406 URINE. 



of free acid in morbid urine, compared with the phosphate of soda, 

 that this mode of explanation is no longer applicable. The acid 

 reaction of the urine depends, therefore, in many cases, on the 

 presence of hippuric and lactic acid no less than on that of the 

 acid phosphate of soda. If, moreover, the latter substance alone 

 were present in the urine, the phosphates of lime and magnesia 

 could only be dissolved in it either as acid phosphates or by 

 means of another free acid. But if, in this calculation of the free 

 acid from the precipitated baryta salts, the earthy phosphates had 

 been included in the weighing, the result always remained the 

 same ; or, in other words, there was more free acid than could 

 be accounted for from all the acid phosphates of the urine. The 

 water-extract of the urine commonly exhibits an acid reaction, 

 notwithstanding repeated rinsing with alcohol, solely owing to 

 its contained acid earthy phosphates, which must be present 

 wherever lactic or hippuric acid constitutes the acidifying principle 

 of the urine. 



The spontaneous decomposition of the urine stands in the 

 closest relation to the formation of its sediments, and even to 

 the formation of the urinary concretions, as Scherer* has shown 

 by several beautiful observations. We will next direct our atten- 

 tion to the almost normal sediment of the urine, which, as we have 

 seen in vol. i., pp. 214 217, consists essentially of urate of soda, 

 and commonly occurs under very different physiological and patholo- 

 gical relations. This sediment is often formed as soon as the freshly 

 discharged urine cools, and hence we might be disposed to believe 

 that its occurrence indicated nothing more than such an increase of 

 the urate of soda that the latter could no longer be held in a state 

 of solution in the urine at the ordinary temperature. This view is 

 supported on the one hand by the fact, that such rapidly formed 

 sediments of urate of soda are often completely dissolved on the 

 addition of less concentrated urine, and on the other, by all 

 these sediments becoming again dissolved as soon as the urine is 

 heated to 50 or 60 C. But it hardly requires the aid of the 

 thermometer to trace the connexion between the fall of the tem- 

 perature and the deposition of a sediment, to convince ourselves 

 that, in most cases, the turbidity and the formation of a sediment in 

 the urine occur long after the temperature of the fluid has become 

 identical with that of the surrounding atmosphere ; thus a period 

 of eight, ten, twelve, or even twenty-four hours, often intervenes 



* Ann, d. Ch. u. Pharm, Bd. 42, S. 171, and Untersuch. z. Pathol. 

 1843, S. 117. 



