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THE ALLOTROPIC CONDITIONS OF SILVER.


M. Berthelot recently called the attention of the Academy (Paris) to
the memoirs of Carey Lea on the allotropic states of silver, and
exhibited specimens of the color of gold and others of a purple color
sent him by the author. He explained the importance of these results,
which remind us of the work of the ancient alchemists, but he reserved
the question whether these substances are really isomeric states of
silver or complex and condensed compounds, sharing the properties of
the element which constituted the principal mass (97-98 per cent.),
conformably to the facts known in the history of the various carbons,
of the derivatives of red phosphorus, and especially of the varieties
of iron and steel. Between these condensed compounds and the pure
elements the continuous transition of the physical and chemical
properties is often effected by insensible degrees, by a mixture of
definite compounds.

The following letter appears in a recent number of the _Chemical
News_.

_Sir_: In a recently published lecture, Mr. Meldola seems to call in
question the existence of allotropic silver. This opinion does not
appear, however, to be based on any adequate study of the subject, but