640 URINE. 



yellowish-brown, rose-colored, or often brick-red precipitate (sedimentum 

 lateritium) settles on cooling, because of the greater insolubility of the 

 urates at the ordinary temperature than at the temperature of the body. 

 This cloudiness disappears on gently warming. In new-born infants 

 the cloudiness of the urine during the first 4-5 days is due to epithelium, 

 mucus-corpuscles, uric acid, and urates. The urine of herbivora, which 

 is habitually neutral or alkaline in reaction, is very cloudy on account 

 of the carbonates of the alkaline earths present. Human urine may 

 sometimes be alkaline under physiological conditions. In this case it 

 is cloudy, due to the earthy phosphates, and this cloudiness does not 

 disappear on warming, differing in this respect from the sedimentum 

 lateritium. Urine has a salty and faintly bitter taste produced by sodium 

 chloride and urea. The odor of urine is peculiarly aromatic; t*he bodies 

 which produce this odor are unknown. 



The color of urine is normally pale yellow when the specific gravity 

 is. 1.020. The color otherwise depends on the concentration of the urine 

 and varies from pale straw-yellow, when the urine contains small amounts 

 of solids, to a dark reddish yellow or reddish brown in stronger con- 

 centration. As a rule the intensity of the color corresponds to the con- 

 centration, but under pathological conditions exceptions occur such as 

 are found in diabetic urine, which contains a large amount of solids and 

 has a high specific gravity and a pale-yellow color. 



The reaction of urine depends essentially upon the composition of the 

 food. The carnivora, as a rule, void an acid, the herbivora, a neutral 

 or alkaline urine. If a carnivore is put upon a vegetable diet, its urine 

 may become less acid or neutral, while the reverse occurs when an herbi- 

 vore is starved, that is, when it lives upon its own flesh, as then the urine 

 voided is acid. 



The urine of a healthy man on a mixed diet has an acid reaction, 

 and the sum of the acid equivalents is greater than the sum of the basic 

 equivalents. This depends upon the fact that in the physiological 

 combustion of neutral substances (proteins and others) within the 

 organism, acids are produced, chiefly sulphuric acid, but also phosphoric 

 and organic acids, such as hippuric, uric, and oxalic acids, aromatic 

 oxy acids, oxyproteic acids l and others. From this it follows that the 

 acid reaction is not due to one acid alone. The various acids take part 

 in the acid reaction in proportion to their dissociation, since, according 

 to the ion theory, the acid reaction of a mixture is dependent upon the 

 number of hydrogen ions present. Hence the theory that the acidity 

 is due entirely to dihydrogen phosphate is incorrect although this salt 

 takes such a great part in the acid reaction that its quantity is often 

 taken as a measure of the degree of acidity of the urine. 



1 See St. Kozlowski, Bull. Acad. d. scien. de Cracovie, Jan., 1909, 37. 



