Memoir on Human Urine, Si 
increafes very fenfibly, and often very fpeedily. We bad no 
opportunity of determining the difference of the proportion 
in the urine of adults, or that of children, in which Scheele 
fays that it?s much more abundant. 
XII. The analyfis of urinary calculi, which firft directed 
our attention to urine as the fource of its concretions, jo- 
duced us to examine whether the oxalic acid exifted in this 
liquid. The oxalat of lime is, indeed, one of the mott fre- 
quent matters of calculi; and we have found it in the pro- 
portion of a fixth in the number of urinary {tones we exa- 
mined. None of the means which cam be employed to dif- 
cover the prefence of that acid, exhibited it to usin urine; 
while, on the other hand, the {fmalleft quantity of the oxalic 
acid, which we poured into the liquid, gave us an abundant 
and very heavy oxalat of lime; which proved to us, that fuch 
an acid could not remain diffolved in the urine. Thus, when 
a@ mural or mulberry-formed calculous, compofed of the 
oxalat of Jime.and an animal matter, by which it is agela- 
tinated,. arifes in the urinary duct, its production takes place 
even at the moment of the formation of the oxalic acid, 
This acid muft arife in the urine; and in that cafe there 
muft be in it an unnatural and morbific foreign production, 
There is reafon to believe that fome kinds of urine, which 
come from the body white and turbid, are charged with this 
falt; and that the oxalat of lime, formed by a caufe {tll un= 
known, iflues in this manner without producing calculi.” It) 
- may be thence feen of how much importance it is to make a 
chemical examination of the urine of difeafed perfons, and 
to eftablith a continued {eries of experiments on this fubject 
in fome hofpital fet apart for thefe ulcful refearches. 
The cafe is the fame with filiceous earth as with the oxalat 
of lime. We have never yet found it in urine, And its ex-. 
iftence in that liquid appears to be a rare cafe’ in pathology + 
of three hundred calculi, indeed, analyfed with care, two 
only were found centaining filex. . 
XIIJ.. This analyfis fhews that feveral matters, hitherto 
unknown in urine, exift in it, v2. 1, Phofpbat of magnefia, 
2. The urat of ammonia, which 1s formed at the time of the 
decompofition of the urine. 3. Albumen and gelatinous 
H 3 matter, 
