URIC ACID. SS 



ing, was published by Wohler and Liebig,* These chemists have 

 thrown a new light upon the nature of uric acid, and on the im- 

 portant part which it acts in the animal economy. If the view 

 which they have taken prove correct, and it agrees better with 

 the phenomena than the old opinion, the statement of Dr Pear- 

 son, that uric acid is not entitled to be considered as a real acid, 

 will after all be the true one. Liebig and Wohler consider it 

 as a salt having urea for its base. The other, or acid constituent, 

 has never been obtained in a separate state, and perhaps is inca- 

 pable of existing except when united to a base. 



Uric acid exists in small quantity in human urine, and may 

 be obtained in crystals when that liquid is cautiously concentra- 

 ted. Many urinary calculi consist almost entirely of it. In 

 them, however, it is mixed with the colouring matter of urine, 

 with the mucus of the bladder, and with other substances. The 

 urine of birds, as was first shown by Dr "Wollaston, consists 

 chiefly of urate of ammonia. The excrements of serpents (void- 

 ed about once a month) consist almost entirely of the same sub- 

 stance. 



The easiest method of obtaining uric acid is to take the ex- 

 crements of serpents or of birds, which are solid, nearly white, 

 and consist of urate of ammonia, mixed with more or less of 

 animal matter. Dissolve this matter by means of heat in a ley 

 of caustic potash or soda, and evaporate the solution to a thick 

 magma. Spread this magma upon a fine cloth, and wash it cau- 

 tiously with hot water till the liquid passes off colourless ; then 

 subject it to strong pressure between folds of blotting-paper. 

 Dissolve it in boiling water, and precipitate the uric acid by 

 means of muriatic acid. Collect it on a filter, and wash it with 

 cold water till that liquid ceases to have any taste. 



Thus obtained, uric acid has a snow-white colour, and is usu- 

 ally in fine powder, though sometimes in very minute prismatic 

 crystals. It has been obtained in pretty large crystals by Bott- 

 ger. They were hydrated uric acid composed of one atom uric 

 acid, and four atoms water, f 



It is destitute of taste and smell. According to Dr Henry, it 

 dissolves, in about 1400 times its weight of boiling water, and the 



* Annalen der Pharmacie, xxvi. 241 ; or Ann, de Chim. et de Pbys. Ixviii. 

 225. 



f Ann. der Pharm. xxxii. 315. 



C 



