PEA 
PEA 
aquafortis and the lapidaries mill. Mother 
of pearl is used in inlaid works, and in seve- 
ral toys, as snuff-boxes, &c. 
Peaui,, in heraldry, in blazoning with 
precious stones, is the same with argent, or 
white. 
Peari. ash, an alkali used in various ma- 
nufacturing processes : it is potash mixed 
with different heterogeneous substances. 
See Potash. 
Pearl fishery. The most important 
fishery to England at present is that at 
Ceylon. The origin of this method of pro- 
curing a valuable ornament for the person 
must have arisen from accidentally discover- 
ing the pearl within oysters taken for food 
is evident ; but it is impossible to ascertain 
when the search became systematical,tlioiigh 
it is extremely probable it has been so for 
very many ages. 
The pearl oysters of the coast of Ceylon 
are all of one species, and possess the same 
regularity of form; but tliey assume dif- 
ferent qualities, and have different denomi- 
nations, suited to the nature of the ground 
where they are situated, and from the ap- 
pearance of zoophytes adhering to the ex- 
ternal surface of their shells. They resemble 
a cockle in shape, which is an imperfect 
oval, and their circumference is generally 
about nine inches and a half, having a seg- 
ment as it were cut off where the joint of 
the two shells occurs. The interior of thosd 
is far more brilliant and beautiful than the 
pearl they enclose, and the outside is 
smooth, except when injured by the usur- 
pations of sponges, corals, and other marine 
productions. The flesh of the animal is 
white, and of a glutinous consistency. 
Perhaps no class of animated nature un- 
dergoes more unmerited persecution and 
destruction thaii tlie pearl-oyster; when 
situated in their native regions, they afford 
a foundation for the habitations of other 
animats, and millions of them are dragged 
from their banks, and thrown away, for 
what they are vainly supposed to contain, 
and that an intruder or a disease. One of 
the banks at Ceylon furnishes oysters to 
which zoophytes are attached, apparently 
belonging to the class of sponges, and those 
generally resemble a funnel or cup, and 
grows to a size that completely overshadows 
the oyster ; others of different banks have a 
substance adhering to them tinged with red. 
The above are found to contain the finest 
pearls ; some escape free from incumbrance, 
and thousands are compelled to bear trees of 
coral on them of five times their own weight. 
The oyster is fastened to the rocks at the 
bottom of the sea by quantities of hairy 
fibres. By this means they are not readily 
swept from their original station, and yet 
possess the advantage of being conveyed to 
some distance from it by the motion of the 
water; besides they are connected to each 
other in the same manner. It frequently 
happens that an old oyster, surrounded by 
young ones, is brought up by the divers, 
and the latter have been ascertained to pos- 
sess, even when little larger than a grain of 
sand, the power of moving themselves by 
the extension and contraction of what is 
termed the beard. The violence of the 
waves at the time of the monsoons occasions 
great changes in the state of the banks, 
when incredible numbers of them are buried 
by the shifting of sand, and that is some- 
times removed by the same power acting 
in a contrary direction. 
It is supposed, from many concurring 
circumstances, that the pearl-oyster arrives 
at maturity at the close of seven years: 
after this period it is imagined that it dies, 
when the body decaying is washed away by 
the sea : a bed was discovered a few years 
since composed almost wholly of empty 
shells. The precious substance, which in- 
vites the exertions of man to obtain it, has 
been generally supposed to be a disease 
peculiar to the animal ; but were this the 
fact, it is extremely prevalent amongst this 
description of oysters, as every individual 
of the species is found to be accompanied 
by a certain proportion of minute particles, 
which are evidently the pearl in the first 
stages of formation ; hence it may be fairly 
supposed, that they are in some essential de- 
gree useful, rather than prejudicial to the in- 
habitant of tlie shells, of the nature of which 
it decidedly partakes, and is composed of a 
number of layers, moveable by a skilful 
person to the improvement of tlie pearl, as 
it sometimes happens the exterior coat only 
may be discoloured or injured. When the 
pearl is in a state of perfection they are of 
a brilliant white, some have been found of a 
beautiful tint of pink, of the colour of gold, 
and a few entirely black. These variations 
are, however, very uncommon. 
The pearls are discovered near the angles 
of the shell, and close to the hinge, where 
the animal is most thick and fleshy ; they 
are generally numerous, and in some in- 
stances 150 have been taken from one oys- 
ter; on the other hand, an hundred oysters 
have been opqned w'hence a pearl could not 
be extracted fit for any purpose whatever. 
