URINE 



513 



This procedure is described under 

 A modification of this method by Hunter 



10,6 

 10,4 

 10,2 

 10.0 



IB 



0.218 



0.221 

 0.225 

 0.228 

 .0.231 



Now wash, in turn, with alcohol and with ether and finally dry the paper and crys- 

 tals to constant weight at noC. In the process of washing the uric acid free from 

 chlorides an error is introduced, since every cubic centimeter of 

 water so used dissolves 0.00004 gram of uric acid. 1 For this rea- 

 son a correction is necessary. It has been suggested that the pig- 

 ment of the crystals is equivalent in weight to the amount of uric 

 acid dissolved by the first 30 c.c. of water, and this factor should be 

 taken into account in the computation of the percentage of uric 

 acid. 



Calculation. Since 100 c.c. of urine was used the corrected 

 weight of the uric acid crystals, in grams, will express the percentage 

 of uric acid present. 



5. Kriiger-Schmidt Method. Kriiger and Schmidt have de- 

 vised a method for the combined determination of uric acid and 

 the other purine bodies of urine. 



Purine Bases, below, 

 is also given. 



6. Ruhemann's Uricometer Method. Principle. When iodine 

 solution is added to urine an amount of iodine is absorbed roughly 

 proportional to the amount of the uric acid present. A special grad- 

 uated tube is required and carbon disulphide is used to indicate the 

 presence of excess iodine. 



Procedure. Fill the tube (see Fig. 165) to the lowest mark S 

 with carbon disulphide (the bottom of the meniscus should rest 

 on the line). Then add iodine solution (1.5 grams iodine, 1.5 

 grams potassium iodide, 15 grams absolute alcohol, and 185 grams 

 distilled water) to the mark J. Add urine to mark 2.45 (2.6 c.c.). 

 Insert the glass stopper and shake. The carbon disulphide will 

 show the dark brown color of iodine. Add more urine gradually 

 with continued shaking until only a violet-pink color remains in the 

 disulphide after shaking. Then add drop by drop with vigorous 

 shaking until the disulphide becomes colorless. Read on the scale 

 the amount of uric acid in parts per thousand of urine. 



When the uric acid content of the urine is low this method 

 gives reasonably accurate results from the clinical standpoint. 2 

 At a level of 0.3 gram per day the probable error will not exceed 

 10-15 per cent. Above i gram no limit can safely be placed on 

 the degree of error in pathological cases especially where albumin, 

 diacetic acid, purine bases and certain drugs are likely to be present. 

 The results by this method are ordinarily high. 



0.83 



