Virginia citizen. (Irvington, Va.) 1891-1921, 1905-12-22
METALLIC TANTAlUM.
O SupcrsedeS the Diamond az tn
Hardest known Substance

~ SupersedeS the Diamond az the
Hardest known Substance. rr
For centuries the diamond has been
recognized as the hardest of all known
substances. The polish power OF dia-
mond dust and the boring power of the
diamond drill are familiar facts. SO
Is the fact that nothing can polish or
cut diamond except another diamond.
But n new substance has made Its ap-
pearance which. il 1t can be obtained
in sufficient quantity, VIII probably re-
place the diamond alike In the opera
lions OF drill boring and In the lapi-
dary's workshop, for 1t Is harder than
dlamond-so hard, in fact. that the only
effect produced by n diamond drill
worked day and night for three days
on sheet of the substance one twenty
fifth Of an inch thick, with a speed OF
5000 revolutions per. minute, was a
slight dent In the sheet and the wearing
out OF the diamond. This substance IL
pure metallic tantalum.
.Tentsiua Is not a eomnon metal,
yet IL is also not one of the rarest. Its
existence was discovered more than a
century ago, but no attempt to separate
1t from It's compounds had succeeded
prior to 1905, when Melssan obtained
sample In the electric furnace. The
metal which he isolated was very hard
and brittle, and We now know that IL
was SO much contaminated with car
bon that most of the characteristic
properties OF the pure metal had dis
appeared. se.el ..I. so, I.
Pure tantalum was first prepared by
Or. Bolton, member of the famous
electrical engineering firm OF Siemens
K Halske. One OF his methods is TO
fuse the double huoride Of potassium
and tanta1um with metallic potassium
in an electric furnace in vacuo, but he
seems to prefer much simpler cleo
trical method. Making up the oxide
into a filament exactly like thar, OF
n Nernst incandescent lamp, he places
II in globe connected to an air pump
AMI turns on the current. The oxide
Is decomposed, and, the oxygen being
gradually removed by the pump, the
hlament Is reduced TO the metallic
state. 49, a-''
Tantalum differs from all other known
substances In combining extreme hard
ness with extreme -ductility- OF its
hsrdness we have, already given an en-.
ample. 30 need only add that When red
bot 1t Is easily rolled into bars, and
sheets or drawn into wire IT Is scarce
ly affected by the oxygen, of the atr
even at n red heat and not at ali at
ordinary temperatures, and the strong
est acids fail TO dissolve 10. Nor does
1t amalgamate with mercury. 1t pelts
only ut the highest iattainable temper
atures and is therefore well fitted to
serve for filaments I'm incandescent
lamps, being much stronger than car.
bon A pound OF Il will make 10000
lamps, and these require exactly half
as much power 10 light them as do
carbon filaments giving the same bril-
lIancy. li NHf fTF0u ugIU
III only IL can be procured In sufficient
quantity tantalum should prove n most
useful metal. 1t will furnish better
boring tools than the diamond drill
and cheaper electric lights than car
bon. while the possible uses OF u plate
or n wire harder than diamond and vet
tough and strong are almost Infinite.
for every other hard substance is brit.
tie. and this fact has hampered the en-
gineer for centurles.-New York Her.
aid . .. ...... m. |