154 THE SECRETIONS: 



ture the phosphate of soda dissolves a larger amount of uric 

 acid and hippuric acid than at a lower temperature,- at 100 

 more than at 60. It is owing to this, that urine, upon re- 

 frigeration, sometimes deposits uric acid, or urate of soda in a 

 crystalline state, which, of course, can only take place by the 

 uric acid, at a lower temperature, restoring to the phosphoric 

 acid the soda or potash which, at a higher temperature, it had 

 withdrawn from it. At the common temperature phosphoric 

 acid decomposes urate of soda, whilst, at a higher temperature, 

 uric acid decomposes phosphate of soda. When urine, con- 

 taining uric acid and manifesting an acid reaction, forms no 

 sediment upon cooling, it shows that the amount of the phos- 

 phoric acid and that of the uric acid exactly balance each other 

 with regard to their affinity for soda. Had there been present 

 a larger proportion of uric acid, this would have separated upon 

 cooling ; whilst, on the other hand, the presence of a prepon- 

 derating proportion of phosphoric acid would likewise have 

 caused the precipitation of uric acid, because the affinity of the 

 former for soda would then exceed that of the latter. This 

 explains the circumstance that urine, in certain states, when, 

 from some cause or other, its amount of sulphuric, hippuric, or 

 other acid, becomes increased, precipitates a larger proportion 

 of uric acid than urine in its normal state. The solubility of 

 uric acid in urine must decrease in proportion as the amount 

 of the other acids present in the urine increases, because those 

 acids share the soda with the uric acid ; and, of course, the 

 larger the amount of soda which combines with these other 

 acids the less comes to the share of the uric acid, It is like- 

 wise owing to this, that uric acid is very frequently precipitated 

 from urine upon the addition of mineral or other acids, and 

 that urine of a turbid whey-like appearance, from the presence 

 of uric acid, frequently manifests a far more strongly acid re- 

 action than normal urine. 



" Now, bearing in mind that the use of alkaline citrate, of 

 neutral tartrate of potash, bi-tartrate of potash, acetates of 

 potash and soda, and tartarized soda, renders the urine alka- 

 line by creating in it an amount of carbonated alkali; and 

 that, likewise, after the eating of fruit, such as cherries, 

 strawberries, &c., the urine is of an alkaline nature, inasmuch 

 as these fruits contain alkalies combined with vegetable acids, 



