40 
NORTH GALLERY. 
[upper 
to the Museum by Sir Wm. Denison, the Governor of that Presi- 
dency. In Case B. are displayed, on the left extremity of the Case, 
the Siderolites, while the rest of the space is occupied by the 
Aero-siderites. The former are masses of meteoric iron containing 
stony matter ; the latter consist of the metallic alloy of iron and 
nickel, with small amounts of other metals, known as " meteoric iron." 
They also contain mechanical admixtures of compounds of these metals 
with phosphorus, and also with sulphur. The crystalline structure of 
the mass is often very effectively shown by the etching of the polished 
surface. On the north side of this room is seen the vast mass of 
meteoric iron found at Cranbourne, near Melbourne, in Australia, pre- 
sented by Mr. Bruce, of Inverquhomery, and weighing above 3| tons. 
At the east end of the gallery is one weighing 1,400 lbs., presented by 
Sir Woodbine Parish, found on the Grand Chaco, South America. 
The Collection of Minerals is arranged in four principal Divisions, 
These are — 
Div. I. The Native Elements. Cases 1, 2, 3, 4 (i.) 
Div. II. The Compounds of Metals, with Elements of the Arsenic 
Group (the Arsenoids, viz. Bismuth, Antimony, and 
Arsenic); or with elements of the Sulphur Group (the 
Thionids, viz. Tellurium, Selenium, and Sulphur); or 
with elements belonging to both groups. Cases 4 (ii.) 
to 12 inclusive. 
Div. III. The Compounds of Metals with elements of the Chlorine 
Group (the Halogen elements — Iodine, Bromine, 
Chlorine and Fluorine). Cases 13 and 14. 
Div. IV. Compounds of elements with Oxygen. Cases 15 to 60. 
These Divisions are again subdivided into sections and classes, the 
latter embracing the minerals which fall under the same general 
chemical denomination; as, for instance, the salts of the same acid or of 
a group of acids chemically and crystallographically equivalent to each 
other. Each class is further separated into distinct chemical series, 
the minerals included in any series being such as are designated by 
the same or equivalent typical formulas. Subordinated to this chemical 
system of classification is the final distribution of the several homotypical 
species of each chemical series, into distinct crystallographic series, 
arranged according to the crystalline system to which they belong ; the 
order of sequence of these systems being — 1st, the Cubic System; 2nd, 
the Dimetric or Pyramidal System ; 3rd, the Trimetric or Prismatic 
System ; 4th, the Hexagonal or Rhombohedral System ; 5th, the 
Monoclinic or Oblique System ; 6th, the Anorthic System ; and finally, 
Amorphous substances, that either present no crystalline forms, or 
the forms of which, if they be crystalline, are not determinable. In 
