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the formation of traces of nitric acid from the spontaneous decom-
position of the free nitrous acid. The hydrazine method has the
advantage that the nitrous acid does not need to be set free by
another acid, since the sulphuric acid combined with the hydra-
sine furnishes sufiicient acid for the decomposition of the nitrite,
and moreover the reaction goes so rapidly that no nitric acid can

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500 Scientific Intelligence,

be formed. Experiments with pure sodium nitrite showed that
there was no odor of nitrous gases in the nitrogen escaping from
the reaction with hydrazine sulphate, and that the solution after
the reaction was complete gave no test for nitric acid with diphe-
nylamine in concentrated sulphuric acid. — 2kit8c/ir, anorgan.
Uhem.^ Ixxiv, 52. h. l. w.

3. The Chemical Constitution of Ilmenite. — W. Manchot has
made analyses of a massive titanic iron ore from Ekersund in
Norway and a crystal of ilmenite from the Urals. The results iu
the two analyses are very dissimilar, and the ilmenite analysis is
incomplete, but the latter is of some interest because the ferric
oxide was determined by dissolving the substance, out of contact
with air, in hydrochloric acid and using iodimetry. This deter-
mination indicates that the ratio of TiO, to F^eO approaches 1 : 1.
This is used as an argument in favor of the ilmenite formula
TiO,.FeO, and in opposition to the view that it is a mixture of
Ti,0, and Fe,0,. It appears that the same formula was indi-
cated much more satisfactorily by the work of Penfield and Foote
(this Journal, iv, 108, 1897). The author has attempted to show
by direct experiment that Ti,0, is not contained in the mineral
by demonstrating that the powdered samples when boiled either
with alkalies or acids evolve no hydrogen gas. Although the
author considers these experiments to be conclusive, it does not
appear that this is the case, for if a titanous salt and a ferric salt
were formed at the same time it is perfectly well known that, at
least in acid solution, the ferric salt would be reduced, and if the
ferric salt were in excess no hydrogen could possibly be given off.
In the case of alkalies, if any reaction at all occurred, it might
happen that nascent hydrogen would reduce ferric oxide instead
of forming a. gas. — Zeitachr. anorgan. Chem,^ Ixxiv, T9.

H. L. w.

4. Determination of Alkalies in Silicates, — For this determi-
nation E. Ma^inen has used fusion with about 10 parts of cal-
cium chloride in the place of J. Lawrence Smith's method. The
platinum crucible in which the fusion is made is placed in a hole
in a piece of asbestos board in such a way that only the lower half
of the crucible comes in contact with the flame. This part of the
crucible is gradually brought to a full red heat by means of a
Teclii burner, and so maintained for 25 or 30 minutes. The
treatment is then similar to that usually employed in Smith's
method. Specially prepared calcium chloride was required, as
the commercial product was found to contain alkalies. The
results with several feldspars and rocks were good, but it appears
to the reviewer that, on account of the very large amount of cal-
cium chloride going into solution, which necessitates a double
precipitation of calcium carbonate, the process will not replace
the usual one. — Zeitschr. anorgan, Chem., Ixxiv, 74. h. l. w.

5. A Dictionarp of Applied Chemistry ; by Sir Edward
Thorpe, C.B., LL.J)., F.R.S., assisted by Eminent Contributors.
Revised and Enlarged Edition in Five Volumes. Volume I (A- ^

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Cliemiatry and Physics, 501

CHEJ. 8vo, pp. 758 ; London, 1912 (Longmans, Green and Co.).
— Twenty-two years have elapsed since the first edition of this
well-known book of reference made its appearance as a companion
to Watts' Dictionary. During this period chemistry has advanced
to such an extent in its applications to the arts and manufactures
that a complete revision and a great enlargement of scope in
the present edition have been necessary. It will consist of five
volumes in the place of the original three volumes.

