762 Marvels of the Universe 
polarizing light. 
Electric 
Organ 
Muscle 
are also known 
in a moment the 
pebble lenses. It is also useful on a larger scale for 
seventy-four parts 
difference between glass and 
Sulphur crystals consist of pure sulphur, an 
element found in a native state in proximity to 
volcanoes. Copper pyrites consist of a combination 
of sulphide of copper with bisulphide of iron. It is 
from this mineral that a great deal of the copper of 
commerce is obtained. Sulphide of antimony crystals 
as stibnite. The composition is 
of the element antimony and 
twenty-six of sulphur. The type used by printers is 
made of an alloy of antimony and lead. 
Vertebra. Fluor spar consists of calcium and fluorine in nearly 
equal parts. It 
is the source 
of hydrofluoric 
THE SKATE; 
A transverse section of the Skate showing the nature acid. It can 
and position of the electric organ. also be worked 
in the lathe and polished for ornamental purposes. Felspar 
consists of silica and alumina with potash. It forms one of 
the component parts of granite. _Decomposed felspar is a 
clay called kaolin, used for making porcelain. <A beautiful 
variety of felspar, known as labradorite, gives at various 
angles marvellous varieties of colour. Beryl is closely allied 
to the aquamarine, and is composed of silica, alumina and 
glucina. The finest beryl known was in Mr. Hope’s collec- 
tion and cost five hundred pounds. 
Chrysoberyl is composed of alumina and glucina. It is 
cut as agem. The specimens from Siberia are of an emerald- 
green colour and form the variety named Alexandrite. It 
shows remarkable colour effects. The hyacinth, resting in 
basalt, is a variety of zircon and is composed of silica and 
zirconia. Turquois is composed of alumina, phosphoric acid 
and water. Lapis lazuli, also called ultramarine, is composed 
of alumina, lime, soda, iron and sodium, etc. 
I am indebted to Dr. Max Bauer for the following ilus- 
trations: the diamond, emerald, topazes, amethyst, hyacinth 
and chrysolite. And to Dr. G. F. Kunz for those of the 
two tourmalines, ruby, sapphire and turquois. 
DIVAN Ge es Ciel Cry Ae RAS 
BY W. P. PYCRAFT, F.Z.S. 
Ir is now just over one hundred and twenty years since 
Luigi Galvani made his famous discovery of animal electri- 
city. The facts he brought to light were accounted then 
among the marvels of Nature; and though, in the course 
of years, an immense advance in our knowledge of the 
Electric Spe 
Nerve je = 
THE ELECTRIC STAR-GAZER. 
With the outer skin removed to show 
position and connection between the various 
organs of the head producing the electric 
current. 
