TRANSACTIONS OF SECTION B. 485 
29. Triphenylmethyl. By Professor TSCHITSCHIBABIN. 
pleny y y 
3. Copper Mirrors. By F. D. Cuarraway. 
‘The importance from the point of view of the health of the workpeople of 
obtaining a substitute for the tin amalgam used in the manufacture of mirrors 
has led many chemists to study the conditions under which metals are deposited 
from aqueous solution. These investigations have, however, usually had for their 
object the preparation of a liquid which would deposit a uniform and coherent 
layer of silver over a large glass surface at the ordinary temperature. Liebig was 
the first to solve this problem satisfactorily, and his method, in which milk sugar 
is the reducing agent, was formerly extensively used. 
Other metals are not so easily deposited, and copper, which from its close 
relationship with silver one would expect to behave similarly, has never been 
observed to be so laid upon glass. Although copper mirrors have never been 
obtained by deposition of the metal from an aqueous solution, Faraday’ about 
the time when silver mirrors were attracting much attention made the interesting 
observation that a mirror-like deposit could be obtained by dissolving a little 
oxide of copper in olive oil and heating plates of glass in a bath of this liquid up 
to the temperature at which the oil decomposes. The mirrors, however, obtained 
by Faraday’s method, if of any size, are liable to be stained or discoloured in 
patches by decomposition products of the oil, and they are, moreover, cenerally 
lacking in brilliancy. Further, as the deposition of the metal only takes place 
when the oil decomposes, the process is excessively disagreeable to carry out; and 
since the oil is spoiled it is also somewhat costly. 
In the course of an investigation on the oxidation of aromatic hydrazines, 
the author made the observation that when solutions of cupric oxide are reduced by 
these compounds the metal is deposited upon the glass in the form of a brilliant 
coherent film if clear vessels are used. 
The mirrors obtained by this method are very beautiful, as they show the 
lustrous red colour of burnished copper, and are as perfect in reflecting surface 
and as uniform as the similar mirrors obtained by the deposition of silver. 
It seems probable that this method of depositing copper upon glass could 
receive important application in the production of objects of art. 
4. Oxides of Carbon. By Dr. Boupovarn. 
The following substances are produced when carbon monoxide is heated at a 
temperature of 445° in the presence of a catalytic agent such as spongy platinum, 
nickel, or copper: (A) carbon dioxide; (B) a white crystalline substance, soluble 
in water, giving an acid solution; (C) a gaseous substance, soluble in water, which 
gives (B) on evaporation of its solution. 
Similar results were obtained on submitting a mixture of carbon monoxide and 
hydrogen to the action of heat in the presence of a catalytic agent. 
or 
. Report on the Transformation of Aromatic Nitroamines and Allied 
Substances, and its relation to Substitution in Benzene Derivatives. 
See Reports, p. 101. 
6. Report on the Study of Hydro-aromatic Substances. 
See Reports, p. 104. 
' Phil. Trans., 1857, p. 145. 
