Daily Yellowstone journal., 1890-11-20
cHANceAele STONES
Peculiar Actions Of PArsdoxieal Pebbles
In the British Museum.

Peculiar Actions Of Pa1dexieaI Pebbles
In the British Museum.
Among the thousands of wonderful
things in the British museum none Is
more deserving Of q description than
the three little pebbles known to the
geologist of that institution as the
''changeable stones" The largest of
the three Is about the size of a cherry
stone and Of the same form, perhaps a
little NOR ovate. Lying in its little
glass case it appears to be perfectly
Opaque and of a yellowish color. Para
doxical as il may seem, it will scratch
glass if il is drawn across il, but can
itself be scratched with common pen
knife. The various acids have no ef-
feet whatever upon it, but strange to
relate. placed in water it soon becomes
perfectly transparent and Of a beauti-
full amber color.
The change begins almost immedi.
ately after the immersion at one end of
the ovate in the form of a minute shot
o bead, being in this way wholly I'M
like the two smaller ''changeable
stones" in which the transparency be-
gins around the edges and gradually
envelopes the entire stone. In the
large m the little globe like spot in
creases by degrees until the stone be,
comes uniformly clear throughout.
When removed from the water the end
first to become transparent is first to
become Opaque, the dark colored globe
gradually hiding the transparency Of
the whole stone.
Bergman. veltheim. Magellan and
Buchanan. all voluminous writers upon
the hydrophanes and other changeable
stones, tel us that some of the steatites
exhibit changes quite as astonishing as
those shown by thu three pebbles in
England great nat onal curiosity shop.
Buchanan aaaN Welt lein were the first to
particularly inquire into the nature Of
~steatite aNd ston,S Of similar compost.
ton. Their repprt on the remarkable
changes wrought upona piece of ~steatite
upon which thny were experimenting
may moi be wholly uninteresting to read.
ers who have a taste for the curious in
Its manifold forms.
Ii is rs follows: ".As soon as the
stone was placed in the water we noted
o peculiar musty smell, also that sew
eral air bubbles rose to the surface of
the water. Soon the first stont showed
signs of becoming transparent, then
several others were dropped into the
same vessel. Some of them became
colorlsss as soon as they were thor
oughly dampened; Others took on a
more or less deep yellow color; some
acquired a beautiful ruby hue, and
Others still the color of mother-of-
pearl or of a blush opal. Whatever
be the color of the liquid in which the
hydrophane is immersed. it gains only
its usual degree of transparency, with
the color peculiar to it. When we look
at it in its moist state we perceive a
luminous point, varying in its situation
as the position of the eye is altered.
The ancients also noticed the peculiar
little luminous spot in the steatites and
other hydrophanes, which was the
cause Of their calling such stones Ocu-
lus Mundi, they thinking the spot the
image of the sun. According TO Buck
man, it is not the immediate picture Of
the sun, but a reflection refracted into
the stone by the direct rays of old Sol,
which may serve to remind us that the
ancients knew a thing or two after all.
st. Louis Republic.