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Tantalum : Ta | |||
Tantalum is also used to produce a variety of alloys that have high melting points, are strong and have good ductility. Alloyed with other metals, it is also used in making carbide tools for metalworking equipment and in the production of superalloys[?] for jet engine components, chemical process equipment, nuclear reactors, and missile parts. It is ductile and can be drawn into fine wire, which is used as a filament for evaporating metals such as aluminum.
Because it is totally immune to the action of body liquids and is nonirritating it is widely used in making surgical appliances. Tantalum oxide is to make special high index of refraction glass for camera lenses. The metal is also used to make vacuum furnace[?] parts.
Its name is derived from the character Tantalus, father of Niobe in Greek mythology, who was punished after death by being condemned to stand knee-deep in water with perfect fruit growing above his head, both of which eternally tantalized him - if he bent to drink the water, it drained below the level he could reach, and if he reached for the fruit, the branches moved out of his grasp. This was considered similar to tantalum's general non-reactivity - it sits among reagents and is unaffected by them.
Tantalum ores are mined in Australia, Brazil, Canada, the Democratic Republic of the Congo, Mozambique, Nigeria, Portugal, and Thailand.
Tantalite is largely found mixed with columbite in an ore called coltan, about whose sources ethical questions have been raised (see the article).
Several complicated steps are involved in the separation of tantalum from niobium. Commercially production of this element can follow one of several different methods which includes; electrolysis of molten potassium fluorotantalate, reduction of potassium fluorotantalate with sodium, or by reacting tantalum carbide with tantalum oxide. Tantalum is also a byproduct from tin extraction.
all of which are labelled.
"You will please deposit the boxes, fifty in number, which form
part of the house.html">house and marked `A' on rough diagrams enclosed.
chapel of the mansion. The goods leave.html">leave by the train at 9:30 tonight,
As our client wishes the delivery made as soon as possible,
the time named and forthwith conveying the goods to destination.
requirements as to payment in your departments, we enclose cheque
Should the charge be less than this amount, you can return balance,
from you. You are to leave the keys on coming away in the main.html">main hall
the house by means of his duplicate key.
"Pray do not take us as exceeding the bounds of business courtesy
LETTER, MESSRS. CARTER, PATERSON & CO., LONDON, TO MESSRS.
1 pound, 17s, 9d, amount of overplus, as shown in receipted account herewith.
in parcel in main hall, as directed.
"We are, dear Sirs, "Yours respectfully, "Pro CARTER, PATERSON & CO."
18 August.--I am happy today, and write sitting on the seat.html">seat
she slept well all night.html">night, and did not disturb me once.
The roses seem coming back already to her cheeks,
in any way anemic I could understand it, but she is not.
All the morbid reticence seems to have passed from her,
of that night, and that it was here, on this very seat,
on the stone slab and said,
"My poor little feet didn't make much noise then!
because I didn't want to wake up Geordie."
As she was in such a communicative humour, I asked her if she
her forehead, which Arthur, I call him Arthur from her habit,
Then she went on in a half-dreaming kind of way, as if trying
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