LABORATORY EXERCISES. 467 



collected amount of twenty-four hours in all the quantitative work 

 on the urine which is to follow) (page 233). 



2. Estimate the phosphates : (a) total ; (6) the earthy ; and (c) the 

 alkaline (page 233). 



3. Estimate : (a) the total sulphates ; (6) the conjugate sulphates ; 

 (c) the neutral sulphur (pages 234, 235, and 290). 



Exercise XXVIII. 1. Prepare some urea from the urine (page 

 243) ; examine with a microscope the urea nitrate which is formed. 



2. Dissolve a few crystals of urea in 1 c.c. of water and add a 

 small amount of a strong solution of oxalic acid ; urea oxalate is 

 precipitated ; examine with a microscope. 



3. Heat some urea in a test-tube as described on page 242 ; note 

 the formation of biuret (page 36). 



4. Estimate the urea with sodium hypobromite solution, using 

 Doremus' ureometer ; the gas evolved is nitrogen ; the CO 2 which 

 is formed is taken up by the excess of sodium hydrate in the hypo- 

 bromite solution (page 243). 



5. Estimate the urea according to Folin's method (page 244). 

 Exercise XXIX. Determine the total amount of nitrogen in the 



urine according to Kjeldahl's method (page 245). 



Exercise XXX. Isolate some uric acid from human urine 

 (page 251). 



2. Note the insolubility in water. 



3. Perform the murexid test, the copper test, Dennige's test, and 

 Schiff's test (page 250). 



4. Estimate the uric acid according to Folin's method (page 251). 

 Exercise XXXI. 1. Estimate the oxalic acid according to Dun- 

 lop's method (page 255). 



2. Isolate kreatinin as kreatinin-zinc chloride (page 259). 



Exercise XXXII. 1. Test the urine for indican, using Jaffe's 

 test or Obermeyer's test (page 265). 



2. Estimate the indican according to Wang's method (page 266). 



Exercise XXXIII. Feed a dog a couple of grammes of chloral 

 and demonstrate glucuronates in the urine the next day (page 270). 



Exercise XXXIV. Prepare artificial diabetic urine, containing 

 /3-oxybutyric acid, diacetic acid, acetone, and glucose ; let stand for 

 several hours. 



1. Polarize the urine and note the degree of dextro rotation. 



2. Ferment the urine with yeast for twenty-four hours and re- 

 examine (Isevorotation due to oxybutyric acid). 



3. Estimate the oxybutyric acid as a a-crotonic acid (page 281). 



4. Test for diacetic acid, using both Arnold's and Gerhardt's test 

 (pages 281 and 282). 



5. Test for acetone in the distillate (see page 282) ; use Legal's, 

 Lieben's, and Gunning's tests (page 282). 



6. Estimate the acetone (page 284). 



Exercise XXXV. 1. Prepare some cystin from human hair as 

 described on page 290. 



