262 FIRST FORMS OF VEGETATION. 
the Otomacs gather on the shores of the Orinocoand 
Meta, and eat by way of a bonne bouche after their 
regular meals ; the yellowish earth called caouac 
found in Guinea, of which the negroes are passion- 
ately fond; the kieselguhr or meerschaum, found 
in Hamburg and Turkey, and employed in the 
manufacture of pipes, and also recently on account 
of the extraordinary greed with which it absorbs 
and retains nitro-glycerine,as a mechanical medium 
or vehicle in the conversion of that explosive 
liquid into the safer and more useful form of solid 
dynamite ; and the polierschiefer, or polishing 
stones, the elements of which consist chiefly of remnants of micro- 
scopic living beings. In the year 1839, Biot read before the 
Academy of Sciences in Paris a treatise, containing everything that 
was then known on this subject, to which his son, the Oriental 
linguist, Biot, furnished translations from Chinese and Japanese 
works, From Schott, in Berlin, Professor Ehrenberg obtained, in 
addition, the following information, taken from Chinese sources. 
The first mention of edible earth dates from the year 744 after 
Christ, and is contained in the Chinese work, Pen-tsao-kang-mu, 
where it is called Schimian, Stone-bread, or Mi-anschi, Bread- 
stone; the article in the Japanese Excyclopadia, which Biot has 
translated, is taken from this work. The Pen-tsao says, according 
to Schott, that stones contain several substances which are edible, 
especially a yellow meal and fatty liquid, which is contained in the 
Yu (a stone), and is therefore called the fat, marrow, or mucilage 
of the white Yu. An earthy substance, prolonging life, and called 
Schi-nao, is found in the very smooth stone Hoa-shi, which is sup- 
posed to be Steatite, and may perhaps be decomposed Steatite. 
The Schimian is only used as a substitute for bread in times of 
scarcity, when it is miraculously found in different localities, as is 
believed. The Imperial annals of the Chinese have always re- 
ligiously noticed its appearance, but have never given any descrip- 
tion of the substance. The Pen-tsao quotes, under the Emperor 
