3 8 Dr. Pearson’s Experiments and Observations 
in the space of a few minutes, in most cases, and in all in a 
very little time, without any other apparatus than nitric acid, 
a round bottomed matrass or glass dish, and a lamp. By this 
method, I have, in a general way, examined above 300 speci- 
mens of concretions, of the human subject and other animals, 
principally urinary ones ; and also many from other parts, par- 
ticularly those from the joints. For these opportunities I am 
beholden to several professional gentlemen ; whose willingness 
to furnish me with specimens, I shall have much satisfaction in 
acknowledging on a future occasion. At present, I must ac- 
knowledge my obligations to Mr. Heaviside, in whose museum 
I found between 700 and 800 specimens. The liberal possessor 
of this treasure offered me, what I could not have taken the 
liberty of requesting, namely, permission to break off pieces 
from any of the articles, for experiment. Mr. Edward Howard 
did me the honour to take upon himself the task of writing 
down the reports, and otherwise assisted me. 
At this time I shall only mention, 
1. That out of 200 specimens of urinary calculi, not more 
than six did not contain the animal oxide above described, i. e. 
about 32 out of 33 contained it. 
2. That the proportion of this oxide was very different; va- 
rying from (exclusive of water,) to —§•§•; but, for the most 
part, varying between and * 
3. That the common animal mucilage of urine is frequently 
found in concretions, in very different proportions ; but is per- 
haps never a principal constituent part of them. 
* In some urinary concretions, the interior part contained this oxide, and the exteiior 
part had none of it. On the contrary, in other urinary concretions, the exterior part 
contained it, and the interior part did not. 
