the Urine in Man and Carnivorous Animals. 475 



and this of course must give rise to the liberation of a certain 

 amount of phosphoric acid, or what comes to the same point, 

 to the formation of a certain amount of acid phosphates of 

 soda, lime, and magnesia. The proportional amount of the 

 liberated phosphoric acid varies with the temperature ; at a 

 higher temperature the phosphate of soda dissolves a larger 

 amount of uric acid and hippuric acid than at a lower tempe- 

 rature, — at from 37"-38° more than at 15°. It is owing to 

 this that urine, upon refrigeration, 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 a higher temperature it had withdrawn from it.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 com- 

 mon temperature phosphoric acid decomposes urate of soda, 

 whilst at a higher temperature uric acid decomposes phos- 

 phate of soda. When urine, containing uric acid and mani- 

 festing an acid reaction, forms no sediment upon cooling, it 

 shows that the amount of the phosphoric acid and that of the 

 uric acid exactly balance each other with regard to their affi- 

 nity 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 preponderating propor- 

 tion of phosphoric acid would likewise have caused the pre- 

 cipitation 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, be- 

 cause those acids share the soda with the uric acid ; and of 

 course the larger the amount of soda wiiich combines with 

 these other acids the less comes to the share of the uric acid. 

 It is likewise owing to this that uric acid very frequently pre- 

 cipitates 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 reaction than normal urine. 



Now, bearing in mind that the use of alkaline citrate (Gil- 

 bert Blane), of neutral paratartrate of potash, bi-tartrate of 

 potash, tartarized soda, acetates of potash and soda, and tar- 

 tarized borax, renders the urine alkaline 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 alka- 



