Mylius,^ in an alchemical treatise published in 1618, says of the turquois:

The turquois is a gem originating in Turkey. There aie two species of it: the Spanish and the Indian, but the
Indian is the best; while the other, being inferior, is not considered as valuable. Its color is a light or Venetian blue,
of a greenish luster or as if suffused with a lacteal fliiid; both are of a solid composition, but the Spanish is the more
obscure and thicker. It has the virtue of soothing the sense of vision and the mind (or heart), and of guarding against
all external dangers and accidents; it brings happiness and prosperity to its wearer. Suspended in a glass it sounds
the hour. When worn by the immodest, it loses all its power and color. ^

' Opus medico-chymicum. Tractatus II, Basilicae chymicae, lib. 4, cap. 13 (pp. 360-361). Francofurti, 1618.
2 Translated for the writer from the Latin by S. M. Gronberger.
25200°— 15 2



18 IVIEMOIRS NATIONAL ACADEMY OF SCIENCES. [vol.xii.
In 1628 Gui de la Brosse ' in Paris described odontolite or bone turquois, calling it a
"licorne minerale." "The Licorne," says he, "is a stone having the shape of a horn, and the
consistence of a stone, which, being exposed to a graduated heat, gives the true turquois."
This confusion between copper-stained bone and the mineral turquois, and the behef in the
transformation of the one into the other by the aid of heat, were very persistent and striking
features in the writings of many ensuing investigators, as noted below.
