Chemical Science. 371 



ing matter, acted on and dissolved with facility in alkali, and 

 extremely soluble also in acids at a boiling temperature : thus 

 muriatic acid, scarcely raised to the boiling point, on the 

 powder of uric acid calculi, becomes of a dark green 

 colour, and the powder remains of a pale tint. This being 

 converted into urate of potash, and the salt afterwards decom- 

 posed, a uric acid is obtained of extreme whiteness, and the 

 liquor is scarcely coloured. The uric acid obtained by the 

 common mode, which is always yellow, even after many 

 washings, becomes extremely white, if treated with boiling 

 muriatic acid. Absence of colour is certainly a character of 

 pure uric acid, and my father has found many calculi of a 

 perfect whiteness, yet, nevertheless, rich in uric acid. {Litologia 

 Umajia.) 



Distilled vinegar becomes yellow when heated with the pow- 

 der of uric acid calculi. If an urate of lime be formed, and af- 

 terwards decomposed by distilled vinegar, a perfectly white 

 uric acid will be obtained. 



The other substance which accompanies uric acid may be 

 obtained by saturating the acid muriate of potash, left in the pre- 

 paration of uric acid, with the sub-carbonate of potash. The 

 green colour becomes of a dirty yellow, and, by degrees, a 

 turbidness takes place, which, after some time, gives rise to 

 extremely white flocculi. The uric acid, which has been ob- 

 tained, appears also to be contaminated with this matter, as 

 may be proved, if boiled in an acid, and the acid saturated with 

 potash. The substance seems to adhere very strongly to uric 

 acid, and can scarcely have its last portions separated. 



Acids, by their direct action on the powder of uric acid 

 calculi, when aided by heat, extract also a portion of this 

 flocculent matter; but it is separated in much greater quantity, 

 when the action of potash precedes. Indeed, if the calculi in 

 powder be treated with boiling acid, until no further portion of 

 the flocculent matter can be separated, and then converted into 

 urate of potash, this urate, decomposed by muriatic acid, 

 gives an acid muriate of potash, whidi, when saturated, preci- 

 pitates the white flocculi. 



