C 22 3 J 
XV. ^ Letter on the Differences in the Structure of Calculi , which 
arise from their being formed in different Parts of the urinary 
Passages ; and on the Effects that are produced upon them, by the 
internal Use of solvent Medicines, from Mr . William Brande 
to Everard Home, Esq. F. R. S . 
Read, May 19, 1808. 
Dear Sir, 
Having availed myself of the opportunity you procured for 
me, of making a chemical examination of the calculi con- 
tained in the Hunterian Museum, as well as those in your 
own collection, I herewith send you an account of what 
I have done. 
Should the observations appear to you to throw any new 
light upon the formation of calculi, I request that you will do 
me the honour of laying them before the Royal Society. 
The collection which I have examined, is not only uncom- 
monly large, but the greater part of the specimens have his- 
tories of the case annexed to them. 
This circumstance enabled me not only to ascertain the 
situations in which the calculi were found, but likewise many 
of the circumstances attendant on their formation. 
I have therefore endeavoured to form an arrangement 
upon these principles, with a view to render the subject more 
clear and perspicuous. 
