APPENDIX 461 



culation of the percentage of sugar in the original sample of urine is very simple. 

 The 25 c.c. of copper solution are reduced by exactly 50 mg. of glucose. Therefore 

 the volume run out of the burette to effect the reduction contained 50 mg. of the 

 sugar. When the urine is diluted i :io, as in the usual titration of diabetic urines, 

 the formula for calculating the per cent, of sugar is the following: 

 0.050 

 .-- times 1000 equals per cent, in original sample,wherein X is the number of 



cubic centimeters of the diluted urine required to reduce 25 c.c. of the copper 

 solution. 



In the use of this method chloroform must not be present during the titration. 

 If used as a preservative in the urine it may be removed by boiling a sample for a 

 few minutes, and then diluting to its original volume. 



This solution will keep indefinitely and it is claimed by Benedict, that compari- 

 son with the polariscope and by Allihn's gravimetric process will show it to be more 

 accurate than any of the ordinarily used methods. 



APPROXIMATE QUANTITATIVE ESTIMATION with Fehling's solution. (One c.c. of 

 Fehling's solution is reduced by 5 mg. glucose.) 



Measure off 2 c.c. of Fehling's solution in a pipette and put in a test-tube or 

 small beaker and dilute with 20 c.c. of water. 



Bring the diluted Fehling's to boiling and drop in drop by drop the urine from 

 a dropping-bottle for which the number of drops per cubic centimeter has been 

 noted. Estimating 20 drops to the cubic centimeter if 2 drops of urine are re- 

 quired to reduce the copper it would show a sugar percentage of the urine of 10. 

 Four drops 5%, 8 drops 2.5%, 16 drops 1.25%, 32 drops 0.6%, 64 drops 0.3%, 100 

 drops 0.2%. 



Nylander's Bismuth Reduction Test. Put 5 c.c. of urine in a test tube and add 

 0.5 c.c. Nylander's reagent, then heat for five minutes in a boiling water bath. If 

 sugar be present the mixture will darken to become black on standing. For the 

 reagent digest 2 grams of bismuth subnitrate and 4 grams Rochelle salts in 100 c.c. 

 of 10% KOH solution. Cool and filter. 



Urinary Tests in Connection with Acidosis 



The determination of the ammonia quotient, which is the ratio of N eliminated 

 as ammonia to total nitrogen elimination, has assumed great importance by reason 

 of its connection with various forms of acid intoxication, as in diabetes, pernicious 

 vomiting of pregnancy, and various hepatic diseases. 



The degree of acidosis is better determined by the quantitative estimation of 

 nitrogen elimination as ammonia than by estimating quantitatively the amount of 

 diacetic and /3-oxybutric acid in the urine. Normally we have about 0.7 gram of 

 ammonia eliminated daily. In acidosis this may rise to 5 or 10 grams and instead 

 of being from 3 to 5% of the total N, it may amount to 30 to 50%. 



In the acidosis connected with chronic nephritis it has been found that the pre- 

 formed ammonia is often below normal, indicating a defect in the normal neutraliz- 

 ing action of ammonia. Where there is excessive formation of acid bodies as in 

 diabetes, or when liver cell degeneration interferes with the normal conversion of 

 ammonia into urea we have an increase in urinary ammonia output. 



