FLOOR.] 
MINEllALS. 
3^ 
Tvhich is the series of Fluor Spar, and wliicli, with the Chloeides, the 
Iodides and Bromides, form a natural group occupying Cases 58 and 
59. Common Salt is associated here with the unique specimen of 
the Iodide and with the Bromo-iodide and Bromo-chloride of Silver^ 
from South America. The Cryolite, from Greenland, is introduced 
here : a mineral from which metallic Aluminium has been produced by 
a direct process, whereby metallic Sodium is made to set free and to 
become substituted for the Aluminium. Here, too, are the very rare 
minerals MatlocJdte and Mendijnte, which are " oxychlorides " of lead. 
The last Case in the collection, 60 and 60a, contains certain 
OEGANic COMPOUNDS, which, as occurring in the earth with constant 
and definite characters, find their place in a mineral collection. 
Amber is one of these, the resin of an extinct pine, to which sub- 
stance a value belonging only to the rarest gems was in ancient timea 
attached. 
NEVIL STOEY^MASKELYNE. 
