chief ingredient in the enamel or exterior portion of the tooth.
Ancient ivory, having thus gained in its inorganic bases, becomes
deficient in the gelatinous constituents necessary to its
preservation. We recently had a singularly beautiful application of
the knowledge of this principle in the case of the ivory specimens
sent from Nineveh by Mr Layard. On their arrival in England, it was
discovered that they were rapidly crumbling to pieces. Professor Owen
recommended that the articles should be boiled in a solution of
albumen, which was done accordingly, and the ivory rendered as firm
and solid as when it was first entombed.

We may allude here to a very singular physical property which is
possessed by the elephant's tusk. Specimens have frequently been
obtained which were found to contain musket-bullets in their centre,
surrounded with a species of osseous pulp differing from the ordinary
character and constitution of ivory. There was frequently no
corresponding orifice on the surface of the tusk; and hence
Blumenbach, and other naturalists, were led to form some very
inaccurate notions regarding this circumstance. Mr Rodgers of
Sheffield some years ago forwarded a variety of such specimens to the
Edinburgh College Museum, and these were very closely examined by
Professor Goodsir, who, in a communication to the Royal Society of
Edinburgh, demonstrated that this arose simply from a property of
isolating foreign substances common to all osseous organised bodies:
the ball having been enclosed by the tusk in its pulpy secretion, and
corrosive action thereby prevented, the process of growth continued
without interruption.

Ivory is a solid, white, translucent substance, distinguishable from
bone by its beautiful texture of semi-transparent rhomboidal network.