256 
UIU NARY DEPOSITS. 
specimen of urine obtained from one of his patients. His 
first care will be to ascertain the reaction by his test-papers, 
then to nearly fill the graduated glass belonging to his 
urinometer, and insert the small thermometer. If the fluid 
has been recently collected, it may require the glass to be 
allowed to stand for a few moments in cold water, so as to 
reduce it to the required 60°; or if it has fallen below that 
temperature, a few passings of the spirit-lamp outside the 
glass, or the immersion of it in hot water will effect the de- 
sired elevation. The specific gravity being taken, the opera- 
tor next places a small quantity in a test-tube, and causes it 
to boil by the aid of the spirit-lamp. A greater or less 
amount of precipitate takes place, which may be merely a 
lime salt, or possibly albumen. To decide this a few drops 
of nitric acid are added. Should the precipitate increase, the 
evidence of albumen is pretty clear. On the other hand, if it 
becomes dissolved, it is merely a salt of lime thrown down, 
as salts of lime always are from the heated fluid. Another 
portion of the urine is to be acidulated by dilute nitric acid, 
adding afterwards an excess of the acetate of potash, and 
allowing a single drop of the sesquichloride of iron to run 
down the side of the tube into the fluid : no precipitate 
shows the absence of phosphoric acid, and the phosphates 
generally. Another portion is to be acidulated by acetic acid, 
and tested by a solution of lime : no precipitate indicates 
the absence of oxalic acid and the oxalates. 
This examination is sufficiently extended for all cases 
where the urine presents no prominent modification of 
colour, or of specific gravity. Besides the constantly occur- 
ring carbonate of lime deposit, we occasionally meet with the 
oxalate of lime, phosphate of lime, and the ammonio-magne- 
sian or triple phosphate. That these are seen so seldom, is 
possibly due to the very few careful examinations of the 
secretion in our patients rather than to the rarity of their 
occurrence. 
Of the carbonate of lime deposit it is unnecessary to treat, 
excepting where it occurs in immense quantities, as it does 
not rank as a condition of disease, but on the contrary as a 
normal constituent of the urine. The oxalates and phos- 
phates, occurring in sufficient quantities to form an appreciable 
precipitate, are always to be considered as products of diseased 
action ; the former indicating mal-assimilation, and the latter 
derangement of the nervous system. In examining the urine 
suspected to contain either or both of these salts, the chemical 
tests before suggested may be of some assistance ; but to 
diagnose with certainty, the urine must be examined by 
