massive, but not unfrequently chrystallized 
in pretty oblique six-sided prisms, the chrys- 
tals seldom large, but internally shining and 
Splendent. Fig. 24. 
Selenite is completely transparent, soft, 
somewhat flexible, not very frangible, and 
is found in the oldest gyps formation, in 
single cbrystals in clay beds in the newest 
formation, and in other situations. It is 
common in Thuringia, at Montmartre near 
Paris, Shotover near Oxford, and in the isle 
I of Sheppy. It is employed in taking the 
I most delicate impressions, for crayons and 
I other purposes. 
Twentieth species. Cube spar. 
The colour is milk-white with various allied 
| shades. It is massive, occurring in large, 
coarse, and small ground distinct concretions. 
| The lustre is shining, passing into splendent, 
| translucent, sottish, very easily frangible, and 
I not particularly heavy. It is found in salt 
rocks in Salzbourg. 
To the calc genus are also referred phos- 
; phorite, which forms a great bed in Estrema- 
; dura in Spain ; and the anhydrite, found in 
i the duchy of Wirtemberg. 
Seventh genus. 
Baryte Genus. 
First species. Wither it e 
Is commonly of a light yellow ish-grey co- 
\ lour, generally massive, but sometimes chrys- 
j Utilized in six-sided prisms, or double six- 
j sided pyramids. The lustre of the principal 
| fracture is shining; the fragments generally 
I wedge-shaped, it is translucc nt, somewhat 
| semihard, brittle, easily frangible, and pretty 
! heavy. Figs. 25 and 26. 
It melts, without addition, before tire blow- 
pipe, into a white enamel, and occurs in veins 
along with heavy spar, lead-glance, & c. at 
Angiesark in Lancashire. Combined with 
muriatic acid, it may be used in medicine, 
though a very active poison ot itself. 
Stcond species. Heavy spar or baryte. 
See Barytes. 
Eighth genus. 
Strontian genus. 
First species. Strontian. 
The usual colour is intermediate between 
asparagus and apple-green ; it occurs most 
commonly massive, but sometimes chrystal- 
Jized in a circular six-sided prism. The 
chrystals are scopiformlv and manipularly 
aggregated. The lustre of the principal 
fracture is shining, of the cross fracture glisten- 
ing. It is translucent in a greater or less 
degree, soft and semihard, brittle, easily 
frangible, dissolves in acids with efferves- 
cence, and occurs along with lead-glance, 
heavy spar, &c. at Strontian in Argyleshire, 
the only place where it has yet been found. 
Second species. Celesiine 
Is divided into two sub-species : 
1. Fibrous celestine, is of an intermediate 
colour, between indigo-blue and blueish-grey; 
it occurs massive and in plates, and alsochrys- 
taliized, shewing a tendency to prismatic 
distinct concretions ; is translucent, soft or 
semi-hard, easily frangible, and pretty heavy. 
It is found in Pennsv lvania and in France. 
2. Foliated celestine, is of a milky-white 
colour, falling into blue ; it occurs massive, 
.and also chrv slallized in six-sided tables in- 
VOL. II. 
MINERALOGY. 
tersecting each other. It has a glistening 
lustre, is strongly translucent, sottish, not 
particularly brittle, easily frangible, and hard. 
It occurs sometimes in sulphur beds, and is 
found very finely chrystallized in Sicily, and 
likewise near Bristol. Fig. 27. 
CLASS II. 
Fossil Salts. 
The substances included in this class are 
confined to those which are found in a natu- 
ral stale only; and the greater part of them 
appear to be formed by the agency of water, 
air, Ac. 
The distinguishing characters of fossil salts 
are, their taste and easy solution. They re- 
semble each other so closely, that the term 
saline consistence is used to express whatever 
relates to hardness, tenacity, and frangibility. 
First species. Natron, or Natural Soda. 
It may be divided into the two following 
sub-species : 
1. Common natron, is of a yellowish or 
greyish-white colour, occurs in line fiakes or 
in dusty particles, has a sharp alkaline taste, 
effervesces with nitric acid, is easily soluble 
in water, and strikes blue vegetable tinctures 
green. It occurs as an efflorescence in the 
surface of soil, or on the sides and bottoms of 
lakes that occasionally become dry. It is 
found in very large quantities in Hungary, 
Bohemia, and Egypt, and in many other 
countries of the Old World. 
2. Radiated natron, or natural soda, is of 
a greyish or yellowish-white colour, occurs in 
crusts or chrystallized in capillary or acicular 
chrystals, is glistening and translucent, and is 
found in large quantities in the province of 
Sukana in Barbary, and in Southern Africa. 
Natron is principafly employed in the ma- 
nufacture of glass, soap, and for washing. It 
is also used as a llux after being purified. 
