Review of Dental Literature and Art. [Volume: 2, Issue: 10, May, 1861, pp. 562-568]

REVIEW OF DENTAL LITERATURE AND ART.

565

turned, which will enable parties using them to turn the face of the wheel
to conform to work of any irregular shape, or to 'true' them, if necessary."
A combination of corundum and hard rubber, such as that described
above, we have reason to believe would prove quite as useful and far more
durable for grinding porcelain teeth, than the ordinary preparation of
corundum and gum shelac, which wears away so rapidly by use that it
becomes quite an item in procuring materials for the laboratory where
there is much mechanical work to do. It could also be used, no doubt,
for dressing down plates, as the wheels can be adapted to work of an
irregular shape. The suggestion is worth trying, and we trust that those
who are engaged in mechanical dentistry will test the matter.
" ON TUNGSTEN STEEL.-It is stated that cast-iron containing from five
to six per cent. of tungsten acquires an extraordinary hardness. Caststeel, also, containing from four to five per cent. of tungsten, will have a
tenacity and quality superior to those of the best steels, and will become
capable of taking a most extraordinary temper and hardness. According
to trials made at Newstadt, tools of tempered tungsten steel were capable
of cutting objects made of ordinary cast-steel equally tempered.
" Tungsten has nearly the same specific gravity as gold, and this density
is recognizable in the cast-steel alloyed with it, by the alteration in the
grain of the fractured surface, and by the heightened ring of the steel.
In hardness, metallic tungsten nearly approaches the hardest of natural
bodies, and it communicates this property to cast-steel without injuring
its tenacity and malleability when the addition is of 2'5 per cent. The
absolute solidity of tungsten steel exceeds that of all other known steels;
for fifteen consecutive experiments with a machine in the Polytechnic Institute of Vienna showed the highest power of resistance to be 1393 hundredweight, and the lowest 1015 hundredweight, giving an average of
1158 hundredweight to the square inch; so that this steel exceeds all other
kinds hitherto subjected to experiment.
"For the preparation of this steel wolfram (tungstate of iron and
manganese) is purified by roasting, pulverizing, and washing, and by a
final treatment with dilute hydrochloric acid. The purified ore is then
placed in a crucible with coal dust, and heated to redness for three hours.
The ore is reduced, and a porous gray mass is obtained, formed of metallic
tungsten alloyed with carburets of iron and manganese. This is the product which is used for the preparation of tungsten steel, and it is thrown
into the crucibles in which cast-steel is melted. Care must be taken before
running the steel into ingots to increase the heat of the fire, for ten or
twenty minutes, so as to carry the temperature of the crucible to a bright
redness. It appears, however, that the manufacture of tungsten steel in
quantity yet presents considerable difficulties, and that it has not yet been
practicable to prepare masses or bars of considerable size which are free
from faults."
"INFLUENCE OF THE PRESENCE OP TITANIUM ON THE QUALITY OF
IRON.-Mr.David Mushet, the well-known English iron manufacturer, in
a communication to the London Engineer Journal, expresses an opinion
that the mystery of the excellence of the Danemora and other irons is due
to the presence in the iron of a small proportion of the metal titanium.
Some time ago, his attention having been drawn to this matter by the fact