Z E O 
z r n 
'otla ; the germina are about four ; the seeds, 
which are oblong and acuminated ou both 
Ikies, are as many. There is one species. 
[ ZANONIA, the name of a genus of plants 
(of the order diceeia, e ul class pentandria. The 
characters are these : it produces separate 
rnale and fem .Ie llovvers ; in the male flower 
the cup is a perianthiuin, composed of three 
leaves of an oval figure, expanding every 
Way, and shorter than the flower ; the flower 
Is monopetalous, but divided into five seg- 
ments, and has an open mouth ; the segments 
are jagged, and are equal in size, and bend 
backwards ; the stamina are five filaments of 
the length of the cup, standing open at their 
end, and terminated by simple apices; the 
female flowers grow on separate plants, and 
have the cup and flower the same as in the 
male, only that the cup ‘stands upon the ger- 
men of the pistil ; this germen is oblong, and 
from it are propagated three reflex conic 
its les ; the stigmata are bifid and curled ; the 
fruit is a long and very large berry, truncated 
at the end, and very small at the base ; it 
contains three cclis, and lias a curled suture 
near the apex ; the seeds are two, they are of 
an oblong figure and fiat. There is one 
species, the indiea. 
ZEA, Indian corn, a genus 'of plants of 
the class monoecia, order triandria. The 
male flowers are placed on distinct spikes ; 
the calyx is a biliorous, beardless glume ; 
the corolla is a beardless glume ; the female 
calyx is a bivalve glume, as is the corolla. 
There is one filiform, pendulous style ; the 
seeds are solitary" and buried in an oblong 
receptacle. There is only species, the Mays, 
or maize. The Indians in NewjEngland, and 
many other parts of America, had no other 
•vegetable but maize or Indian corn for mak- 
ing their bread. They call it weachin ; and 
in the United States of America there is 
(much of the bread of the country made of 
this grain, not of the European corn. In 
Italy, Germany, Spain and Portugal, maize 
constitutes a great part of the food of the poor 
inhabitants. 
The ear of the maize yields a much greater 
(quantity of grain than any of our corn-ears. 
There are commonly about eight rows of 
grain in the ear, often more, if the ground is 
good. Each of these rows contains at least 
thirty grains, and each of these gives much 
more flour than a grain of any of our corn. 
The grains are usually either white or yel- 
lowish ; but sometimes they are red, blueish, 
greenish, or olive-coloured, and sometimes 
striped and variegated. This sort of grain, 
though so essentially necessary to the natives 
of the place, is yet liable to many accidents. 
It does not ripen till the end of September ; 
so that the rains often fall heavy upon it while 
on the stalk, and birds in general peck it 
when it is soft and unripe. Nature has, to 
defend it from these accidents, covered it 
with a thick husk, which keeps off slight rains 
very well ; but the birds, if not frightened 
away, often eat through it, and devour a 
great quantity of the grain. 
ZEBRA. See Equxjs. 
ZENITH, in astronomy, the vertical 
point ; or a point in the heavens directly 
over our heads. 
ZEO-L1TE. This stone was first describ- 
ed by Cronstedt in the Stockholm Transac- 
tions for 1756. It is sometimes found amor- 
[phous and crystallized. The primitive form 
VOL. II. 
of its crystal is a rectangular prism, whose 
bases are squares. The most common va- 
riety is a long four-sided prism, terminated 
by low four-sided pyramids. 
Its texture is striated or fibrous. Its lustre 
is silkv. Refracts double. Absorbs water. 
Specific gravity 2,0S33. Colour white, often 
with a shade of red or yellow. When heated 
it becomes electric like the tourmaline. Be- 
fore the blow-pipe it froths, emits a phos- 
phorescent light, and melts into a white semi- 
transparent enamel, too soft to cut glass, and 
soluble in acids. In acids it dissolves slowly 
and partially without effervescence; and at 
last, unless the quantity of liquid is too great, 
it is converted into a jelly. A specimen of 
zeolite, analysed by Vauquelin, contained 
53.00 silica 
27.00 alumina 
9.46 lime 
10.00 water 
90.46. 
ZEUS, in ichthyology, a genus of fishes 
of the order of thoracic!. The head is 
compressed and declines, the upper lip being 
vaulted over by a transverse membrane ; 
the tongue is subulated ; there are seven 
rays in the gill-membrane; and the body 
is compressed. The species are eight; 
of which the most remarkable is the faber or 
doree. It is of a hideous form ; its body is 
oval, and greatly compressed on the sides ; 
the head large; the snout vastly projecting ; 
t he mouth very wide; the teeth very small; 
the eyes great, the i rides yellow ; the lateral 
line oddly distorted, sinking at each end, and 
rising near the back in the middle ; beneath 
it on each side is a round black spot. The 
tail is round at the end, and consists of fif- 
teen yellow rays. The colour of the sides is 
olive, varied with light blue and white, and 
while living is very resplendent, and as if 
gilt; for which reason it is called the doree. 
