790 THE URINE. 



1032, and that of the fermented urine 1020, the urine contains twelve 

 grains of sugar to the fluid ounce. This test, although not accurate to the 

 smallest fraction of a grain, is clinically all that is needed for ordinary quan- 

 titative work. 



(f) Feliling's method is the most reliable for volumetric determination of 

 the amount of sugar. Fehling's solution contains in a volume of 1000 c. c. 

 the following: 30.639 grammes of cupric sulphate, 173 grammes of pure 

 crystalline tartrate of sodium and potassium, and 500 grammes of a solution 

 of caustic soda of specific gravity 1.12. Of this solution 10 c. c. are reduced 

 by 0.05 gramme of sugar. 



Microscopic Examination. The urine, in an amount of four 

 to six ounces, is left at rest for at least six hours still better for 

 twelve hours either in an ordinary bottle of white glass, or in a 

 funnel-shaped champagne-glass. The sediment formed at the 

 bottom of the vessel is the subject for microscopic analysis, after 

 the transparent portion has been carefully decanted. We trans- 

 fer a droplet to the slide by means of a camel-hair brush or a 

 pipette ; the former answers all purposes if it is cleansed thor- 

 oughly with water after each examination. To preserve urine,' 

 we use either simple glycerine mixed with the sediment, and left 

 at rest in a broad, open vessel until the surplus water has evap- 

 orated ; or a small amount of alcohol can be added before the 

 admixture of glycerine. Pus-corpuscles, epithelia, and casts are 

 best preserved by adding to the whole amount of urine a few 

 drops of chromic acid solution, enough to precipitate the albu- 

 men and the other constituents. After several weeks the liquid 

 may be decanted and a few drops of alcohol added to the sedi- 

 ment, to prevent the growth of mildew. 



Before entering the study of urine, the extraneous matters must 

 be well known. In Fig. 357 the most common are illustrated. 



Silk-fibers are homogeneous, moderately shining; their cut 

 ends are flattened by the blades of the scissors, and rendered 

 slightly jagged. If woven, the single fibers assume wavy or 

 spiral impressions from their neighbors, and under these con- 

 ditions are also flattened. 



Linen-fibers are composed of smaller fibrillae and show trans- 

 verse fractures or breaches, caused by the process of hatcheling. 

 The finest fibrillae are broken on 2 irregularly from the surface of 

 the main fiber. 



Cotton-fibers are flat, wavy, and twisted, and are more com- 

 pact along the edges than in the center ; the central portion may 

 show irregular breaches, or it may be absent if the compact 

 edges are pressed together. 



