ZINNIA. 
zinc obtained by the combustion of the metal, is 
a light flocculent powder, inodorous, insipid, in- 
fusible in the fire, insoluble in water or in alco- 
hol, unalterable in the air, and of a pure white 
colour at common temperatures, but yellow while 
cooling from a state of lowered heat. It is a 
strong salifiable base, combining readily and 
thoroughly with acids, and forming regular salts, 
most of which are colourless. It combines also 
with some of the acids. It appears to consist of 
one equivalent of zinc and one equivalent of oxy- 
gen; but it often contains small portions of car- 
bonic acid; and, as sold in the shops, it is not 
unfrequently adulterated with chalk or with 
white lead. It possesses tonic and antispasmodic 
properties; and has been given in very minute 
doses in cases of chorea, epilepsy, and hooping- 
cough ; and is the active ingredient in a mode- 
rately astringent and stimulating ointment for 
the cure of ringworm and of chronic inflamma- 
tion of the eyes. 
The acetate of zinc is formed in a state of solu- 
tion by mixing a solution of sulphate of zinc 
with a solution of acetate of lead in proper pro- 
portions,—the bases and the acids of the two salts 
making a mutual interchange of combination, 
and the resulting sulphate of lead being thrown 
down as a precipitate; and the solution of the 
acetate of zinc thus formed has long been known 
as a valuable application for chronic ophthalmia. 
—A tincture of the same salt is made in a some- 
what similar but more operose manner; and 
serves also in dilution as a good external astrin- 
gent; and might likewise be advantageously em- 
ployed as an internal remedy for debility in the 
digestive system. 
The chloride of zinc, popularly called butter of 
‘zine, is formed by the combustion of zinc filings 
in chlorine gas, and may be obtained also by 
evaporating muriate of zinc to dryness, and then 
heating it to redness in a glass tube. It con- 
sists of one equivalent of zinc and one equivalent 
of chlorine; it has a soft consistence,—alluded 
to in its popular name of butter; and it deli- 
quesces on exposure to the air, being then recon- 
verted into muriate.—Bromide and iodide of zinc 
may be formed in a similar way to the bromide 
and the iodide of iron. 
ZINGIBER. See Ginerr. 
ZINNIA. A genus of handsome, hardy, Ame- 
rican annual plants, of the sunflower division of 
the composite order. Hight species, all about 2 
feet high, have been introduced to Britain. The 
few-flowered, 7. pauciflora, is the longest known, 
and has sessile yellow flowers; and all the others 
have pedunculate and either red or scarlet flow- 
ers; while the elegant, Z. elegans, comprises both 
a splendid scarlet-rayed variety and a white- 
rayed variety. The many-flowered, Z. multiflora, 
blooms so long as from June till October, and 
the elegant from June till September ; and the 
others bloom either in July and August or in 
ZOOLOGY. 793 
leaved, the revolute, and the hybrid thrive in 
any common soil; and the others, in order to do 
well, require a soil of rich mould. The elegant 
combines breadth and beauty of flower more than 
most hardy or half-hardy annuals ; and is a high 
favourite with many amateur florists, both for 
the open ground and for small selections of house | | 
annuals, 
ZIRCONIUM. A rare and simple metallic or 
quasi-metallic substance,—the base of the earth 
zirconia. It is prepared from hydrofluate of zir- 
conia with the aid of potassium, potash, and the 
spirit-lamp; and was first obtained in a separate 
state in the year 1824, It is a black powder, 
capable of being pressed into thin shining scales, 
but with very slight metallic lustre and very 
feeble coherence of its particles; it does not con- 
duct electricity; it does not oxidize when boiled 
in water; it yields with great reluctance to the 
action of sulphuric, muriatic, and nitro-muriatic 
acids; it readily dissolves in hydro-fluoric acid, 
with disengagement of hydrogen; and when 
heated in the open air, it ignites before becom- 
ing luminous, burns with a bright flame, and is 
converted into zirconia. 
Zirconia was discovered in 1789 by Klaproth 
in Ceylon. It has a similar appearance to alu- 
mina ; is tasteless, odourless, insoluble in water, 
and so hard that it will scratch glass; it has a | 
specific gravity of 4:3: and, when pure, is of a | 
white colour,—but generally exhibits a yellowish 
tinge in consequence of the presence of iron. It | 
becomes vividly phosphorescent when strongly | 
heated before the blow-pipe ; it combines with 
acids to form salts, similar in most respects to 
those of alumina,—but precipitable from solution 
by any of the pure alkalies; and, when thrown 
down from any of its salts by ammonia, and af- 
terwards ignited, dried, or even washed with — 
boiling-water, it acquires the power of completely 
resisting the action of the acids. 
ZIZANIA. See Canava Rice. 
ZIZIPHORA. A genus of ornamental exotic 
plants, of the labiate order. 
six annual species have been introduced to Bri- 
tain from Siberia, Caucasus, Tauria, Spain, and 
the Levant ; and several more are known. The 
introduced species are hardy, and vary in height 
from 6 to 18 inches, and present more or less 
close resemblances to thyme, basil, savory, and 
pennyroyal, at once in foliage, flower, and fra- 
grance ; and have either red, purple, lilac, or 
pink flowers. The perennials have a trailing 
habit and are suitable for rockwork ; and three 
of them, the thick-flowered, the mediate, and the 
serpyllum-like, are evergreens, and may be pro- 
pagated from cuttings. All the annuals will 
thrive in any common soil. 
ZIZYPHUS. See Jususer. 
ZOOLOGY. That part of natural history which 
treats of animals. It is not confined to a de- 
scription of the external forms of animals, but 
Four perennial and || 
|| June and July. The slender-leaved, the narrow- | embraces all the phenomena of life and animal - 
