333 
on the Action of Water upon Glass . 
The remaining sediment from the above solution, after having 
been repeatedly washed in successive portions of water, became 
inert as to its action on test papers, not affecting their colours in 
the slightest degree ; but, upon trituration , its alkaline power 
was again developed ; this property being evidently dependent 
upon the exposure of a new or undecomposed surface. A slight 
application of heat to the water was found greatly to facilitate 
this evolution of alkali. 
In order to determine the quantity of alkaline matter ab- 
stracted from a given weight of glass, by long and continued 
boiling, 100 grains of flint-glass, in fine powder, were boiled 
nearly every day for some weeks, in two or three successive por- 
tions of water; after this process, the insoluble residue was 
found deficient in weight by nearly seven grains. This result, 
however, must not be considered as accurate, but as a mere ap- 
proximation : for, on the one hand, small portions of glass might 
have been carried away in the supernatant liquor ; and, on the 
other, more alkali might have been abstracted by repeatedly tri- 
turating during the process, which, under these circumstances, 
would be almost unlimited. 
To some pure, dilute, muriatic acid was added very fine flint- 
glass, in powder, till it was completely neutralised by its alkaline 
effect. Upon being allowed to subside (which, however, was not 
very readily effected, minute particles remaining suspended for 
weeks together), the clear portion afforded a crystalline salt on 
evaporation, having the characters of muriate of potash. 
It may be remarked, that this solution, when perfectly clear, 
contained no lead, on testing for it by sulphuretted hydrogen; 
but upon agitating or diffusing the fine powder of glass through 
water, holding the gas in solution, it was immediately discoloured 
or blackened. 
Flint-glass, although chosen for the above experiments, is not 
the only variety possessing this remarkable property ; crown and 
plate glass, white enamel, and what is more remarkable, New- 
castle green-bottle glass, and tube of the same material (in the 
composition of which there is, comparatively, little alkali), also 
Reaumur’s porcelain, made from the green-bottle glass, possess 
the power of acting upon vegetable colours as alkalies. 
These experiments, tending to prove that glass is a body of 
VOL. XIV. m 82. APRIL 1826. Y 
