648 
EXCREMENTS OF MAN AND ANIMALS. 
port-wine-coloured solution, from which the margaric acid is 
deposited. On then adding water to the solution, and con- 
centrating it on the water-bath, a flaky-colouring matter 
separates, which, being purified by solution in ether, and 
washing with water, is obtained as a dark brown or black 
amorphous substance, similar to the colouring matter of 
blood, and to that which Dr. Harley has lately extracted, 
from urine. The matters brought down with the lime 
having been thus extracted, the sediment which spon- 
taneously subsides from the alcoholic solution of faeces 
before its treatment with the milk of lime is next ex- 
amined. This deposit appears to be complex in its nature ; 
it has a strongly acid reaction, and presents under the 
microscope small oily globules, mixed sometimes with crystals 
of excretine, and accompanied by a yellow amorphous matter. 
By boiling with alcohol and filtration, a residue remains, which 
the author has not yet examined, and two substances are 
obtained from the filtrate. The first is deposited on cooling ; 
when collected and dried on filtering paper it has a granular 
character, and is quite colourless ; it is very sparingly soluble 
in ether, fuses by heat, and burns with a bright fuliginous 
flame, leaving a white residue, consisting of phosphate of 
potash. The author has not yet been able satisfactorily to 
decide whether this is a pure immediate principle or not ; he 
is inclined to consider it as a combination of phosphate of 
potash and a pure organic substance. The filtered fluid, 
after separation of this matter, still contains a substance, 
which he has called excretoic acid. It is obtained by evapo- 
rating to dryness, extracting the residue with ether, adding 
to the ethereal solution alcohol and lime-w^ater, and heating. 
The acid is precipitated in combination with lime, from which 
it is separated by means of sulphuric or hydrochloric acid and 
solution in ether. The ethereal solution, after being well 
washed with w*ater to remove mineral acid, yields the pure 
excretoic acid on evaporation. This body is of an olive 
colour; it fuses between 25° and 26° C., and at a higher 
temperature burns without residue. It is insoluble in water 
and in a boiling solution of potash ; very soluble in ether ; 
sparingly soluble in cold alcohol, readily so in hot; its 
solutions having a marked acid reaction. The author is 
disposed to believe that in excrement it is combined in form 
of a salt, with excretine or a basic substance closely allied to 
it, w T hich is obtained in the filtrate from w T hich the excretoic 
acid is precipitated in combination with lime in the process 
of its purification. The author failed to obtain evidence of 
