[ I2 7 ] 
duced in thefe waters was the precipitation of an 
ochrous earth, but without the lead: appearance of 
any green colour. As I looked upon this as a lead- 
ing experiment in the hiftory of vitriolic waters 5 as 
I had often tried it, and as often feen the green coa- 
gulum produced with the folution of the factitious 
vitriol, and never could obferve it produced in any 
of the above water j I began to fufpedt, that thefe 
waters were either not poifeffed of a vitriolic fait at 
all, or elfe, that it was in fome refpedts very different 
from the factitious vitriol. For thefe reafons, Dr. Horf- 
burgh’s experiment appeared very extraordinary ; tho’ 
at the fame time I was greatly pleafed, that I fhould 
have the opportunity of repeating it, and of obferving 
thofe phenomena in this ferrugineous water, which 
I had fought for in vain in feveral others. But when 
I came to make the trial, I was yet more furprifed, 
when I found it mifgive, and that the ol. tart. p. d. 
produced no green colour or coagulum in this mine- 
ral water, nor caufed any other alteration in it, than 
the feparation of a large quantity of ochrous earth 
of a yellow colour, exa&ly the fame with what I had 
obferved in the other fteel waters. This failure 
made me immediately conclude, that I had fome- 
how or other committed an error in the experiment : 
and tho’ I was pretty fure, that the mineral water,, 
which I had ufed in it, was quite frefh, yet I could 
not be fo pofitive as to the oil of tartar, which I 
fufpedted to have been long kept. Yet that this 
could have been the caufe of my being fo unfucceif- 
ful, I could fcarcely believe, tho’ indeed 1 could affign 
no other. I was forry, that I had not afterwards an 
opportunity of repeating this experiment with more 
accuracy,. 
