432 



THE UEINE. 



food ; it is decreased after the ingestion of vegetable food, because 

 this contains compounds of organic acids which by oxidation form 

 carbonates, and these latter may be so plentiful as to make the 

 urine alkaline. 



The alkaline tide is a term applied to the condition in which 

 during the period when hydrochloric acid is being set free as a 

 constituent of the gastric juice the urine, through the elimination 

 from the blood of the bases, becomes less acid and sometimes even 

 alkaline. 



There is also a difference in the degree of acidity of the urine 

 at different times of the day, without regard to the food taken. 



Specific Gravity. This varies from 1015 to 1025, being 

 lower when the quantity of urine is increased, and higher when it 

 is diminished. It may, in extreme cases, as after the drinking of 

 large quantities of fluid, be as low as 1005. In diseased condi- 

 tions, as in diabetes mellitus, the quantity is greatly increased and 

 this is accompanied by a high specific gravity. 



Composition. In the following table are given two analyses 

 by Bunge of the twenty-four hours 7 mixed urine of a young man : 

 The "meat diet 77 consisted of beef with a little salt and spring- 

 water ; the " bread diet " consisted of bread, butter, and water : 



Total quantity in twenty-four hours 

 Urea . . . . 



Meat diet. 

 1672 c.c. 

 67.2 rams 



Creatinin ............. 2.163 



Uric acid ............ 1.398 



Sulphuric acid (total) ...... 4.674 



Phosphoric acid ......... 3.4/37 



Lime .............. 0.328 



Magnesia ............ 0.294 



Potash .............. 3.308 



Soda .............. 3.391 



Chlorin . . ........... 3.817 



Bread diet. 

 1920 c.c. 

 20.3 grams 



0.961 



9.253 



1.265 



1.658 



0.339 



0.139 



1.314 



3.923. 



4.996 



The urine of an adult living upon an ordinary mixed diet and 

 amounting in the twenty -four hours to 1500 c.c. would contain 

 approximately 1440 c.c. of water and 60 grams of solids, of 

 which 35 grams would be urea. 



Urea, CO(NH 2 ) 2 . Chemically this substance is an amid of 

 carbonic acid, and is also described under the name carbamid. It 

 is isomeric with ammonium cyanate, (NH 4 )CNO, and was pre- 

 pared therefrom by Wohler in 1828. It crystallizes in the form 

 of colorless needles or rhombic prisms ; is soluble in water and 

 alcohol, but is insoluble in ether and chloroform. 



With nitric acid, urea becomes urea nitrate, CO(NH 2 ) 2 NO 2 OH, 

 which forms in its crystallization rhombic tables; the angles of 

 these are usually cut off, making six-sided crystals, which fre- 

 quently overlap one another. The formation of these crystals is 

 used as a test for urea. 



