122 
POPULAR SCIENCE REVIEW. 
MINERALOGY, METALLURGY, AND MINING. 
Mineralogy . — It is curious to observe how often arsenic is found in connec- 
tion with sulphur and sulphur compounds. The composition of the arsenical 
sulphur from the solfataras of Naples has been investigated by Mr. T. L. 
Phipson. This mineral has an orange colour, owing probably to the 
selenium present. It is only partially soluble in bisulphide of carbon, 
which dissolves completely the crystallized sulphur of Sicily. It is found, 
on analysis, to contain 11 per cent, of arsenic, and per cent, of selenium. 
The arsenic is doubtless present as tersulphide. Arsenic is frequently 
found in iron pyrites (bisulphide of iron) ; and as sulphuric acid is now- 
prepared in large quantities from that mineral, the arsenic is carried on, 
and contaminates the acid. The mineral fahlerz, or tetrahedrite, which 
is mainly a sulphide of copper, frequently contains a large per-centage 
of arsenic. 
The isle of Elba appears to be an inexhaustible source of remarkable 
minerals. Some months ago crystals of garnet were found there, having 
a very peculiar form. They have recently been described by M. Luigi 
Bombicci and M. F. Pisani. Garnet crystals in general vary but little in 
form, the predominating faces being those of the rhombic dodecahedron 
and of the trapezohedron. In the crystals under consideration, however, 
the predominating form is the regular octahedron — the same which is so 
prominent in artificial crystals of alum. The octahedral garnet of Elba 
is found in serpentine rock, and is nearly always accompanied by chlorite 
and yellowish epidote. It has the colour of honey ; and the new method 
of spectrum analysis shows lime to be an important element. 
An analysis of some clays from the coast of Almeria, Spain, has been 
made by M. Terreil. They are suitable for porcelain. It is remarkable 
that they taste of chloride of potassium, although, from their proximity to 
the sea, one would expect the taste of chloride of sodium to be prominent. 
Along with them is found a red clay, which, from containing much more 
alumina and less silica than ordinary clay, possesses refractory properties 
in the highest degree. Hence it is suitable for furnaces — a very important 
point at the present time, when metallurgists have a difficulty in finding 
clays sufficiently fire-proof. Steatite has very recently been proposed as a 
substitute for fire-clay. 
Mica is coming into use in Paris for preserving, silvering, and gilding 
decorations in churches and public buildings. After being cut to the 
required thickness, it is coated with isinglass, and the gold or other sub- 
stances added. It is allowed to dry, and then glued or otherwise cemented 
to the object to be decorated. A burnisher of agate is used to make it 
smooth. 
Turning to metals , we find an announcement that Professor Chandler 
has discovered a new metal in the native platinum ox the Rogue River, 
Oregon. So far, only very minute quantities have been obtained, and 
further particulars are required. The discoverer believes it to be probably 
identical with the one discovered in 1852 by Dr. Genth among grains of 
platinum from California. 
