Gems Notes and Extracts Augusto Castellani, Mrs. John Brogden 1871

HYDEOPHANE. 129porous. It takes a good polish. Its specific weightnever exceeds 2-3.What is most extraordinary with regard to this substanceis, that it adheres to the tongue, because itimbibes humidity easily.\\ hen immersed in water, it immediately gives outlittle bubbles of oxygen these were in the ; pores,which soon fill with water, renderingit thus clear andbright until dried up again by contact with the air.It is found in China, Arabia, Egypt, the Feroe Isles,Hungary, Silesia, Saxony, Piedmont, and in France.When analysed, it givesSilex 93Alumina .. .. .. 2Water .. .. .. 5From the increase of its weight, it is proved that itabsorbs the liquid in which it is immersed.Acids have no power over it, excepting tartaric acid,which makes the colour brighter. It is insoluble inether.It is found but seldom, and then in calcedony andopaline rocks, which must be broken in prodigiousquantities before finding a really fine hydrofane.This stone is but little used. It cuts smooth andthin, and is generally set clear, or without any backgroundof metal or talc ;so that, when immersed, allits properties may be better known and appreciated.