ZIN 
body, and is generally about thirteen inches 
tong, tiiough often far longer, and even 
weighing ten or twelve pounds. It is found 
in the Northern, Mediterranean, and Atlan- 
tic Seas, is extremely voracious, and subsists 
on insects, smaller fishes, and ova. It is in 
the highest estimation for the table in this 
country, but was little used before the mid- 
dle of the last century, See Pisces, Plate 
VI. fig. 6. 
Z. iusidiator, or the insidious dory, inha- 
bits the fresh waters of India, and is distin- 
guished by its mouth being more lengthened 
than that of any other species. The lower 
lip is said to be at pleasure contracted into 
a tube, through which this fish darts the 
fluid it takes in at the gills at various in- 
sects near the surface, thus embarrassing 
their wings, and suspending their flight, 
under which circumstances they easily be- 
come its prey. 
ZIERIA, in botany, so named in me- 
mory of John Zier, a genus of the Tetran- 
dria Monogynia class and order. Natural 
order of Rutaceae, Jussieu. Essential cha- 
racter ; calyx four-parted ; petals four ; sta- 
mina smooth, placed on glands; styles sim- 
ple , stigma four-lobed ; capsule four, unit- 
ed ; seeds arilled. This is one of the twenty 
new genera from the South Seas, the cha- 
racters of which are given by Dr. J. E. 
Smith. It is distinguished by having each 
of tlie stamens inserted into a large gland, 
and consists of shrubs with opposite, ter- 
nate leaves, and white flowers. 
ZINC, in chemistry and mineralogy, a 
metal unknown to the ancients, though they 
were acquainted with calamine, one of its 
ores, and the effect which this liad in con- 
verting copper into brass. Zinc has usual- 
ly been ranked among those metals, which, 
from their imperfect ductility and malleabi- 
lltj', were long denominated serai-metals. 
It was known, that by uniform pressure 
zinc might be extended into thin plates, 
and more lately, it lias been discovered, 
that, at a certain temperature, it has so 
much malleability and ductility, that it can 
be lamellated, and drawn into wire. For 
this iuvention a patent has been obtained 
by Messrs. Hobson and Sylvester, to the 
latter of whom this work has been in- 
debted for certain articles. See the Pre- 
face, 
The temperature at which zinc possesses 
these properties is between 210° and 300° 
of Fahrenheit, and by keeping it in an oven 
at this heat, it may readily be extended. 
By annealing, it retains tliis tenacity a» to 
ZIN 
be easily bent. At a higher temperature 
it is brittle, so as to fall to pieces under the 
hammer. Zinc is of a while colour, with a 
shade of blue, in a fresh fracture it is pos- 
sessed of considerable lustre, it is hard, 
and not easily cut with a knife. The spe- 
cific gravity is nearly 7.2. The ores of 
zinc are calamine and blende. See Cala- 
MiNARis. Calamine is an oxide, frequently 
with a portion of carbonic acid ; blende is 
a sulpliiiret, containing also some iron, and 
other extraneous matters. The ores of 
zinc are found in many countries, and in 
a number of mines in this country. The 
metal is obtained from the ore by distilla- 
tion. 
Zinc is melted by a moderate heat, and 
the fused mass, on cooling, forms regular 
crystals. Though scarcely altered by ex- 
posure to the air at a low temperature, yet 
it is rapidly oxydized by one amounting to 
ignition. When kept in a degree of heat 
barely sufficient for its fusion, zinc becomes 
covered with a grey oxide. But when 
throw'n into a crucible, or deep earthen 
pot, heated to whiteness, it suddenly in- 
flames, burns with a beautiful white flame, 
and a white and light oxide sublimes, hav- 
ing a considerable resemblance to carded 
wool. This oxide, however, when once de- 
posited, is no longer volatile ; but, if ex- 
posed to a violent heat, runs into glass. 
Zinc readily dissolves in sulphuric, nitric, 
and muriatic acids. With nitric acid, it 
yields nitrous gas, if the acid be concen- 
trated ; or nitrous oxide, if diluted. Snl- 
phiiric and muriatic acids, diluted with wa- 
ter, evolve, during their action on this me- 
tal, hydrogen gas; and the gas, when ob- 
tained, holds ill combination a portion of 
the metal. A stream of it has been found, 
if recently prepared, to occasion the fusion 
of the platina wire, though the pure gas is 
destitute of this property. This hydrogen 
gas, holding zinc, in solution, may also be 
obtained by a process of Vauquelin. A 
mixture of the ore of zinc, called blende, 
or calamine, with charcoal, is to be put 
into a porcelain tube, which is to be placed 
horizontally in a furnace, and, when red- 
hot, the vapour of water is to be driven 
over it. The gas that is produced, how- 
ever, is a mixture of carbonic acid, carbu- 
retfed hydrogen, and hydro zincic gas. The 
zinc is deposited on the surface of the wa- 
ter, by which this gas is confined ; but, if 
burned when recently prepared, the gas 
exhibits, in consequence of this impregna- 
tion, a blue flame. The solution of zinc in 
