CHEMICAL BASIS OF THE ANIMAL BODY. 1259 



by the addition of acids to either solutions of the acid or to 

 urine. Hence it is extremely difficult to illustrate them within 

 reasonable limits, and for figures of the various possible forms 

 some special work must be consulted. The impure acid crys- 

 tallizes much more readily than does the purified. The follow- 

 ing figure shews additionally some very characteristic forms 

 in which uric acid separates out from urine either spontane- 

 ously or after the addition of hydrochloric acid. 



Fig. 212. Crystals of Uric Acid. (After Funke.) 



Uric acid is remarkably insoluble in water (1 in 14,000 or 

 15,000 of cold water, 1600 of boiling). Ether and alcohol do 

 not dissolve it appreciably. On the other hand, sulphuric acid 



Fig. 213. (Krukenberg after Kiihne.) 



Urinary sediment, showing chiefly the most usual form of crystals of acid 



sodium urate, C5H 3 NaN40 3 . 



takes it up in the cold without decomposition, and it is also 

 readily soluble in many salts of the alkalis, as in the caustic 