The largest fish we have heard of weighed 
twelve pounds. See Plate Nat. Hist. fig. 
421. 
ZIERlA, a genus of plants of the class and 
order tetrandria monogynia. The cal. is 
four-parted ; petals four; styles simple; caps, 
four; seeds aril led. There is one species, not 
deserving notice. 
ZINC. The antients were acquainted 
with a mineral to which they give the name 
of cadmia, from Cadmus, who first taught 
the Greeks to use it. They knew that when 
melted with copper it formed brass ; and that 
when burnt, a white spongy kind of ashes 
was volatilized, which they used in medicine. 
This mineral contained a good deal of zinc ; 
and yet there is no proof remaining that the 
antients were acquainted with that metal. 
The word zinc first occurs in the writings 
Paracelsus, who died in 1541. He informs 
us very gravely, that it is a metal, and not 
a metal, and that it consists chiefly of the 
ashes of copper. This metal has also been 
called spelter. 
Zinc has never been found in Europe in a 
slate of purity, and it was long before a 
method was discovered of extracting it from 
its ore. Henkel pointed out one in 1721 ; 
Von Swab obtained it by distillation in 1742 ; 
and Margraf published a process in the Ber- 
lin Memoirs in 1746. 
Zinc is of a brilliant white colour, with a 
6 A 
z i n m 
shade of blue, and is composed of a number 
of thin plates adhering together. When this 
metal is rubbed for some time between the 
lingers, they acquire a peculiar taste, and 
emit a very perceptible smell. Its hardness 
is six and a half. When rubbed .upon the 
fingers it tinges them of a black colour. Its 
specific gravity, after it has been melted^is 
6.861 ; after it lias been compressed 7.1908 ; 
so that its density is increased l-20th. 
This metal forms in a manner the limit 
between the brittle and the malleable metals. 
Its malleability is by no means to be com- 
pared with that of some of the metals ; yet 
it is not brittle, hke others. When struck 
with a hammer, it does not break, but yields 
and becomes somewhat flatter; and by a 
cautious and equal pressure, it may be redu- 
ced to pretty thin plates, which are supple and 
elastic, but cannot be folded without break- 
ing. This property of zinc was first ascer- 
tained by Mr. Sage. When heated to about 
400°, it becomes so brittle, that it may be 
reduced to powder in a mortar. 
It is not ductile. Its tenacity has not been 
ascertained. When heated to the tempera- 
ture of about 700°, it melts; and if the heat 
is increased, it evaporates, and may be easily 
distilled over in close vessels. When allowed 
to cool slowly, it crystallizes in small bundles 
of quadrangular prisms, disposed in all di- 
rections. If they are exposed to the air 
while hot, they assume a blue changeable co- 
lour. 
When exposed to the air, its lustre is soon 
tarnished, but it scarcely undergoes any other 
( change. When kept under water its surface 
'soon becomes black, the water is slowly de- 
composed, hydrogen gas is emitted, and the 
oxygen combines with the metal. If the 
heat is increased, the decomposition goes on 
more rapidly; and if the steam of water it> 
made to pass over zinc at a very high tem- 
perature, it is decomposed so rapidly, that 
very violent detonations take place. 
When zinc is kept melted in an open ves- 
sel, its surface Is soon covered with a grey- 
coloured pellicle, in consequence of its com- 
bination with oxygen. When this pellicle is 
removed, another soon succeeds it ; and in 
this manner may the whole of the zinc be 
oxidated. When these pellicles are heated 
and agitated in an open vessel, they soon 
assume the form of a grey powder, often hav- 
ing a shade of yellow. The powder has beets 
called the grey oxide of zinc. When zinc; 
is raised to a very strong red heat in an opeit 
vessel, it takes fire, and burns with a brilliant 
white flame, and at the same time emits a 
vast quantity 6f very light white flakes 1 liese 
are merely an oxide of zinc, 1 his oxide was 
well known to the antients. Bioscorides 
describes the method of preparing it. The 
antients called it pompholyx ; the early che- 
mists gave it the name of nihil album, lana, 
philosophica, and flowers of zinc. Dioscori- 
des compares it to wool. 
Two different oxides of zinc are at present 
known. 
The peroxide, or white oxide of zinc, is 
the oxide usually formed in the different pro- 
cesses to which the metal is subjected. We 
are indebted to Mr. Proust for an exact ana- 
lysis of this oxide and its combinations. It 
is composed ot eighty parts of zinc and 
twenty of oxygen, ft may be formed not 
only by burning zinc, but also by dissolving 
