42 °N THE STRUCTURE OF CALCULI. 



phosphate being situate «xternally, and in the greatest abun- 

 dance. 

 One of 23 02. The largest calculus, whiah I have seen, weighed, when 

 z6grs. recently removed from the bladder, twenty-three ounces 



and twenty-six grains. It consisted of a large mulberry or 

 oxalate of lime calculus, the nucleus of which was uric 

 acid, surrounded by a considerable quantity of the ammo* 

 niaco-magnesian phosphate in a very pure state. 

 Oneof J5|oz. Another very large calculus, weighing fifteen ounces and 

 a half, consisted of a nucleus of uric acid, enveloped in the 

 ammoniaco-magnesian phosphate, not however pure, but in- 

 tersected by several laminae of uric acid. 



Four distinct substances are extremely rare in calculi; I 



Four distinct have seen one in which the uric acid, the ammoniaco- mag- 



♦ubstances nesian phosphate, the phosphate of lime, and the oxalate of 



lime, were all in perfectly separate and distinct layers. 



Four calculi, having the following extraneous substances 



Four formed for their nuclei were examined. 



«wr foreign nu- \, A common garden pea. 

 cJei, 



2. A needle. 



3. A hazel nut. 



4. A part of a common bougie. 



In the two first instances, the calculous depositions were 

 of a pale gray colour, inclining to white; soft and friable in 

 their texture, and entirely soluble in muriatic acid. 



The composition of the first was as follows; 



Grs. 

 Phosphate of lime • 65 • 



Ammoniaco-magnesian phosphate* • 28* 



Loss • • • • • • • 7 # 



100- 

 Of the second ; 



Phosphate of lime » • * 45* 



Ammoniaeo-magnesian phosphate •• 38* 



Oxalate of lime ] £• 



Loss • • « 5* 



100 



* 



* It appears, that in this case there had been an accidental disposition 

 to the formation of oxalate of lime. 



The 



