and some other Animal Fluids. 
113 
general chemical habitudes, and it appears probable that it 
may prove more useful in the art of dyeing than has hitherto 
been imagined, since neither the alkalies nor the acids (with 
the exception of the nitric) have much tendency to alter its 
hue. The readiness too with which its stains are removed from 
substances to which no mordant has been applied, seem to 
render it peculiarly fit for the purposes of the calico-printer. 
I have not extended these experiments, nor have I had them 
repeated on a sufficient scale to enable me to draw more ge- 
neral conclusions respecting the possibility of applying them 
with advantage in the arts : this would have led me into too 
wide a field, and one not immediately connected with the ob- 
jects of this Society : the subject, however, appears important. 
It is not a little remarkable that blood is used by the Arme- 
nian dyers, together with madder, in the preparations of their 
finest and most durable reds,** and that it has even been found 
a necessary addition to insure the permanency of the colour.^ 
This fact alone may be regarded as demonstrating the non- 
existence of iron as the colouring principle of the blood, for 
the compounds of that metal convert the red madder to gray 
and black. 
Whilst engaged in examining the colouring matter of the 
blood, I received from Mr. William Money, house surgeon 
to the general hospital at Northampton, some menstruous dis- 
charge, collected from a woman with prolapsus uteri, and 
consequently perfectly free from admixture of other secre- 
tions. It had the properties of a very concentrated solution 
of the colouring matter of the blood in a diluted serum, and 
* Tooke’s Russian Empire, Vol. Ill, p.497. 
+ Ai kin’s Dictionary, Art. Dyeing, and Philos. Magazine, Vol. XVIII. 
MDCCCXII. O 
