Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 5, BUR-CHI

CAS [ 23
pi an fe a. them v 1th long clubs. As foon as one is defpatched,
he is fucceeded by feveral who come to the afliftance
of their unhappy companion, but come only to {hare
his fate. They are exceedingly tenacious of life, and
endure more than thirty hard blows before they die.
They will even live for feveral days after having re¬
ceived many mortal wounds. They are moft terrified
by fire and fmoke 5 and as foon as they perceive them,
retreat with the utmoit expedition to the fea. Thefe
animals grow fo very fat, that they look rather like
oil bags than animals. At Aftrakan is made a fort of
gray foap with their fat mixed with pot-afhes, which is
much valued for its property of cleanfing and taking
greafe from woollen fluffs. The greatefl numbers of
them are killed in fpring and autumn. Many fmall
veffels go from Aftrakan merely to catch feals.
If the Cafpian has few quadrupeds, it has in propor¬
tion ftill fewer of thofe natural productions which are
looked upon as proper only to the fea. There have
never been found in it any zoophytes, nor any animal
of the order of molufca. The fame may altnoft be faid
of fhells ; the only ones found being three or four fpe-
cies of cockle, the common mufcle, fome fpecies of
fnails, and one or two others.
But to compenfate this fterility, it abounds in birds
of different kinds. Of thofe that frequent the flrores,
there are many fpecies of the goofe and duck kind,
of the ftork and heron, and many others of the water
tribe. Of birds properly aquatic, it contains the grebe,
the crefted diver, the pelican, the cormorant, and al-
moft every fpecies of gull. Crows are fo fond of fifh,
that they haunt the fhores of the Cafpian in prodigious
multitudes.
The waters of this lake are very impure, the great
number of rivers that run into it, and the nature of its
bottom, affeCting it greatly. It is true, that in gene¬
ral the waters are fait: but though the whole weftern
Ihore extends from the 46th to the 35th degree of
north latitude *, and though one might conclude from
analogy that thefe waters v'ould contain a great deal
of fait, yet experiments prove the contrary : and it is
certain that the faltnefs ot this fea is diminiihedby the
north, north-eaft, and north-weft winds •, although we
mav with equal reafon conclude, that it owes its falt¬
nefs to the mines of fait which lie along its tv-o banks,
and which are either already known or will be known
to pofterity. The depth of thefe waters alfo dimi-
hiflies gradually as you approach the fhores, and their
faltnefs in the fame way grows lefs in proportion to their
proximity to the land, the north winds not unfrequent-
ly caufing the rivers to difcharge into it vaft quantities
of troubled water impregnated with clay. Thefe va¬
riations which the fea is expofed to are more or lefs
confiderable, according to the nature of the winds $
they affed the colour of the river waters to a certain
diftance from the fliore, till thefe mixing with thofe
of the fea, which then refume the afcendency, the fine
green colour appears, which is natural to the ocean,
and to all'thofe bodies of water that communicate
with it.
It is well known, that befides its fait tafte, all fea
water has a fenfible bitternefs, which muft be attri¬
buted not only to the fait itfelf, but to the mixture of
different fubftances that unite with it, particularly to
different forts of alum, the ordinary effect of different
5 J GAS
combinations of acids. Befides this, the waters of the Cafpian fea.
Cafpian have another tafte, bitter too, but quite di~ *
ftinCt, which affedts the tongue with an impreflion
fimilar to that made by the bile of animals ; a property
which is peculiar to this fea, though not equally fen¬
fible at all feafons. When the north and north-weft
winds have raged for a confiderable time, this bitter
tafte is fenfibly felt 5 but when the wind has been
fouth, very imperfectly. We ftiall endeavour to ac¬
count for this phenomenon.
The Cafpian is furrounded on its weftern fide by the
mountains of Caucafus, which extend from Derbent
to the Black fea. Thefe mountains make a curve
near Aftrakan, and directing their courfe towards the
eaftern ftiore of the Cafpian, lofe themfelves near the
mouth of the Jaik, where they become fecondary
mountains, being difpofed in ftrata. As Caucafus Is
an inexhauftible magazine of combuftible fubftances, it
confcquently lodges an aftoniihing quantity of metals
in its bowels. Accordingly, along the foot of this
immenfe chain of mountains, we fomelimes meet with
warm fprings, fometimes fprings of naphtha of dif¬
ferent quality ; fometimes we find native fulphur,
mines of vitriol, or lakes heated by internal fires. Now
the foot of Mount Caucafus forming the immediate
weftern ftiore of the Cafpian fea, it is very eafy to
imagine that a great quantity of the conftituent parts
of the former muft be communicated to the latter :
but it is chiefly to the naphtha, which abounds fomuch
in the countries which furround this fea, that we muft
attribute the true caufe of the bitte rnefs peculiar to
its waters ; for it is certain that this bitumen flows
from the mountains, fometimes in all its purity, and
fometimes mixed with other fubftances which it ac¬
quires in its paiTage through fubterranean channels,
from the moft interior parts of thefe mountains to the
fea, where it falls to the bottom by its fpeeific gravity.
It is certain too, that the north and north-weft winds
detach the grCateft quantities of this naphtha •, whence
it is evident that the bitter tafte muft be moft fenfible
when thefe winds prevail. We may alfo comprehend
why this tafte is not fo ftrong at the furface or in the
neighbourhood of the ftiore, the waters there being
lefs impregnated with fait, and the naphtha, which is
united with the water by the fait, being then either
carried to a diftance by the winds, or precipitated to
the bottom.
But it is not a bitter tafte alone that the naphtha
communicates to the waters of the Cafpian : thefe wa¬
ters were analyfed by M. Gmelin, and found to con¬
tain, befides the common fea fait, a cpnfiderable pro¬
portion of Glauber fait, intimately united with the for¬
mer, and which is evidently a produflion of the naph¬
tha.
As the waters of the Cafpian have no outlet, they
are difeharged by fubter^anean canals tbsough the
earth, where they depofite beds of fait ; the furface of
which correfponds with that of the level of the fea.
The two great deferts which extend from it to the eaft
and weft are chiefly compofed of a faline earth, in
which the fait is formed by efflorefcence into regular
cryftals •, for which reafon fait ftiowers and dews are
exceedingly common in that neighbourhood. The fait
of the marflies at Aftrakan, and that found in efflo¬
refcence in the deferts, is by no means pure fea lalt,
G g 2 • but