120 Correspondence of J. Nickles. 
less common than upon the stone in the ordinary state. The report 
also states that tender stones have been rendered hard; they have lost — 
- part of their porosity, and afier being washed, they dry more rapidly 
~ 
than stones not silicified. The process has succeeded completely on 
all calcareous blocks, whether isolated or forming part of the structure, 
new and old. 
alteration. 
age by a galvanic deposit and make a kind of plate from which engra- 
vings could be taken. 
If, in place of arresting the process at a red heat, it is continued un- 
til the glass enters into fusion, the image sinks into the interior of the 
glass without being altered, and covers itself with a vitreous varnish. 
It appears like a design of great delicacy, enclosed between two plates 
of glass; and if positive proofs are employed, the method may 
used for making pictured glass which may without doubt be colored by 
the ordinary processes, 
Photographic Portraits on linen cloth.—The Revue Encyclopedique 
of the Abbe Moigno, from which we have taken the preceding note, 
states that the problem of making photographs on linen has been re- 
solved. The Abbé Moigno has assisted at the operations of M. Wulff, 
