332 Mr Griffiths’s Experiments 
paper was instantly reddened, nearly as powerfully as if lime had 
been employed. 
This effect was considered as accidental, and as probably 
arising from some adventitious alkaline matter, or soap, adher- 
ing to the vessels employed. Another experiment was made, 
with greater care, in an agate-mortar, but with the same, or even 
a more decided result, in consequence of the more minute divi- 
sion of the material. When pulverized on perfectly clean and 
polished surfaces of iron, steel, zinc, copper, silver, and platinum, 
the effect took place, and apparently with equal facility ; but it 
was found that the presence of small quantities of oxide of iron 
greatly diminished it, in consequence, as was afterwards proved, 
of the particles of glass being by them defended from the con- 
tact of water. 
Since there are some saline bodies and metallic combinations 
which give indications of alkali to turmeric paper, although 
perfectly neutral compounds, and as pure magnesia reddens this 
paper when moistened with water, although no solution can be 
shewn to take place, possibly this might be an effect of the kind, 
it scarcely appearing probable that any soluble matter should be 
abstracted from the powdered glass by the mere affusion of pure 
water. Litmus paper, therefore, reddened by an acid, and paper 
stained with tfie blue infusion of ^abbage, were also employed 
as tests ; the former had its blue colour restored, and the latter 
was rendered green. 
A portion of flint-glass, in fine powder, was boiled in water 
for some hours ; upon being allowed to cool and subside, the 
clear portion was decanted and evaporated, and became strongly 
alkaline to the taste, and to other usual tests ; a drop of its con- 
centrated solution, gradually evaporated on a glass-plate, on ex- 
posure to the atmosphere, in a short time became deliquescent. 
Tartaric acid produced an effervescence, and afterwards a preci- 
pitate in this solution ; as likewise did muriate of platinum. 
From these experiments, therefore, it may be fairly inferred, 
that the alkali removed from the glass was potash in an uncom- 
bined state, and that the alkaline effect, combined in the first 
instance, did not depend upon the presence of any alkaline 
salts, or combination, adhering to or diffused throughout the 
glass. 
4 
