URINE 329 



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. 



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

 volume of a 24-hour sample. 



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

 absence of a sediment. 



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. 



28. 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 C.) 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. 



29. Gravimetrically. If a gravimetric determination is de- 

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

 small weighing bottle and weigh quantitatively. From a pipette 

 run into the weighing bottle 25 c.c. of distilled water at room 

 temperature, stopper the bottle, and weigh. 



Note : The pipette should be cleaned with cleaning fluid 

 and then thoroughly rinsed, first with tap water and then 

 once or twice with distilled water. If the liquid gathers 

 in drops on the inside of the pipette after its contents have 

 been allowed to flow out, the cleaning should be repeated. 

 On emptying a perfectly clean pipette or burette, the in- 

 strument should be so clean that no drops remain hanging 



