I 
ZIN 
ZIR 
aiilphnric acid shoots into regular crystals. 
Tills salt is readily soluble, and its solution 
is not precipitated by any other metal. 
The muriate of zinc yields, when evapo- 
rated, an extract of thick consistence, hav- 
ing the viscidity of bird-lime. Zinc is oxy- 
dized also, when boiled with solutions of 
pure alkalies ; and a portion of the oxide is 
retained in solution. It is oxydized when 
mixed with nitre, and projected into a red- 
hot crucible. In this case a violent detona- 
tion ensues. 
Zinc combines with almost all the metals, 
and some of its alloys are of great import- 
ance. It may be united to gold in any pro- 
portion by fusion. The alloy is the whiter 
and the more brittle, the greater quantity 
of zinc it contains. An alloy, consisting of 
equal parts of these metals, is very hard 
and white, receives a fine polish, and does 
not tarnish readily. It has therefore been 
proposed as very proper for the specula of 
telescopes. One part of zinc is said to de- 
stroy the ductility of one hundred parts of 
gold. Platinum combines very readily with 
zinc. The alloy is brittle, pretty hard, ve- 
ry fusible, of a blueish-white colour, and 
not so clear as that of zinc. The alloy of 
silver and zinc is easily produced by fusion. 
It is brittle, and has not been applied to 
any use. Zinc may be combined with 
mercury, either by triturating the two me- 
tals together, or by dropping mercury into 
melted zinc. This amalgam is solid. It 
crystallizes when melted, and cooled slowly 
into lamellated hexagonal figures, with ca- 
vities between them. They are composed 
of one part of zinc, and two and a half of 
mercury. It is used to rub on electrical 
machines, in order to excite electricity. 
Zinc combines readily with copper, and 
forms one of the most useful of all the me- 
tallic alloys. The metals are usually com- 
bined together by stratifying plates of cop- 
per, and a native oxide of zinc combined 
with carbonic acid, called calamine, and 
applying heat. AVhen the zinc does not 
exceed a fourth part of the copper, the 
alloy is known by the name of brass. It is 
of a beautiful yellow colour, more fusible 
than copper, and not so apt to tarnish. It 
is malleable, and so ductile, that it may be 
drawn out into wire. Its density is greater 
than the mean. It ought to be by calcu- 
lation 7.6, but it actually is 8.4 nearly, 
so that its density is increased by about one 
tenth. When the alloy contains three parts 
of zinc and four of copper, it assumes a co- 
lour nearly the same with gold, but it is 
not so malleable as brass. It is then called 
pinchbeck, prince’s metal, or Prince Ru- 
pert’s metal. Brass was known, and very much 
valued, by the ancients. They used an ore 
of zinc to form it, which they called cadmia. 
Dr. AVatson has proved that it was to brass 
that they gave the name of orichalcum. 
Their aes was copper, or rather bronze. 
It is very difficult to form an alloy of iron 
and zinc. Malouin has shown that zinc may 
be used instead of tin to cover iron plates, 
a proof that tliere is an affinity between the 
two metals. Tin and zinc may be easily 
combined by fusion. The alloy is much 
harder than zinc, and scarcely less ductile. 
This alloy is often the principal ingredient 
in the compound called pewter. 
ZINNIA, in botany, so named in honour 
of John Godofr. Zinn, a genus of the Syn- 
genesia Polygamia Superflua class and or- 
der. Natural order of CompositEe Oppo- 
sitifoliae. Corymbiferae, Jussieu. Essential 
character : calyx ovate, cylindrical, imbri- 
cate ; florets of the ray five, permanent, 
entire; seed down, with two erect awns; 
receptacle chaffy. There are five species. 
ZIRCON, in mineralogy, the name of a 
genus, containing two species, viz. hyacintli 
and zircon : the former will be found in the 
alphabetical anangement ; we therefore 
proceed to the .species zircon, the chief 
colour of which is grey; but it occurs 
through all the varieties of green, blue, red, 
yellow, and brown. It is found commonly 
in roundisli angular pieces, which have al- 
most always rounded angles and edges. It 
is likewise crystallized. Specific gravity 
about 4.6. The constituent parts are, ac- 
cording to Klaproth, 
Zirconia 
Silica 
Oxide of iron 
Loss 
100.0 
It is infusible without addition by tlie 
blow pipe; with borax it forms a colourless 
glass. It is found in Ceylon, in the sand of 
a river, accompanied by crystals of spinelle, 
tourmaline, ceylanite. It is frequently cut 
as a precious stone, and employed for va- 
rious purposes, pui ticularly as an ornament 
in mourning dress. AVhen it is cut it exhi- 
bits, though in a very feint degree, the play 
of colours of the diamond. Some of the 
varieties are frequently used by watch- 
makers in jewelling watches. 
