242 IVORY AND THE ELEPHANT
dry wood to keep the piece circular; the rings are then cut from both ends, the two cuts meeting in the middle.*
but very rarely happens that a cross-section of the tusk forms a
perfect circle, or is perfectly round, the form generally
approximating an ellipse. The tusks are hollow for about one half of
their length, the thickness of the solid part growing gradually greater
until the tusk becomes a solid mass. The degree of curvature varies
much, some tusks forming an almost perfect semi-circle, while others
barely constitute the sixth part of a circle. Usually the curve is in
one direction only, but very occasionally it is in two directions.t
properly executed, turned-work ought not to need much polishing. For
this emery paper or fine glass paper may be used, after which the
surface can be rubbed with a mixture of whiting and water applied with
a bit of very thin wash leather; the surface should then be cleaned
with clear water. Finally, a very little oil may be applied. Î To
attach ivory to ivory or to wood a preparation of isinglass, sometimes
called "diamond cement," is often employed.
scrub ivory with Trent sand (a very fine sand) and water serves to rub
away the old surface, and this would be likely to do considerable
injury to any finely carved work. The best means of preserving the
original colour has been found to be exposure to the light under a
noted ivory worker of Copenhagen, Spangler, made the discovery that
ivory objects would retain their whiteness indefinitely if placed under
glass, to protect them from the air, and freely exposed to the effects
of light. The present
op. cit., Vol. I, p. 147,149,151. fHoltzapffel, op. cit., Vol. I, pp.
142,144. ÎHoltzapffel, op. cit., Vol. Ill, p. 1067; Vol. I, p. 154.
**Holtzapffel, op. cit., Vol. I, p. 153.