URINE. 221 



The urine of a man of about 30 years of age, who was re- 

 covering from an attack of pleuropneumonia, and whose renal 

 secretion had always previously been rather dark-coloured, be- 

 came lighter and neutral. It was found one morning of a citron 

 colour, and had deposited a white crystalline sediment, which, 

 when observed under the microscope, was found to consist of 

 beautifully-formed crystals of ammoniaco-magnesian phosphate, 

 recognizable even by the naked eye, perfectly free from any 

 mixture with phosphate of lime, urates, or mucus. The urine, 

 which was filtered off, had a slight alkaline reaction, but did not 

 become turbid on heating : the addition, however, of any acid, 

 even acetic, produced a copious white turbidity, which did not 

 disappear on the addition of an excess of the acid, but slowly 

 vanished on the application of heat. In the acid urine thus 

 cleared by heat ferrocyanide of potassium produced no effect. 

 On evaporating the urine a sediment was deposited, and on 

 mixing the residue with alcohol, a large quantity of a white 

 substance was precipitated, which did not dissolve in water, and 

 consisted of phosphate of magnesia, urate of ammonia, and a 

 little extractive matter. Since the precipitate induced by the 

 addition of acids to the urine gradually crystallized, and ex- 

 hibited all the properties of uric acid, it is clear that the turbidity 

 and precipitate had been caused by the decomposition of an 

 urate which must have been present in a state of solution, to a 

 very large amount. The urine had a specific gravity of 1022. 



1000 parts were composed of: 



In 100 parts of 

 Analysis 102. of solid residue. 



Water .... 951-10 



Solid constituents . . . 48-90 



Urea . . . 20-80 42-0 



Uric acid 1 . . . 1'48 3'0 



Extractive matters . . 13-50 



Ammoniaco-magnesian phosphate and"! iQ-20 



other fixed salts . . J 



On the following day the properties of the urine were en- 

 tirely changed. The colour certainly was the same, but it no 

 longer had an alkaline reaction, nor did it form a crystalline 

 sediment, nor was any turbidity induced by the addition of an 

 acid. Free ammonia alone produced a slight cloudiness. 

 In a case of peripneumonia that recently occurred inSchonlein's 



1 The uric acid existed in the urine as urate of ammonia. 



