474 THE PHYSICAL CHARACTERS OF THE URINE. 



Urine in a state of ammoniacal fermentation exhibits the odor of ammonia. 

 Of substances taken by the mouth, turpentine gives rise to the odor of violets, 

 copaiba and cubebs to an aromatic odor, and asparagus to a disgusting odor due 

 to methylmercaptan. Valerian, garlic and castor yield up some of their odorous 

 constituents to the urine. 



The reaction of normal urine is acid from the presence of acid salts, 

 especially acid monosodium phosphate (PO 4 H 2 Na). The latter re- 

 sults from alkaline disodium phosphate (PO 4 HNa 2 ), uric acid, hippuric 

 acid, sulphuric acid and carbon dioxid each taking up one atom of so- 

 dium, so that the phosphoric acid must be displaced to form the acid 

 salt. After a meat-diet acid potassium phosphate especially causes the 

 acid reaction. That the urine contains no free acid is shown by the fact 

 that no precipitate takes place on addition of sodium hyposulphite. 



Night-urine exhibits the highest, morning-urine the lowest degree of acidity. 

 Sometimes the reaction of the morning- urine is alkaline. 



The acid reaction becomes increased after ingestion of acids, such as hydro- 

 chloric acid and phosphoric acid; as well as of ammonium-salts, which are trans- 

 formed in the body into nitric acid; after active muscular exercise; after a milk- 

 diet; and pathologically in the presence of hyperacidity of the gastric juice. 

 The absolute elimination of acid is increased by marked diuresis, while the relative 

 elimination is diminished. 



The acidity of the urine is lessened and its reaction may even be rendered 

 alkaline: (i) By the ingestion of caustic alkalies, alkaline carbonates, or alkaline 

 salts of the vegetable acids the last being oxidized in the body into alkaline 

 carbonates. (2) By the presence of calcium or magnesium carbonate. (3) By 

 admixture of blood or pus of alkaline reaction. (4) By drainage of the acid gastric 

 juice outside the body through a fistula; further, in from one to three hours 

 after digestion, in consequence of the formation of acid in the stomach. (5) By 

 the absorption of alkaline transudates, such as serum or blood. (6) In con- 

 sequence of profuse secretion of sweat and hot baths. If the surface of the 

 body is kept at a temperature of 31 C. and 30 per cent, of relative humidity, 

 alkaline urine will be excreted in the morning-hours, on account of the fixed 

 alkaline carbonates, while the evening-urine exhibits a strongly acid reaction. 

 (7) The urine has rarely been observed to be alkaline in anemic persons, from 

 deficiency of phosphoric and sulphuric acids. 



The reaction is tested by means of strips of violet litmus-paper, which become 

 red when dipped in acid urine and blue in alkaline urine. In order to determine 

 the degree of acidity of the urine it is necessary to learn the amount of sodium 

 hydroxid required to render exactly neutral the reaction of 100 cu. cm. of urine. 

 For this purpose a solution of sodium hydroxid is employed of which each cubic 

 centimeter contains 0.0031 gram of sodium; i cu. cm. of this solution neutralizes 

 exactly 0.0063 gram of oxalic acid. From a graduated buret (Fig. 145) the sodium- 

 solution is permitted to escape drop by drop into a beaker containing 100 cu. cm. 

 of urine, with constant stirring, until violet litmus-paper no longer becomes either 

 red or blue. The amount of sodium-solution in cubic centimeters is read from 

 the scale of the buret, and as each cubic centimeter corresponds to 0.0063 gram 

 of oxalic acid, the amount of oxalic acid that is the equivalent of the acid in the 

 100 cu. cm. of urine can be readily estimated. The degree of acidity of the urine 

 is therefore expressed in terms of the equivalent amount of oxalic acid that is 

 fully neutralized by the same amount of sodium hydrate. 



The urine of carnivora varies in color from pale to golden yellow. It has 

 a high specific gravity and exhibits a strongly acid reaction. The urine of 

 herbivora has an alkaline reaction and therefore exhibits precipitates of earthy 

 carbonates (so that it effervesces on addition of acid) and of earthy basic phos- 

 phates. In the state of hunger it acquires the character of the urine of carnivora, 

 as under these conditions the animal in a certain measure lives upon its own 

 tissues. 



