Chemistry and Physics. 317 
August, was found to be covered with black spots and streaks, 
some miscreant having attempted to disfigure it. At first 
the 
consisting of Drs. Max von Perrenkorer, ApoLtF BaxryeR, and 
CLEMENS ZIMMERMANN, was entrusted with the matter and em- 
owered to examine the question chemically and devise a method 
for restoring the statue. Onexamination about 300 of these black 
Spots, nearly all round and of the size of a hazel-nut, were counted 
upon the statue itself, fourteen being on the face. The granite 
base of the monument was similarly stained. On testing one of 
these spots, formed under one of the feet, the presence of man- 
OV 
of removing these stains, which penetrated some millimeters into 
the marble. The process finally determined on was to treat these 
a ¢ 
trated solution of soldi ayaseae After four hours the stains 
appeared fainter ; and on renewing the application, not the slight- 
st trace of the stain was observable on the following day. The 
Work was then carried forward uninterruptedly, and on the 13th of 
December the statue was completely restored to its original purity 
and beauty; a result confirmed by the authoritiés on the 22nd in 
a Liebig potash bulb and a series of U-tubes containing pumice 
soaked in potash, caustic potash in sticks, pumice moistened with 
Sulphuric acid and phosphoric oxide, the junctions being made with- - 
out rubber. Bohemian tubes proving too soft at the tet t 
; duired, tubes of porcelain were used in the combustion, being 
heated by a Wiesnegg combustion furnace: The products of com- 
