on the Composition of Urinary Concretions. 3 g 
4. That the above animal oxide was not found in the urinary 
concretions, or any other concretions, of any animal but the 
human kind. 
5. That this animal oxide was found also in human arthritic 
calculi, but not in those of the teeth, stomach, intestines, lungs, 
brain, &c. 
P. S. I think proper to subjoin a few experiments, made 
after the preceding paper was written, which afford evidence 
of the truth of some of my conclusions, and enable us to ex- 
plain several properties of animal concretions. 
I. On an Urinary Concretion from a Dog. 
This calculus may be said to be a great curiosity, for it is 
probably the only specimen in London. I owe the opportu- 
nity of examining it to Mr. H. Leigh Thomas, who met with 
it in the course of his dissections ; and therefore we have 
unquestionable authority, that the concretion was really from 
the urinary bladder of a dog. It is worthy to be noticed, that 
the animal appeared to be in perfect health. 
This concretion is of an oval figure ; is three inches and 
three quarters in length, and three inches in breadth ; is white 
as chalk; its surface is rough and uneven. Being sawed 
through longitudinally, no nucleus was found, nor was it lami- 
nated, but near the centre it was radiated, and contained shi- 
ning spicula. In other parts it was, for the most part, compact 
and uniform in its texture. It weighed nearly ten ounces and // * . 
a half. Its specific gravity was found to be greater than that of 
human urinary concretions, in general ; which I have learned 
by experiments is also the case with urinary and intestinal 
< 2 ? t if a ) 
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