Professor Dana on Morbid Animal Products: 149 
Arr. XTI.—Chemical Examination of some Morbid Ani- 
mal Products : by James Freeman Dana, M.D. Pro- 
fessor of Chemistry, &c. in Dartmouth College. 
Iv the spring of 1820 I had an opportunity of analysing_ 
the extensive collection of Urinary and other calculi belong- 
ing to the Anatomical Museum of Harvard College ; this 
collection was presented to the College by the late Dr. 
Nicuots of London, and for the privilege of examining it, 
I am indebted to the politeness of the Professor of Anatomy 
in that College, Dr. J. C. Warren, of Boston. 
The examination of these Calculi was commenced with a 
view to ascertain the relative numbers of the different spe- 
cies in this collection, but it became very interesting in its 
progress, as I found calculi which contained Urate of Am- | 
monia. Calculi containing urate of ammonia were noticed 
by Fourcroy and Vauquelin, but as this substance was not 
detected in the extensive examinations of calculi by Dr. 
Wortaston, or by Mr. Branope, it is well known that its 
existence as a component part of urimary concretions has 
been questioned, and it has been supposed that the French 
chemists were deceived by fallacious appearances. From 
the experiment of the British chemists, it cannot be inferred ’ 
that urate of ammonia never exists tn calculi, but that it is of 
very rare occurrence ; I am peculiarly fortunate in having 
had an opportunity to examine some calculi of which it isa 
component part. 
The existence of ammonia in calculi is acknowledged by 
Mr. Branpe, and his experiments lead him to conclude 
that it was combined with muriatic acid ; I have not yet had 
an opportunity of seeing a detailed account of his experi- 
ments, but his great and deserved reputation as a chemist, 
has led me in common with others, to place great confidence 
in his results. When, therefore, I first detected ammonia in 
these calculi, no doubt was entertained that it was combin- 
ed with muriatic acid, and accordingly the appropriate tests 
for that substance were applied, but the appearances pre- 
sented were so different from those produced by muriatic 
actd, that I was led to a further examination, and found the 
acid to be wrte. 