An inspection of the new volume shows evidence of thorough
work on the part of the contributors, who have been selected not
only from the United Kingdom but also from America, Germany,
Switzerland, etc. The work appears to have been thoroughly
revised and modernized, particularly as far as the topics in which
great advances have been made in the last two decades are con-
cerned. No detailed review of a book of such magnitude and
complexity can be attempted here, but a few of the prominent and
interesting articles in the present volume may be mentioned, such
as ** Acetylene as an Illuminant," "Analysis," "Aluminium,"
" Brewing," " Carbohydrates," and " Cellulose." h. l. w.

6. On the Properties of the Mays Produci7ig Aurora Borealis,
—It has been generally assumed that aurorae are caused by elec-
tromagnetic disturbances in the earth's atmosphere due to radia-
tions from the sun, but the precise nature of these radiations has
not been established heretofore. An appreciable advance towards
the solution of the problem has been made by L. Vegard, who
starts with the hypothesis that the incident radiations are small
electrified particles or rays. The straight-lined streamers of the
aurorffi would require a radiation which is but little scattered and
this condition is fulfilled by a-rays and not by /8-rays. The
abruptness with which the luminosity stops at the lower edges of
the streamers corresponds to the well-defined range of a-particles
in a gas. The ionization, due to a homogeneous pencil of a-rays,
is known to increase as the speed decreases, attaining a maximum
value near the point where the rays are stopped. This fact has
its counterpart in the increase in luminosity observed near the
lowest paits of auroral bands and streamers. By comparing the
altitudes at which the a-rays from various radio-active substances
would be stopped by the earth's atmosphere with the observed
heights of aurorae, Vegard shows that the agreement is as good
as can be expected from the data at hand. The parallel, drapery
bands can be accounted for by the assumption of groups of homo-
geneous rays from the same source. A mathematical investiga-
tion of the paths which would be followed by charged particles
entering the earth's atmosphere from the sun, leads to the conclu-
sion that a positive charge is most consistent with the observed
positions of aurorae. Thus it is seen, that the majority of auroral
iporms majr be explained on the assumption that they are due to
a-rays emitted by radio-active substances of the sun. — PhiL Mag,y
xxiii, p. 211, February, 1912. h. s. u.

7. The Pressure of a Blow, — In a discourse delivered at the
Royal Institution on January 26, Prof. Bertram Hopkinson

Am. Jour. Sci.— Fourth Series, Vol. XXXIII, No. 197.— May, 1912.

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502 Scientific Intelligence,

gave sonie very striking figures and described some highly inter-
esting phenomena associated trith blows produced in various
ways. An account of only a few typical cases may be here pre-

Suppose that each of two equal billiard balls has a speed of
eight feet per second and that they are moving towards each
other along their line of centers. At the very instant of touch-
ing there is, of course, no pressure between the balls, but as tbt?
centers continue to approach, each sphere becomes flattened at.
the region of contact. This region is circular and it rapidljr
increases in area until the balls as wholes are brought to rest, that
is, until the work done against the elastic forces of restitution is
equal to the original kinetic energy of the system. For the case
in question the distance of approach is 14/1000 of an inch and
the force equals 1,300 lbs. The circle of contact has a diameter
of one-sixth of an inch, so that the average pressure amounts to
27 tons per square inch. The distribution of pressure, however,
is not uniform, the pressure at the center of the areas of contact
being 11/2 times as great as the average pressure. The subse-
quent behavior of the spheres is of no interest in this connec-
tion. If very hard, hollow steel balls, having the same mass as
the ivory spheres, are caused to collide with a relative speed of
16 feet per second, the distance of approach will be less, the area
of contact smaller, and the maximum pressure much greater than
for the bUliard balls. This pressure when averaged over the
circle of contact attains a value of 280 tons per square inch.
These results of theoretical computation for steel balls have been
verihed by comparing the calculated time of contact with the
interval obtained experimentally by the aid of appropriate elec-
trical apparatus. The time of contact for the ivory spheres, men-
tioned above, was 1/4000 of a second.

