28 Dr. Pearson’s Experiments and Observations 
reasons mentioned in the last paragraph, it cannot be the 
same thing as the acid sublimate of Scheele, or the succinic 
acid. | 
4. As it does not appear to be putrescible, nor form a viscid 
solution with water, it cannot be referred to the animal muci- 
lages. 
5. On account of its manner of burning in the air, under 
the blowpipe, ( e , 6.) and its yielding, on exposure to fire in 
close vessels, the distinguishing products of animal matter, 
(especially ammoniac and prussic acid,) as well as on account 
of its affording a soap-like matter with caustic soda, this preci- 
pitate may be considered as a species of animal matter ; and, 
from its composition being analogous to that of the substances 
called, in the new system of chemistry, animal oxides , it belongs 
to that genus. Its peculiar and specific distinguishing properties 
are, imputrescibility, facility of crystallization, insolubility in cold 
water, and, that most remarkable property of all others, pro- 
ducing a pink or red matter, on evaporation of its solution in 
■nitric acid .* 
I do not avail myself of various other conclusions in this 
place, because they relate especially to the agency of medicines 
for preventing and removing concretions ; and of course do not 
properly fall within the views of the Royal Society. 
Having found the above precipitate to be an oxide, and not, 
as is commonly supposed, an acid, I thought it probable that, 
* It is much to be wished that we possessed equally delicate tests ©f the other species 
of animal matter, which are confounded together, although, from their obvious pro- 
perties, there is reason to believe they are of very different kinds, as is the case with 
the matter of the brain, liver, voluntary muscles, mucus, &c. Mr. Hunter has dis- 
covered a distinguishing specific property of pus, and one is here indicated for the 
oxide of urinary concretions. 
