in the Museum of Si, Bartholomeia^s Hospital. 4 1 JJ 



in your pages? The entire collection consists of 129 speci- 

 mens, of which about one third were unexamined ; the com- 

 position of the others had been pointed out some few years ago 

 by Dr. Hue. It was however necessary to re-examine many 

 of these, as from their not having been divided their internal 

 structure had not been described. In this as in most other 

 collections chemical composition has been taken as the basis 

 of arrangement. This plan would be sufficiently simple and 

 accurate if calculi were always homogeneous, but as by far 

 the greater number consist of layers differing in composition, 

 some additional method is necessary. In the present instance 

 the alternating calculi have been classed according to the 

 number of layers which are present, and these are subdivided 

 with reference to the composition of the nucleus. I am aware 

 that many objections might be urged against this method, and 

 it would no doubt have been more scientific to have grouped 

 together all those in which the layers observe a similar order 

 of succession ; but it was found that such an arrangement 

 would have introduced so many subdivisions as completely to 

 destroy that simplicity which in a museum continually subject 

 to increase it was necessary to preserve. 



The following table exhibits the relative frequency of each 

 species, together with the order of succession of the' layers in 

 the alternating calculi. 



Uric acid, nearly pure 11. 



Urate of ammonia intimately mixed with variable ) 



proportions of oxalate of lime and the phosphates J 



Oxalate of lime nearly pure 8. 



Phosphate of lime 4t. 



Phosphate of ammonia and magnesia 1. 



Mixed phosphates 1 10. 



Ditto deposited on foreign bodies J 3. 



Cystic oxide 2. 



Alternating Calculi. 



Uric acid : Urate of ammonia 4. 



Oxalate of lime 3. 



Phosphates 6. 



Urate of ammonia : Uric acid 2. 



Oxalate of lime ... 7. 



Phosphates 13. 



Oxalate of lime : Uric acid 3. 



■ Urate of ammonia 1. 



• Phosphates ... 13. 



8. 



