792 
Britain; and they love a soil of sandy peat, and 
are propagated by radical division. 
ZINC. An abundant and very useful metal. 
It occurs in a metallic state, combined with sul- 
phur and iron, in the form of blende; and in an 
oxidized state, combined with silica, in the form 
of red zinc ore,—and combined with carbonic 
acid, in the forms of electric calamine and com- 
mon calamine. The sulphuret or blende com- 
prises three varieties,—yellow, brown, and black ; 
and the common calamine also comprises three 
varieties, — crystallized, compact, and earthy. 
Zinc was not known to the ancient Greeks, 
though contained in the cadmia which they used 
in the manufacture of brass; nor was it known, 
in its proper or separate state, to any Europeans 
previous to the third decad of the eighteenth 
century, though abounding in ores and minerals 
with which multitudes of them were familiar, It 
seems indeed to have been worked and used from 
a somewhat remote period by the Hindoos and the 
Chinese; but it was not obtained in a separate 
state in Europe till the year 1721, and was not 
obtained by the process of distillation till 1742. 
The ores of it occur in the carboniferous lime- 
stone and magnesian limestone formations in 
England and in many other parts of the world; 
and are usually associated with the ores of other 
metals, particularly those of iron, lead, copper, 
arsenic, and cadmium. It is procured in large 
quantities from calamine, and in still larger ones 
| from blende, by means of heat and carbonaceous 
matters, in the process technically called distilla- 
tion by descent,—the blende being first crushed, 
| picked, and roasted. “The ore is then washed 
to separate the metallic particles from the lighter 
parts; and is then ground in a mill with one- 
eighth of its weight of charcoal; and put into 
‘large earthen jars placed in a circular furnace, 
through the bottom of each of which passes an 
iron tube, which goes through the floor of the 
furnace into a vessel of water placed beneath. 
The cover of each jar is firmly and. accurately 
luted on, so that the reduced zine, as it is ele- 
vated by the strong heat of the furnace, not find- 
ing a vent to escape by the top, descends through 
the iron tube into the water, and is there con- 
densed in small metallic drops, which are after- 
wards melted and cast into ingots.” The por- 
tions which first come over are generally very 
impure, containing admixtures of arsenic and 
cadmium ; and the succeeding continue to be of 
the same character so long as the vapour burns 
with what the workmen call a brown blaze,—and 
should all be rejected as unfit for any of the or- 
dinary uses of zinc;—and even the subsequent 
and best portions, or those which rise during 
what the workmen call the blue blaze, are never 
quite pure,—always containing some iron, and 
often containing also traces of arsenic, cadmium, 
lead, copper, charcoal, and sulphur ; but they can 
be freed from their impurities by afterwards ex- 
ZINC. 
with its receiver full of water, and there subject- 
ing them to re-distillation. A large proportion 
of the best zinc of commerce, bearing the name 
of spelter, is imported into Britain from Upper 
Silesia, by way of Hamburgh and Belgium. 
Zinc has a brilliant metallic lustre, and a 
bluish-white colour. Its fracture is shining and 
lamellated ; its hardness makes strong resistance 
to the file, yet allows a black stain to be given 
to the human fingers by rubbing; and its specific 
gravity varies from 6'861 to 7:1. At low or ordi- 
nary temperatures, it is brittle, and may be easily 
split or broken by a properly directed blow; at 
any temperature between 212° and 400° Fahren- 
heit, it is so malleable and ductile that it can be 
hammered or rolled into sheets of considerable 
thinness; and at all higher temperatures, it is 
very brittle, and can be pulverized in a mortar. 
Its malleability is considerably diminished by the 
impurities which are naturally combined with it ; 
and is correspondingly increased either by the 
comparative purity of the ores from which it is 
obtained, or by the comparative care and refine- 
ment of the process in which it is separated. 
Zinc fuses at 680° Fahrenheit ; and, when slowly 
cooled, crystallises in four-sided or six-sided 
prisms; and if subjected in close vessels to a 
white heat, it distils over unchanged. “By. ex- 
posure at ordinary temperatures to the action of 
air and moisture, it undergoes little change; but 
by exposure at the temperature of fusion to the 
air, it rapidly oxidizes, and forms the white oxide 
popularly called flowers of zinc; and by similar 
exposure at considerably higher temperatures, 
probably from about 940° upwards, it burns with 
a dazzling white flame, and passes with such vio- 
lence into the state of oxide as to be completely 
volatilized during the combustion. It dissolves 
and oxidizes in all the mineral acids; and, when 
aided by a small portion of sulphuric or of muri- 
atic acid, it decomposes water, and gives off a 
minute portion of its substance into solution with 
the liberated hydrogen. 
Zine is extensively used for making baths, 
water-cisterns, pipes, spouts, filings for fire-works, 
various kinds of plates, voltaic batteries, and 
many varieties of objects for which lead and copper 
were formerly employed. It is used also for cov- 
ering roofs, and for a number of architectural 
purposes; and has been introduced, in various 
ways, to the fitting up and furnishing of the far- 
mery. But though it has the recommendation 
of being but very slightly tarnishable and of 
never accumulating a coat of oxide, it is, in 
many circumstances, a highly objectionable ma- 
terial for pipes and cisterns on account of its 
voltaic action upon water, and for architectural 
purposes on account of its comparatively easy 
and very keen combustibility. Several prepara- 
tions of it are of great service in medicine; and 
three of these are noticed in the articles Cana- 
MINE, WHITE ViTRIoL, and Turry. 
The protoxide or white oxide or flowers of 
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