Royal Microscopical Society. 
Ill 
6. Pure urate of soda and pure uric acid were added in equal 
quantities to a weak non-gelatinizing solution of gelatin. Mixture 
boiled and filtered. In the filtrate there appeared at the end of 
twenty-four hours (temp. 45°) forms as in No. 4. At the end of 
forty-eight hours, the temperature having meanwhile fallen to 
40°, the spheres were found covered with a dense deposit of needles 
(Fig. 6). The precipitate included three groups of forms : a, large 
irregular masses, looking like black velvet ; h, dark brown spheres, 
with a halo of densely-packed fine bristles ; c, curious pale spheres, 
looking very much like pus-globules in partial decomposition. They 
were composed of a thin crust of tiny radiating rods and a cavity 
within containing a few granules not having any obvious regularity 
of arrangement. All these forms were imbedded in a gelatinous 
matrix distinctly defined from the original solution. This matrix 
may have been hardened gelatin, or a compound of urate or uric 
acid and gelatin, or a colloidal form of uric acid or urate. And the 
deposit of needles may have been either a further crystallization or 
a metamorphosis. The fact that where they could be seen the 
spheres round which the bristles were arranged were imperfect on 
one side and reduced to crescents is important. See Fig. 6, h. 
7. The whole mixture of No. 6 was boiled for some time, but 
without perfect solution of the precipitate. It was filtered, and the 
solution was divided into two equal portions, a and h. 
To a, a solution of 20 grains of chloride of sodium in half an 
ounce of distilled water was added. The next day (temp. 45°) 
there was a brownish granular deposit resolved under high powers 
of the microscope (300 diam.) into fine matted needles and mole- 
cular matter. To fc, acetic acid in excess was added. Kesult, next 
day (temp. 45°), long slender wheatsheaves ; circular radiant 
tufts of needles ; large, very perfect rhombohedra ; and very large 
foliaceous and pennate crystals. 
8. To fresh urate, of alkaline reaction, uric acid added in de- 
cided excess. This, after boiling in distilled water and filtering, 
deposited at 45° dense tufts of needles. The solution was only 
faintly acid. 
9. Neutral urate of soda with equal quantity of uric acid boiled 
in distilled water. Solution acid. Filtrate deposited delicate navi- 
cular crystals, single, in bunches and in stars. 
10. To boiling solution of urate of soda with slight excess of 
uric acid an equal quantity of boiling distilled water added. Solution 
cooled by next day to 38°. A small deposit, chiefly on the surface, 
of thick navicular crystals with central hollow ; no other forms. 
11. Mixture in 10 boiled, evaporated to ^, and then divided 
into two portions ; one rendered alkaline by four drops of liq. sodae, 
the other left acid. Cooled to 38°. The first day produced soft 
much conglobate spheres, in semi-gelatinous matrix, in both solu- 
VOL. XIII. K 
