sufficiently long in contact with the reagent 

 to hydrolyse the disacchande through the action of the acetic acid 

 present in the Barfoed's solution. 



6. Polariscopic Examination. For directions as to the use of 

 the polariscope see page 32. 



PROTEINS. 



Normal urine contains a trace of protein material but the amount 

 present is so slight as to escape detection by any of the simple tests 

 in general use for the detection of protein urinary constituents. 

 The following are the more important forms of protein material 

 which have been detected in the urine under pathological conditions : 



1 I ) Serum albumin. 



(2) Serum globulin. 



I Deutero-proteose. 



(3) Proteoses J Hetero-proteose. 



[ " Bence- Jones' protein." 



(4) Peptone. 



(5) Nucleoprotein. 



(6) Fibrin. 



(7) Oxyhaemoglobin. 



1 Barfoed's solution is prepared as follows : Dissolve 4.5 grams of neutral, 

 crystallized cupric acetate in 100 c.c. of water and add 0.12 c.c. of 50 per cent 

 acetic acid. 



