34 Observations on the Changes which take ‘place 
has not too much alkali, has a sweetish taste, and tinges yellow 
either blue or white paper. Acetic acid produces in it a light 
gelatinous precipitate, analogous in appearance to uric acid when 
obtained by a similar process. The substance precipitated has 
a yellow colour more or less deep; it does not readily crystallize 
like uric acid, but. presents here and there some shining points, 
and in drying it contracts and breaks in many pieces. It scarcely 
alters the blue tincture of vegetables, and destroys the colour 
previous to reddening it. In cold water it is almost insoluble. 
Lime and ammonia dissolve it; but the addition of an acid to the 
solution precipitates it again, although of a less deep colour. 
_ Henee these combinations, like the urats, are always dissolved in 
an excess of base. The combination with potash produces yel- 
low coagulations in the solutions of silver and lead. The above- 
mentioned substance which the acids precipitate burns with al] 
the characters of animal matter. Nitric acid projected on it is 
decomposed, and when the solution is evaporated no red colour 
appears; but, on the contrary, a residuum of a yellowish colour is 
found. Hence therefore results a substance in many characters 
analogous to uric acid, but which in many other essential qua- 
lities is distinct from it. To this substance is also united that 
particular yellow matter which we have seen accompanying the 
supposed lactic acid. In decomposing with acetic acid its com- 
bination with potash, the acetate of potash which passes. the 
filter is coloured yellow. By removing this salt, and evaporating 
the residue, we obtain matter equal to that which was produced 
by washing the original brown mass, if the acid combined with 
the ammonia which it contains be removed. This peculiar yel- 
low matter is soluble in water and in alcohol, but in a much 
greater degree when hot than cold. By evaporating it slowly it 
Maintains its colour, and is reduced to a mass having a gummy 
appearance, which seems disposed to crystallize and readily at- 
tracts humidity. - But if it is evaporated more rapidly, placing it 
in a watch- glass over the flame of a lamp, and removed from 
the heat when it has acquired much consistence, it appears 
chiefly remote from the centre where it attains the colour and 
appearance of wax. If the heat be continued it burns, emitting 
the smell of animal matter; it swells extremely on being con- 
verted into charcoal, and finally, with a slight crack the whole 
is destroyed in an instant. Nitric acid poured on it rapidly de- 
composes, and the solution after some time yields a white gra- 
nular depasit; evaporated, it entirely changes into a white mass 
at first sufficiently hard, but afterwards attracts humidity, when 
it is very difficult to reduce it to charcoal by heat. It would 
be difficult to determine the precise moment when each of the 
above-mentioned atibstances begins to be formed; and we can only 
form 
