OF INDIGO IN HUMAN URINE. 
305 
from some other substance, as urine-pigment, capable of being transformed into blue 
indigo, it is not easy to determine. It is most likely, however, that the formation of 
white indigo in all instances precedes that of blue, but it is uncertain whether the 
white variety is voided with the urine, or whether it is formed from some substance 
contained in that fluid subsequent to its elimination. The fact, however, that blue 
iudigo is in some cases immediately developed on the addition of hydrochloric acid 
to recent urine, appears to show that white indigo is present in the urine when first 
voided. 
It is at all events certain that a very close relation exists between indigo, whether 
colourless or coloured, and two animal products, namely hsematin and urine-pigment; 
and there is much reason for believing that in many of the present cases the indigo 
was formed either from modified or altered hsematin or urine-pigment, since some of 
the analyses show that blue indigo was freely developed from the aqueous solution of 
the brown extractive, which itself was found so nearly to resemble hsematin in its 
chemical manifestations. The close relation which exists between hsematin and 
indigo is shown by the following elementary analysis of these substances : — 
Hsematin 
(Mulder*). 
White indigo 
(Crum). 
Blue indigo 
(CRUMf). 
Carbon 
Hydrogen 
Nitrogen 
Oxygen 
70-49 
5-76 
11-16 
12-59 
72-72 
4-54 
10-60 
12-12 
73-22 
2-92 
11-26 
12-60 
Or, if the relation be exhibited in another way, it will be seen that there is a differ- 
ence of only four atoms of carbon and four of hydrogen between the composition of 
three atoms of indigo and one of hsematin — 
1 Hsematin = C 44 H 22 N 3 Q 6 . 
3 Indigo = C 48 H 18 N 3 O 6 . 
Again, leucine is a common product of the decomposition of organic, or rather of 
albuminous matters, and it was thought that this body was present in the alcoholic 
extractive ; if so, the relation between hsematin and indigo is still more remarkable ; 
for, as suggested by my friend Dr. Letheby, to whom I am much indebted for the 
aid afforded in these analyses, one equivalent of hsematin and two of water contain 
the elements of two atoms of indigo and one of leucine. The relation stands thus : 
C. H. N. O. C. H. N. O. 
1 Hsematin . 44 22 3 6^ |*2 Indigo . 32 12 2 4 
2 Water . . 2 2 J j 1 Leucine . 12 12 1 4 
44 24 3 8 44 24 3 8 
It is therefore not difficult to imagine that a transmutation of hsematin into indigo 
may be effected under certain circumstances both within and without the system. 
* Joum. fur Prakt. Chem., bd. 28. s. 340. f Annals of Philosophy, 2nd ser. vol. lxxxii. 
2 R 
MDCCCLIV. 
