138 
XON-METALLIC MINEKALS. 
Canada — continued. 
448. PsiLOMELANE, Manganese 
Ore. 
De Toils Kloof, about 45 miles 
E.N.E. of Cape Town. 
Shelf VI. 
449 to 451. Three specimens of 
Chrome Iron Ore. 
Bolton, Canada. 
Shelf VIT. 
452. Magnetic Iron Ore. 
Madoc, Canada. 
I 453. Magnetic Iron Ore. 
i Marmora, Canada. 
i 454. Dolomite {Carbonate of 
Lime and Magnesia). 
! Canada. 
\ Xos. 449 to 454 presented by Sir W. 
j Logan. 
455. Specular Iron Ore {An- 
\ hydrous Peroxide of Iron), crystal- 
! lized. 
Ascension Island. 
Presented by Lieutenant McArthur. 
I This magnificent specimen stands under 
( a glass shade, on a small table, placed at 
1 present on the opposite side of the room. 
NON-METALLIC MINERALS. 
Horse-shoe Case. 
The discoveries of modern chemistry which have unveiled the true 
character of composition of many of the stony and sparry minerals, 
greatly modify the old distinction between metallic and non-metallic 
substances. But there is a certain convenience in adhering to the 
division recognized by the world at large, and in classing apart from the 
ores which yield the ordinary heavy metals of commerce those salts or 
oxides which in spite of a mere stony aspect are now known to contain 
one or other of the light metals, as sodium, aluminium, or magnesium. 
This great division of inorganic bodies includes those which are com¬ 
monly described as earths, salts, stones, spars, gems, and inflammables. 
Very numerous as they are, a great proportion of these minerals render 
important services to man, whilst along with them, either associated in 
their occurrence, or forming the natural links between separate kinds, 
are many for which no actual use has yet been devised. It is not the 
object of rlie present collections to rival the British Museum in the 
exhibition of every species and variety which has been established by 
scientific description ; but, whilst the chiefly important minerals are 
duly represented, especial prominence has only been given to those 
kinds which are applied to useful purposes. 
Case A. 
Carbon. 
The group of minerals which are composed chiefly of carbon, begins 
with the purest display of that element in the diamond, and in graphite, 
and includes the whole range of the coals, cannels, and lignites, in 
which besides the gases hydrogen, oxygen, and nitrogen, very variable 
quantities of earthy or stony matter, forming ash, are mingled in the 
