154 J, M. Ordway on Waterglass. 
Pour it out and dissolve in water, or better, in lye; and the sand 
or silex will be dissolved and changed into a thick water.” 
In 1825 there appear memoir in German “On a New and 
Useful Product Obtained from Silex and Potash, by Dr. Johann 
Nepomuk von Fuchs,” in which we find the following account 
of the first discovery of soluble glass, or, as Fuchs provision- 
ally named it, waterglass :—‘I obtained it first about seven years 
ago, in pouring concentrated potash lye on very finely divided 
silica which had been precipitated from liquor silicwm with sal- 
ammoniac, and well dried. The potash was absorbed by the 
silica with a sensible elevation of temperature, and the whole 
soon changed into a very firm, transparent, glass-like mass which 
proved to be permanent in the air. It did not occur to me that 
the same thing might also be produced by dissolving silica in 
potash and evaporating the fluid; since I then, and for a long 
time afterwards, held with all chemists the erroneous notion that 
a combination of silica and potash, to be permanent in the air, 
must be insoluble in water, and that a soluble product must 
necessarily be deliquescent. Two years afterwards, when I 
wished one day, for analytical purposes,—for which I first 
brought silicate of potash into use,—to prepare some as fully 
saturated with silica as possible, I learned to procure the sub- 
stance under consideration, by the method of solution. For 
this purpose I took freshly precipitated silica, poured on it as 
much potash lye as I judged to be necessary for its solution, 
and brought it to a boil. The silica very soon disappeared, and, 
in order to saturate fully the alkali present, to my no slight as- 
tonishment, I was obliged to add a quantity of silica still greater 
than I had taken at first. After this was done the solution was 
boiled a long time to concentrate it, and thus came to the con- 
sistency of syrup; and on the surface there appeared a tough 
pellicle which dried in the air to a transparent glass. All bod- 
ies which came in contact with this fluid received a glassy cov 
ering that attracted no moisture from the air but became much 
the harder and more brittle. From this I saw that the product — 
before me was the same which had been obtained before by the - 
process of absorption.” 
The author goes on to say that the burning down of the the- 
atre at Munich contributed to the completion of his discovery- 
For when the new building was to be erected, diligent inquiry 
was made for something to protect wood against fire; and many 
substances having been tested and rejected, it occurred to him 
* Novum Lumen Chymicum, Amstelodami, 1664. A somewhat earlier mention 
of the same substance is made by Van Helmont. J. F. Gmelin quotes the follow- 
ing passage from his * De Lithiasi,’ published in 1644 :—* Porro lapides, ge mae, 
arenae, marmora, silices, &c., adjuncto i vitrificantur: sin autem plure aleali 
coquantur, resolvuntur in humido quidem: at resoluta, facili negotio acidorum 
spirituum, separantur ab alcali, pondere pristini pulveris lapidum.” 
ee 
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