FIRST FLOOR. 
59 
baster is a massive variety of gypsum (36h) ; owing to its white- General 
ness, fine texture, and softness, it is largely used as a material S^SgralT 
for statuettes and other indoor ornaments ; the Oriental ala- 
baster is a harder substance, stalagmitic calcite, the carbonate 
of lime. 
Borax (37c) is a hydrated borate of sodium. It is much used 
as a flux, also in the process of soldering, and in the preparation 
of easily fusible enamels. It was formerly carried over the 
Himalayas from a lake in Thibet, but is now obtained largely 
from borax lakes of the United States, and is extensively pre- 
pared from the boracic acid of the lagoons in Tuscany. 
Mtratine or Soda nitre (37d) is found in beds extending for 
many miles ; it is used for the preparation of nitric acid and of 
saltpetre, and now largely as a fertiliser. 
Calaite or Turquoise (38g) is a hydrated phosphate of alumi- 
nium ; it owes its blue or green colour to the presence of small 
quantities of salts of copper and iron. Being as hard as felspar 
and taking a good polish, it has been much prized in jewellery 
under the name of Oriental Turquoise ; that which comes into 
the market is chiefly brought from the turquoise mines, not far 
from Nishapur, in Persia. 
As a supplement to the collection of simple minerals, there is 
arranged, in cases 41 and 42, a group of natural substances 
which either belong or are closely related to the Mineral King- 
dom, although in their formation organised matter has played a 
very important part. The most important members are Coal 
and Amber. 
Coal (41a), in most of its varieties, gives structural evidence 
of its vegetable origin : its chemical composition depends on the 
more or less complete change which has taken place, and is thus 
not so definite as in the preceding minerals. In the variety 
called anthracite all traces of the original organised structure 
have disappeared. 
Amber (42c), in ancient times regarded as one of the precious 
stones, is likewise of vegetable origin. It is a fossilised resin, 
chiefly derived from trees allied to the existing pines : its 
originally viscous condition is sufi&ciently proved by the insects 
which are sometimes found enclosed in it. 
In the Pavilion at the east end of the gallery the visitor will 
