136 LABORATORY METHODS OF 



For microscopic examination it is best to have the 

 urine as fresh as possible. In the summer time it is 

 best to add to each four ounces of urine 10 grains of 

 sodium salicylate to prevent decomposition. 



The physical properties of the urine are too well 

 known to require special mention here. (See Physi- 

 ology oh the following points: color, odor, transpar- 

 ency, reaction and amount. ) The color is straw ; the 

 reaction is acid; the odor is peculiar to itself; the 

 amount ranges from 1000 c.c. to 1500 c.c. ; normal 

 urine is transparent. In disease all of this is changed, 

 each change representing a pathological process. 

 Sometimes several properties are changed in one case. 

 (For diseases represented by the changes, see Prac- 

 tice.) The method of making the physical analysis is 

 simple. Use the senses given you. For reaction 

 use litmus paper. Specific gravity of the urine is de- 

 termined by using the urinometer. The normal grav- 

 ity is 1 020 to 1025. 

 Method : 



1. Fill the cylinder of the urinometer two-thirds. 



2. Set it on a level table, and introduce the bulb of 

 the instrument in the center of the cylinder; when the 

 bulb comes to rest, read off the graduate on the stem of 

 the bulb. In case you have not enough urine to find 

 the gravity, you must add water enough to float the 

 bulb ; then multiply the gravity of the mixture by the 