Second species. Natural nitre. 
The colour is greyish or yellowish-white, 
approaching to snow-white; it is tiaky, some- 
times verges to solid and massive, is of a sa- 
line consistence, and tastes saltly cooling. 
Placed on hot iron, it hisses and detonates ; 
is usually found in thin crusts on the surface 
of the soil at particular seasons of the year, 
particularly in hot climates. It is also met 
with in various countries of Europe, and is 
much used in making gunpowder, in medi- 
cine, and the arts. The greatest part, how- 
ever, employed for those purposes, is an ar- 
tificial preparation from the refuse of animal 
and vegetable bodies undergoing putrefac- 
tion, and mixed with calcareous and other- 
earth. 
Third species. Natural Rock-salt 
Is divided into two sub-species : 
1. Rock or stone-salt, which is of two 
kinds, foliated and fibrous. The former is 
commonly of a white or grey colour, occurs 
massive and disseminated, and also chrystal- 
lized in cubes ; in general is strongly translu- 
cent, rather hard,, easily frangible, and feels 
somewhat greasy. The latter is greyish, 
yellowish, and snow-white'; occurs massive, 
is strongly translucent, verging to semitrans- 
parent, decrepitates when laid on burning 
coals, and is found in beds lying over the first 
or oldest floetz trap formation. It forms 
whole hills at Cordova in Spain, is found also 
in Germany, and almost every country in the 
D d * 
ong 
world. At Nantwich in Cheshire it has long 
been dug. Its use is as general as its disse- 
mination. Tt is employed as a daily season- 
ing for our food, as a manure, in various ma- 
nufactures, and for purposes too numerous to 
mention. 
2. Lake-salt occurs either in thin plates, 
which are formed on the surface of salt-lakes, 
or in grains at their bottom. It is translu- 
cent, and of a saline consistence. It is found 
in Cyprus, near the Caspian Sea, and in va- 
rious parts of Africa. 
Fourth species. Natural sal ammoniac. 
The colour is commonly greyish or yel- 
lowish-white. It is of a saline consistence, 
and is flaky, with an urinous taste. It is 
sometimes found massive, stalactitic, tube- 
rose, b< tiyoidal, and chrystallized. It is the 
product of volcanoes and pseudo-volcanoes, 
and is found in Italy, Sicily, in the vicinity 
of inflamed beds of coal both in England and 
Scotland, and in several countries of Asia. 
Fifth species. Natural Epsom salt. 
Colour a greyish-white. It occurs in ca- 
pillary efflorescences, and is mealy or tiaky, 
of a saline consistence, and taste saltly bitter. 
It is found as an efflorescence on clayey’ 
stones or gyps rocks, at Sena, at Solfatara, in 
Hungary, and Bohemia. It is also contained 
in many mineral springs, particularly those 
of Epsom, whence it derives its name. Ep- 
som salts are much used as an easy purgative. 
Considerable quantities of magnesia may be? 
obtained from them. 
Sixth species. Natural Glauber salt. 
The colour is usually greyish and yellow-*, 
ish-white. It occurs in the form of mealy 
efflorescences, in crusts, and sometimes chry- 
stallized in acicular and in six-sided prismatic 
chrystals. Internally it is shining, with a vi- 
treous lustre, is soft, brittle, easily frangible* 
and has a cooling but a saltly bitter taste. 
It is found on the borders of salt-lakes, 0:1 
moorish ground, on old and new-built walls 
in different countries of Europe, Asia, and 
Africa, and is used as a purgative medicine, 
and in some places as a substitute for soda iu- 
the manufacture of white glass. 
Seventh species. Natural alum 
Is of a yellowish or greyish-white colour ; 
occurs as a mealy efflorescence, or in deli- 
cate capillary chrystals ; has a sweetish astrin- 
gent taste, and is produced in various situa- 
tions in Scotland, Germany, Italy, Spain, 
Sweden, and in Egypt. 
Alum is employed as a mordant in d vein 2 ', 
in the manufacture of leather, as a medicine, 
for preventing wood from catching fire, and 
for preserving animal substances from putre- 
faction. 
Eighth species. Flair salt. 
The principal colours are snow, yellowish, 
and greyish-white. It occurs in delicate ca- 
pillary chrystals, lias a saline consistence, 
and a sweetish astringent taste. 
Hair salt is found in different mine coun- 
tries on the continent, at Whitehaven in 
England, and near Paisley in Scotland, and 
bears a striking resemblance to fibrous gyps. 
Ninth species. Rock butter. 
The colour is light-yellow or greyish-white. 
It occurs massive and tuberose, "is translu- 
cent, has a saline consistence, or sweetish-*mur 
