420 
DR. YELLOLY ON THE TENDENCY 
rature, and Art, for Oct. — Dec. 1829* ; and the correctness of that gentleman’s 
observations, receives a strong and important confirmation by the instance 
which I have brought forward ; though they might, at first view, be considered 
as liable to some doubt, both from the circumstance of the granules being 
uncombined, and from its being necessary to depend, to a certain extent, on 
the fidelity of the patient as to their source. 
Dr. Venables has kindly allowed me the inspection of his specimens, which 
bear some resemblance (though they are much more minute, and are of an 
amber tinge,) to those which I have mentioned as coming under my own view ; 
and he has stated in a letter to me, that in one instance, after carefully 
filtering and putting aside for a fortnight, a portion of the urine from which 
some of the granules mentioned by him had been derived, he found the 
inside of the glass studded, in two or three places, with minute crystals of 
silex, strongly resembling those which were thrown down by the urine. The 
precise modes in which silex is capable of being held in solution, have not all 
of them been distinctly ascertained; but this fact bears a considerable analogy 
to the deposition of regular crystals of rock crystal, from solutions of silex in 
fluoric acid, or in alkalis, after such solutions have been put aside for a consi- 
derable period. 
I have not much to add to the statistical observations which I made in my 
former communication. I may remark, however, that it appears, from infor- 
mation lately obtained by Mr. Copland Hutchison, that the calculations rela- 
tive to the tendency to calculous diseases in Scotland, in which I followed 
Mr. Smith of Bristol, have been a good deal under-rated ; and that the average 
disposition of that part of the kingdom to such complaints, differs but little 
from that of England in general'}-. 
There seems to be much of the same variation with regard to the prevalence 
of calculous diseases in Scotland, that there is in England ; some districts 
being exceedingly liable to these complaints, while others are very free from 
* New Series, No. XII. p. 234. 
t Further Inquiry into the comparative Infrequency of Calculous Diseases among Sea-faring 
People ; with some Observations on their Infrequency in Scotland. Medico-Chirurgical I ransactions, 
vol. xvi. p. 94. 
