having a Cinder as its Nucleus. 1 89 



lute acid and covered with a small bit of glass, was quickly in- 

 verted so as to stand upon the glass. In this way the bottle 

 soon became filled with gas, which, upon being transferred into 

 a small tube of lime-water and agitated in it, was quickly ab- 

 sorbed, rendering at the same time the lime-water milky. Hence 

 the earthy part of the calculus is chiefly composed of carbonate 

 of lime mixed with a little animal membrane. The exterior 

 surface of the calculus is of a brown colour, and presents that kind 

 of uneven appearance usually seen in mulberry calculi. The 

 brown coating, however, is quite superficial, and is probably de- 

 rived from animal matter, as T could find no trace of uric acid. 

 Curious as the structure of this specimen is, I regret that the 

 history of it is extremely obscure. It belongs to my friend Mr. 

 Richard Smith senior, surgeon to the Bristol Infirmary, whose 

 account of it I have transmitted to you. 



Any one from its figure and appearance might consider it as 

 a human calculus ; but it is hardly possible to conceive how a 

 cinder of this size could have been introduced into the bladder 

 either of a male or female: besides which, the non-existence of 

 uric acid which is generally present in some proportion or other in 

 human calculi, and the fact of its being composed of carbonate of 

 lime, — a very common ingredient in animal calculi, but a rare one 

 in those of the human bladder, — are considerations very contra- 

 dictory to this idea. May not the cinder have been wantonly 

 thrust into the bladder of a cow or some other animal, and iu 

 this way have given origin to the present concretion ? 



I recollect Mr. Brande, in a paper of his in the Philosophical 

 Transactions, speaks of several human urinary calculi having 

 extraneous bodies for their nuclei, one of which was an hazel 

 nut. 



Having had free access to the extensive collection of Mr. 

 Richard Smith, and having gone through the analysis of a va- 

 riety of specimens, I may here take an opportunity of stating 

 that I have met with three calculi, all human, which contained 

 a small admixture of carbonate of lime. In dissolving a calculus 

 (which I had reason to believe one of the ammoniaco-magnesian 

 phosphates) in acetic acid, I was surprised at .seeing a slow effer- 

 vescence take place, which I found by the expedient above de- 

 scribed to proceed from the disengagement of carbonic acid. 

 The proportion of carbonate of lime was discovered by dissolving 

 a few grains of it in dilute muriatic acid. To the solution pure 

 ammonia was added, which threw down the phosphates of lime, 

 ammonia and magnesia: these being separated, the solution was 

 treated with carbonate of potash, and in another experiment with 

 gxalate of ammonia, both of which gave a distinct precipitate. 



The 



