Pe ware h TA¥— 
WATERS from ICELAND. 103 
TuHeEse phenomena appear to me to have proceeded from the 
very weak and flow action of the acid and alkali on one ano- 
ther, in confequence of the exceflively diluted ftate in which 
they were mixed together, the alkali at the fame time not being 
pure, but combined with the filiceous earth, a fubftance for 
which it has a confiderable attraGtion. I therefore fuppofed 
that when [added the {mall dofes of diluted acid, the acid par- 
ticles remained for fome time difperfed through the liquor, 
without joining the alkali, and the water contained, at the fame 
time, a filicated alkali, if I may fo call it, and an unfaturated 
acid ; but the colour of litmus being much more difpofed to 
be affected and changed by acids than alkalis, it became red, 
and retained this colour as long as any particles of the acid re- 
mained unfaturated. Thefe, however, after fome time, being 
all attracted and faturated by the alkali, the colour was again 
changed by the remaining unfaturated alkali. 
Ir may perhaps be fufpected, that a {mall quantity of fixed 
air, detached from the alkali, might be the caufe of this tem- 
porary red colour, and that the colour returned again to blue, 
when the fixed air evaporated from the water: And I know 
that a very fmall quantity of fixed air, contained in water, is 
fufficient to change the colour of litmus, and that a confiderable 
time is required for its evaporation from the water, fo that the 
litmus may recover its natural tint; but it is equally true, that 
the fixed air never requires fo long a time for its evaporation as 
- feveral weeks, and that it has not the power to redden litmus, 
when an alkali is prefent, except when the quantity of the al- 
kali is exceedingly fmall, and that of the fixed air incomparably 
more than fufficient for faturating the alkali. In the prefent 
cafe, the laft of thefe conditions never could take place, the 
quantity of acid added at once being far too fmall to detach 
enough of air, even although the alkali had been originally fa- 
turated with air, which.it certainly was not ; it appeared rather 
to be in a cauftic flate, or very nearly cauftic. This reafoning 
fuggefted 
