70 CLINICAL MICROSCOPY AND DIAGNOSIS. 



phenyl-hydrazin. The tube is cooled by plunging into 

 cold water, and a microscopic examination made for 

 phenyl-glucosazone crystals. This is a delicate test. 



(d) Estimate the percentage of urea using Doremus' 

 or larger ureometers. 



These tests will be all that are usually called for in 

 routine clinical work. Quantitative estimates may be 

 required at times of uric acid, phosphates, chlorides, 

 or sulphates. For these, a work on urine analysis 

 should be consulted. 



3. Microscopic examination. 



Urine which is turbid, may be examined at once but 

 it is better to wait till a sediment has formed. This is 

 best effected by placing the urine in a conical glass and 

 allowing to settle from 3 to 24 hours. The supernatant 

 fluid is then decanted, and the sediment is placed with 

 a pipette upon a slide and examined under the low 

 power of the microscope. Care should be taken to 

 withdraw the lowest sediment with the pipette. A cen- 

 trifuge may be used for rapid sedimentation. 



Much can be learned of the nature of a sediment by 

 noting its color, general characters, the reaction of the 

 urine, and whether in urine at the time of passing from 

 bladder. The elements examined for microscopically 

 and which appear as a rule as sediments may be divided 

 into three classes, (1) chemical, (2) anatomical, (3) bac- 

 terial. 



1. The chemical sediments consist of various crystal- 

 line and amorphous chemical bodies which may exist 

 normally or be present abnormally in urine. We may 



