URINARY DEPOSITS. 
257 
the microscope. For this purpose the fluid, being slightly- 
warmed, is placed under the quarter-inch power, and the 
oxalates will be discerned by the octohedrai or dumb-bell 
form of crystals ; and the phosphates by the prismatic or 
stellated ones. 
The inorganic deposits are by no means the only ones oc- 
curring in the urine ; indeed it seems that matters derived 
from the animal tissue are even more frequent, such as albumen, 
blood, pus, and bile. Of the first named, I have not met 
with an instance where it has not been mixed with some of 
the other constituents of the blood. Its presence is easily 
ascertained by the emphtyment of nitric acid as a test, furnish- 
ing a white precipitate. The application of heat having the 
same effect, the double test is necessary : neither by itself 
being considered satisfactory. In the event of blood being 
present, the tests for albumen will develope the characteristic 
reaction, while the colour of the urine leads us to conclude 
the nature of the deposit. To make the matter certain, 
ParirePs test is a simple and effective one. The suspected 
urine is to be boiled and filtered, to the brow r n precipitate on 
the filter add liquor potassae ; a greenish fluid passes through, 
to w hich add a few 7 drops of hydrochloric acid, w 7 hen a white 
precipitate immediately falls. If blood be present, all the re- 
actions will be quite defined : neither one is sufficient by 
itself. The urine in a case of red water would frequently, by 
its colour, lead us to infer the presence of blood, but the 
above test does not develope all the requisite reactions. The 
fluid deposits a brown sediment by boiling, and also by the 
addition of nitric acid, indicating the presence of albumen 
and some colouring matter; but as no green solution follows 
from the use of the liquor potassae, and no precipitate from the 
hydrochloric acid, it cannot therefore be considered that 
blood is present. 
The microscope furnishes a means of distinguishing be- 
tween the urine in a case of red-water, and some from a 
case of haematuria ; and at once proves the value of Pariret’s 
test. The blood-discs do not at all times appear as w r e see them 
w r hen examining a specimen of blood, namely, w 7 ith the external 
ring, and an inner darker portion, but simply as a series of 
rings. Apparently some of the water of the urine has, by ab- 
sorption, distended the investing membrane. This idea is 
strengthened hy observing, that after the specimen has be- 
come nearly dry on the object-glass, the central portion is 
quite apparent. 
In the specimens of red-water I have examined, nothing 
resembling a blood-disc could be discerned. Numerous 
xxvm. 33 
