424 NOTICES OF THE MEETINGS [April 7, 
II. Another proposed use of the water-glass is that of hardening 
cements, mortars, §c., so as to render them impermeable by water. 
Fourteen years since Anthon* of Prague proposed several applica- 
tions of the water-glass. Among others he suggested the rendering 
mortars water-proof. He also suggests that this substance might 
be beneficially employed as a substitute for size in white-washing 
and staining walls. It was demonstrated by several experiments 
that carbonate of lime, mixed up with a weak solution of water-glass, 
and applied as a whitewash to surfaces, was not washed off by 
sponging with water, and that common whitewash, laid on in the 
usual manner with size, was rendered equally adhesive when washed 
over with water-glass. 
III. The Stereochrome of Fuchs. 
The formation of an insoluble cement by means of the water- 
glass, whenever the carbonic acid of the atmosphere acts on this 
substance, or whenever it is brought in contact with a lime-salt, has 
been applied by Fuchs to a most important purpose. The stereo- 
chrome is essentially the process of fresco seccot} invested with the 
capability of receiving and perpetuating works of the highest artistic 
character, and which may be executed on a vast scale.—Fuchs’s 
method is as follows :{— 
“ Clean and washed quartz-sand is mixed with the smallest quan- 
“ tity of lime which will enable the plasterer to place it on the wall. 
“© The surface is then taken off with an iron-scraper, in order to re- 
“move the layer formed in contact with the atmosphere ; the wall 
“ being still moist during this operation. The wall is then allowed 
“to dry; after drying it is just in the state in which it could be rubbed 
«« off by the finger. The wall has now to be fired, 7. e. moistened with 
«« water-glass.§ (An important point is not to use too much water- 
«« glass in moistening the wall.) This operation is usually performed 
“‘ with a brush. The wall must be left in such a condition as to 
“* be capable of receiving colours when afterwards painted on. If, 
‘as frequently happens, the wall has been too strongly fixed, the 
“© surface has to be removed with pumice and to be fixed again. 
« Being fixed in this manner the wall is suffered to dry. Before 
“the painter begins, he moistens the part on which he purposes to 
«‘ work with distilled-water, squirted on by a syringe. He then 
“paints: if he wishes to repaint any part, he moistens again. As 
* Neuere Mittheilungen tuber die Nutzanwendung des Wasser-Glases, 1840. 
This subject has also been fully treated by Kuhlmann in his ‘‘ Mémoire sur l’Inter- 
vention de la potasse ou de la soude dans la formation des chaux hydrauliques,” 
&c. 1841. Expériences Chimiques et Agronomiques. 
+ Vide Eastlake’s Materials for a History of Oil Painting, p. 142. 
t These particulars were obtained by Dr. Hofmann from Mr. Echter. A 
stereochromic picture by Echter and a sample of the water-glass as prepared in 
Munich were also exhibited by Dr. Hofmann. 
Per cent. 
§ The composition of the specimen produced was Silica 23.21 
Soda 8.90 
[The specific gravity of the solution 3.81.] Potass 2.52 
