TENDENCY TO CALCULOUS DISEASES. 71 



Lithic acid, oxalate of lime, and mixed phosphates 1 



Lithate of ammonia, oxalate of lime, and mixed phosphates ... 3 



oxalate of lime, and lithic acid 8 



phosphate of lime, and lithate of ammonia 1 



lithic acid, and mixed phosphates 2 



Oxalate of lime, lithic acid, and lithate of ammonia 1 



lithic acid, and oxalate of lime 1 



lithic acid, and mixed phosphates 2 



Calculi consisting of four or more deposits. 



Lithate of ammonia, oxalate of lime, lithic acid, and mixed phosphates 1 



Oxalate of lime, lithic acid, oxalate of lime, and mixed phosphates . 1 

 Lithate of ammonia, oxalate of lime, phosphate of lime, oxalate of 



lime, and lithate of ammonia 1 



328 



In this table, it will be seen, that about one half of the specimens are com- 

 posed of one description of material only ; and that the remainder consist of 

 alternating layers, more or less numerous, of most of the substances of which 

 human urinary calculi are composed. — On each of these substances, I shall 

 make a few observations. 



Of lithic acid and lithate of ammonia. 



The distinction between these substances, though veiy generally recognized 

 abroad, does not appear to have been much attended to in this country, till it 

 was noticed by Dr. Prout, about nine years ago, in the Medico-Chirurgical 

 Transactions* ; and afterwards, by the same gentleman, in his important and 

 interesting work on Calculous Disorders. The existence of lithate of ammonia, 

 as a frequent component part of calculi, was distinctly pointed out, under the 

 name of urate of ammonia, by Messrs. Fourcroy and Vauquelin, in their 

 paper on Animal Concretions in the Annales des Chiinie for 1799-|-; but as 

 they very singularly omitted all notice of Dr. Wollaston's celebrated com- 

 munication on a similar subject, which appeared in the Philosophical Trans- 



* Vol. X. p. 389. f Tom. xxx. p. 57. 



