PROPERTIES OF THE TJRLNE. 187 



now little more than an historical interest. But this can 

 hardly be said of the analysis by Berzelius, made early in the 

 present century ; for even in recent authoritative works upon 

 physiology, these are quoted as the most elaborate and relia- 

 ble of the quantitative examinations of the renal excretion. 1 

 In treating of this subject, we propose to give simply the 

 chemistry of the urine as it is understood at the present day, 

 dwelling particularly upon its relations to the physiology of 

 nutrition and disassiinilation. In doing this it will be neces- 

 sary to consider carefully the quantity, specific gravity, re- 

 action, etc., of the urine, with the variations observed under 

 different physiological conditions. 



General Physical Properties of the Urine.- The color 

 of the urine is very variable within the limits of health, de- 

 pending chiefly upon the character of the food, the quantity 

 of drink, and the activity of the skin. As a rule, the color 

 is yellowish, or amber, with more or less of a reddish tint. 

 The fluid is perfectly transparent, free from viscidity, and 

 exhales, when first passed, a peculiar aromatic odor, which 

 is by no means disagreeable. Soon after the urine cools, it 

 loses this peculiar odor, and has the odor known as urinous. 

 This continues until the liquid begins to undergo decompo- 

 sition. The color and odor of the urine are usually modified 

 by the same physiological conditions. "When the fluid con- 

 tains a relatively large amount of solid matters, the color is 

 more intense, and the urinous odor more penetrating ; and 

 when its quantity is increased by an excess of water, with 

 the low specific gravity, the color is pale, and the odor faint. 

 The urine passed in the morning is usually more intense in 

 color than that passed during the day. 



acid and an equal weight of water. This produced at first violent effervescence, 

 and when cold, a large quantity of flat, shining crystals made their appearance. 

 These crystals were undoubtedly nitrate of urea (CRUICKSHANK, Experiments on 

 Urine and Sugar, in HOLLO, Cases of the Diabetes Mellitus, London, 1798, p. 441). 

 1 BERZELIUS, Suite du memoire sur la composition des fluides animaux. An- 

 nales de chimie, Paris, 1814, tome Ixxxix., p. 38. 



