URINE 279 



follows: On rising in the morning empty the bladder and dis- 

 card the urine voided. Then collect all urine voided during the 

 day, and the first voiding on rising the following morning. This 

 constitutes a complete 24-hour specimen. For the observations 

 in this section and the quantitative analysis in the section fol- 

 lowing, a complete 24-hour specimen should be used, and all 

 determinations made on the same specimen. 



As some urinary constituents decompose on standing, it is 

 necessary to add a preservative to the urine. In collecting a 24 

 hour sample, 5 c.c. of 5% thymol in chloroform should be placed 

 in the bottle intended for collection of the sample, before the 

 urine is collected. Neglect of this precaution may lead to loss 

 of the specimen through decomposition. 



a. Volume. Measure in a large cylinder and record the volume 

 of a 24-hour sample. 



b. Record the color, odor, transparency and presence or 

 absence of a sediment. 



c. Specific gravity. The specific gravity may be determined 

 either gravimetrically or volumetrically. For most clinical work, 

 the determination with an areometer or ' ' urinometer " is suffi- 

 ciently accurate. 



1. Volumetrically. Pour the urine into an areometer cylinder 

 and determine the specific gravity with an areometer which reg- 

 isters 1.000 to 1.060. Make sure that the instrument floats free 

 in the urine without touching the walls of the cylinder. As the 

 instruments are standardized for a definite temperature (usually 

 15 0.) it is necessary to correct for any variation in the tem- 

 perature of the urine from that indicated on the instrument. 

 For every 3 C. variation a correction of 0.001 is added or sub- 

 tracted from the reading, according as the urine is warmer or 

 colder than the standard temperature. Observe the temperature 

 of the urine and make any necessary correction as described 

 above. 



2. Gravimetrically. If a gravimetric determination is desired, 

 it may be made as follows: Carefully clean and dry a small 

 weighing bottle and weigh quantitatively. From a pipette run 



