A mineral, silica, SiO2. It has recently been used by C. V. Boys and
since by others in the making of filaments for torsion suspensions. The
mineral is melted, while attached to an arrow or other projectile. It is
touched to another piece of quartz or some substance to which it adheres
and the arrow is fired off from the bow. A very fine filament of
surpassingly good qualities for galvanometer suspension filaments is
produced.

As a dielectric it is remarkable in possessing but one-ninth the
residual capacity of glass.