i ?4 On the Differenced in the Structure of Calculi. 



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

 their texture, and entirely soluble in muriatic acid. 

 The composition 1 of the first was as follows : 



Grains. 



Phosphate of lime - - 65' 



Ammoniaco-magnesian phosphate 28* 



Loss - - *■ • 7* 



100- 



Of the second ; 



Phosphate or" lime - - 45; 



Ammoniaco-magnesian phosphate 38" 



Oxalate of lime - l%* 



Lossr = 5' 



100-* 



The deposition of calculous matter upon the bougie was 

 covered with blood, and in very small quantity, the bougie 

 having been removed by an operation soon after it had 

 passed into the bladder. It appeared to consist chiefly of 

 phosphate of lime. 



The incrustation upon the hazel nut was also destitute of 

 uric acid. 



Section IV. 

 Of Calculi of the Urethra. 



All those that were examined had escaped from the bladdef 

 while very small, and had afterwards lodged in the membra- 

 nous part of the urethra, where they had increased in size, 

 and formed a cavity in which they were more orless embedded. 



Two of these calculi were broken. 



The fragments consisted, in one instance, of ammoniaco- 

 magnesian phosphate, and phosphate of lime, with a smalf 

 portion of uric acid : and in the other the fragments were 

 composed entirely of the ammoniaco-magnesian phosphate. 



The third calculus was of a very remarkable appearance 5 

 its form being that of a perfect sphere, about half an inch in. 

 diameter. It was coated with small but very regular crystals 

 of die triple phosphate in its purest state. On account of the 



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

 the formation of oxalate of lime. 



singularity 



