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Home Extracts. 
On the Formation of Pearls in the Urinary Bladder of 
a Bullock. 
By ALFRED S. Taylor, F.B.S., Lecturer on Chemistry , tfc. in 
Guy s Hospital. 
I LATELY received from Mr. Image, of Bury St. Edmunds, 
several concretions which had been taken from the urinary bladder 
of a bullock. They were perfectly spherical, and varied in di¬ 
ameter from about the sixteenth to the eighth of an inch. They 
had a light yellowish colour, and some of them were strongly 
iridescent with a distinct pearly lustre. The largest, which was 
about the eighth of an inch in diameter, weighed only 0‘7 grain, 
but it was bulky compared with its weight. The mean specific 
gravity of four of the calculi was found to be 2. The surface had 
no appearance of roughness, or of a crystalline character: it was 
smooth and shining; and, from the examination of a fractured 
portion, it was found that the calculus was made up of ver}' thin 
concentric laminae, having the same pearly iridescent lustre. It 
was so hard as to require trituration in an agate-mortar, in order 
to reduce it to a fine powder. The first effect of pulverizing the 
calculus was to separate it into fine scales, having a strong nacreous 
lustre, and of a light golden yellow colour. There was no nucleus. 
A portion of the fine powder, which was of a brownish white 
colour, when heated on platina gave out the smell of burning 
animal matter, and a slight carbonaceous residue was left. When 
this was burnt off, a white alkaline ash was obtained, which was 
proved to be lime. Another portion of the powdered calculus was 
entirely dissolved by all acids with effervescence, and the solution 
was found to consist of a salt of lime, without any admixture of 
magnesia or phosphoric acid. There was no uric acid present. 
Hence the concretion was proved to be carbonate of lime arranged 
in spherical layers, and intermixed with a small portion of animal 
matter. 
Mr. Image informs me that no less than 150 of these calculi were 
taken from the bladder of the bullock. 
Urinary concretionsof carbonate of lime are very unusual in the 
human subject; they are, however, frequently met with in a 
rough and amorphous state in herbivorous animals. Dr. Bird is, 
so far as I can ascertain, the only writer who has pointed out the 
