378 PHYSIOLOGICAL CHEMISTRY 



meal. The urine obtained 2-3 hours after a meal or later is ordinarily 

 free from turbidity. Permanently turbid urines ordinarily arise from 

 pathological conditions. 



Odor. The odor of normal urine is of a faint, aromatic type. The 

 bodies to which this odor is due are not well known, but it is claimed by 

 some investigators to be due, at least in part, to the presence of minute 

 amounts of certain volatile organic acids. Dehn and Hartman 1 have 

 recently succeeded in isolating from urine a neutral ill-smelling substance 

 which they call urinod. Its empirical formula is CeH 8 0. Urinod occurs 

 in urine to the extent of only 1-2 parts in 100,000 parts of urine. 

 When the urine undergoes decomposition, e.g., in alkaline fermentation, 

 a very unpleasant ammoniacal odor is evolved. All urines are subject 

 to such decomposition if allowed to stand for a sufficiently long time. 

 Under normal conditions the urine very often possesses a peculiar odor 

 due to the ingestion of some certain drug or vegetable. For instance, 

 cubebs, copaiba, myrtol, saffron, tolu, and turpentine each imparts a 

 somewhat specific odor to the urine. After the ingestion of asparagus, 

 the urine also possesses a typical odor due to the presence of methyl 

 mercaptan (CH 3 SH) which is formed in the intestine and eliminated 

 in the urine. 



Frequency of Urination. The frequency of urination varies greatly 

 in different individuals, but in general is dependent upon the amount of 

 fluid in the bladder. In pathological conditions an inflammatory affec- 

 tion of the urinary tract or any disturbance of the innervation of the 

 bladder will influence the frequency. Affections of the spinal cord 

 which lead to an increased irritability of the bladder or a weakening of 

 the sphincter, or any condition lowering the residual capacity of the 

 bladder, will result in increasing the frequency of urination. 



Reaction. The mixed 24-hour urinary excretion of a normal indi- 

 vidual ordinarily possesses an acid reaction to litmus. This acidity in 

 normal cases is represented on the average by a hydrogen ion concentra- 

 tion of 10 X io~~ 7 , although it may vary from 0.40 to 150 X io~ 7 . The 

 reaction of the urine represents an equilibrium between a large number 

 of acid and basic constituents, both organic and inorganic, which it con- 

 tains. Although organic acids and bases play a part in producing the 

 normal reaction, this reaction is probably, in the main, dependent upon 

 the relative amounts of the mono- and dibasic sodium and potassium 

 phosphates present. The monobasic sodium phosphate (NaH 2 P0 4 ) 

 is acid in reaction, while the dibasic phosphate (Na2HPC>4) is alkaline 

 in reaction. The excretion of acid or alkaline phosphate by the kidneys 

 is one of the factors in the regulation of the neutrality of the blood and of 



1 Dehn and Hartman: Jour. Am. Chem. Soc. 36, 2136, 1914, 



