I 
OF CORNWALL. 33 
fame colour and fubftance with the calcarious incruftations of the 
well. I therefore in the next place pulveriz’d fome of the incruft- 
ations brought from the well : Upon burning them over the fire 
they did not melt ; had no particular tafte or fmell : Upon throw- 
ing fome of the powder into the fire, concluding that if there 
were any fulphur in it the flame would have turn’d blue, it had no 
vifible efled: : I put a red-hot iron to it, but it fent forth neither 
fmoke nor fcent. Upon the whole, this water appeared fimple 
and unimpregnated ; nothing but the earth which forms the cal- 
carious coverings of the roof and floor of the cave appearing in it. 
But when I fay there is no fteel, no alum, no acid falts or fulphur, 
I would not be thought peremptorily to aflert, that there is nothing 
of that kind ; I mean only, that there is not any one of thefe vifibly 
predominant ; for Nature mixes and qualifies her ingredients inimi- 
tably and inimitably. We may pofiitively affirm, that fuch and 
fuch ingredients are to be found unqueftionably in Waters ; but 
others may be alfo there in a quantity to us indifcoverable ; and 
therefore we cannot abfolutely affirm, that in any Water there is 
no fuch fait, fteel, fulphur, or the like. 
In Cornwall there is a great number of thofe Waters, which, SECT IX _ 
from their principal ingredient, are called Chalybeate. The ftrongeft Of Mineral 
Water of this kind, and moft remarkable for its cures, which I have Waters ‘ 
heard of, or had the opportunity of examining, is that which rifes 
in the tenement of Colurian in the Parifh of Ludgvan. The bed 
through which this Water flows, is a loofe pebbly ground, mixed with 
a gravelly clay, full of the ochrous iron mineral, from which the 
tafte and fmell of the Water proceeds. Upon trying it feveral times 
with galls, it turned a deep reddilh purple ; with green tea, a lighter 
purple; with oak leaves, a blue-black of a purple caft. Upon 
pouring two thimbles full of fpirit of vitriol into half a pint, it made 
but a fmall effervefcence. I let the Water with the galls only ftand 
for fome time, and it retained its purple and tranfparency ; whereas, 
if it had turned black and turbid, as fome Waters do b , that would 
have been a difadvantageous fymptom. Upon dropping gently a 
large thimble full of fyrup of violets, about three fourths of an inch 
of the Mineral Water, towards the top of the glafs, kept its ufual 
colour ; the middle part turned to a pale greenifh yellow, which 
reached to within half an inch of the bottom ; and the remainder 
was of a light purple : but upon ftirring it, after it had flood half 
an hour, the whole became a deep green. Upon dropping a thim- 
e of tartar, it fell immediately to the bottom of the 
b Shaw on Mineral and Iflington Waters, page 227. 
K 
glafs, 
