ano: An ANALYSIS of 
‘been filtrated, without danger of feparating any part of the fi- 
liceous earth from the water by that operation. This is a con- 
fequence of the fingular nature of the filiceous earth, feveral 
properties of which, hitherto unnoticed, or not exactly defcribed, 
I became acquainted with in the courfe of thefe experiments. 
We have no experience of the poflibility of diflolving this 
earth in its concrete ftate by water alone ; but if it be diflolved 
in water by means of an alkaline falt, although we afterwards 
completely faturate the alkali with an acid, the earth thus fepa- 
rated, provided there is enough of water, will not fubfide ; it 
will remain diffolved ; the mixture will appear perfeCtly tranf- 
parent, and will pafs through the filtre without the fmalleft 
difficulty. To gr. 1000 of the Geyzer water, I added more than 
enough of acid to faturate the alkali. I then boiled the mix- 
ture a little while, until a fmall part of it only was evaporated, 
and I fet it afide in a quiet place. I know it contains a little 
more than half a grain of filiceous earth; but after ftanding 
twelve months, there is not the fmalleft appearance of feparation, 
the mixture is ftill perfectly tranfparent and fluid in every part 
of it, though it be decidedly acid; and I know, that had it been 
boiled down toa proper degree, a feparation of the filiceous 
earth would have happened in a fhort time. I learned this by 
another experiment with Rykum water. To gr. 1000 of this 
~water, 1 added a quantity of acid more than fufficient for fa- 
turating the alkali. The water was then boiled tll it weighed 
only 138 grains, and it was fet up in my clofet to remain un- 
difturbed. In about eight days, the tranfparency of it was a 
little diminifhed, and afterwards there was a very flow fubfi- 
dence of the matter which had produced this effe@t. It formed 
gradually, at tht bottom, a ftratum of fome thicknefs, which ~ 
was a little lefs tranfparent than the clear water above, and was: 
thereby diftinguifhable from it. After a week or two more, I 
ce off the clear water entirely, without difturbing the fedi- 
ment, which was in fact a tender jelly, adhering to the bottom 
of 
