R. H. Chittenden— Equine Caleult. 195 
Art. XXVIL—Contributions from the Sheffield Laboratory of 
Yale College. No. XXXVI.— On some interesting Equine 
Calcult; by R. H. CHITTENDEN, Ph.B., Assistant in Physio- 
logical Chemistry. 
closing up the passage completely. In the stomach was found 
another calculus of the same appearance, but a third larger. 
A year previous to this the animal was taken sick in the same 
manner, and as a result of treatment passed a calculus differing 
from the others only in size, being somewhat smaller. Through 
the kindness of Mr. Baldwin, I was able to obtain these calculi 
for examination. The following is the result: The smallest 
calculus was perfectly smooth, nearly round and of light-brown 
color, its nucleus was a small pebble around which the material 
was arranged in concentric layers, preserving the form of the 
nucleus. A short distance from the center was a small, loose, 
narrow ones of a darker shade; it was nearly round, its circum- 
ference one way being 114 inches, the other 114 inches, its weight 
was 679°6 grams, The calculus found in the intestine and which 
caused the death of the animal, weighed 441°57 grams; its nu- 
cleus was a thin and narrow piece of iron half an inch long. 
A transverse section revealed the same internal structure as the 
other, except that in this there was an extra spot of hair-like 
matter in the compact layer about the nucleus. The surface of 
the calculus, like that of the others, was perfectly smooth. On 
fracturing half of this ealeulus it separated readily into four 
distinct and regular layers, each of which was made up of smal- 
ler ones which could not be separated. On dissolving the sub- 
stance in cold dilute nitric acid, a pale yellow fluid was obtained 
and a residue made up of organic matter, with a little silica. 
Not a trace of urie acid was found in any of the layers. The 
first or outer layer was nearly ¢ of an inch thick; its specific 
gravity was 1°72. The second layer was ,% of an inch thick, 
with a specific gravity of 1°69. The third layer was } of an inch 