A case involving an inelastic substance is afforded by the
impact of an elongated lead rifle bullet against a hard steel plate.
Under the enormous pressures developed lead flows very freely,
so that, in the absence of any lateral support, each cross-sectional
disc of the bullet maintains its speed practically unchanged until
it comes in direct contact with the steel. The pressure exerted
by the bullet is, probably, sensibly constant, smce it depends
upon the square of the speed, but not upon the length or diam-
eter of the projectile. Increase in diameter only alters the area
over which the force is applied, and increase in length the time
during which it acts. As a practical example, consider a Lee-
Metford bullet moving with the normal speed of 1,800 feet per
second. This projectile is 1 1/4 inches in length, it has a mass
of about 0-03 lb., and it would be stopped in 1 / 18000 of a second.
The force required to destroy the 17 Ib.-second units of momentum
would be 15 tons. Since the area of cross-section of the bullet
ii3 1/14 of a square inch, the mean pressure would amount to 210
tons per square inch.

Passing over several interesting cases involving the propaga-

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Chemistry and Physics. 503

tion of longitudinal waves along steel rods, we shall now consider
very briefly some entirely new investigations made by Hopkinson
on the effects produced by detonating small cylinders of gun-
cotton in contact with steel plates. The gun-cotton is converted
into gas at small volume, high temperature, and enormous pres-
sure, in roughly three or four millionths of a second. The only
thing which restrains the expansion of the gas is the inertia of
the surrounding air, and the pressure accordingly drops with very
great rapidity. It is estimated that the pressure falls from 120
tons per square inch to atmospheric value in about 1 / 26000 of a
second. The same pressure is, of course, exerted by the gas upon
any rigid surface with which the gun-cotton is in contact, and the
force so produced has the characteristics of a blow, namely, great
intensity and short duration. If a cylinder of gun-cotton weigh-
ing one or two ounces is placed in contact with a plate of mild
steel one half an inch thick, or less, and if the explosive is then
detonated, the effect will be to punch a clean hole through the
plate, of approximately the same diameter as that of the cylinder
of gun-cotton, just as if a projectile had passed through the plate.
On the other hand, if the steel plate had a thickness of three-
quarters of an inch, a very curious result would be obtained. A
depression would be formed on the side of the plate next to the
explosive, while a disc of steel of corresponding diameter would
be torn off from the opposite face of the plate and projected with
very high speed. The speed, in fact, corresponds to a large frac-
tion of the whole momentum of the blow. By detonating a two-
ounce cylinder of gun-cotton in contact with a still thicker plate
of steel, a depression and a complementary bulge were produced
on the respective faces of the plate. When the plate was sawed
in two in a plane containing the centers of the dent and of the
lump, the presence of an internal crack was brought to light,
thus showing the beginning of that separation which was com-
plete in the case of the plate three quarters of an inch thick. All
of these phenomena can be accounted for by simple mechanical
principles involving the reflection of longitudinal or sound waves
in the metal.

In conclusion, a few words with regard to the behavior of large
projectiles and armor-plate may not be without interest. Modern
shells are made of a special steel of great strength and consider-
able ductility, the region of the point only being subsequently
hardened by thermal treatment. When a shell of this construc-
tion strikes normally against a plate of wrought iron, or even
mild steel, it ploughs straight through the plate, pushes a plug of
metal before it, and emerges unscathed. A rim or lip is formed
on the incidence face of the plate, which is analogous to the rim
arising when a hole is blown in a lead plate by means of a gun-
cotton primer. To bring a 14-inch shell, having a speed of 2,000
feet per second, to "rest would require at least 2-5 feet of wrought
iron. Modern armor plate is made as hard as possible on the
outside surface, the back being left tough and ductile. When a

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504 Scientific Intelligence.

shell with a hard point is incideot normally on such armor, both
the projectile and the plate are seriously damaged, but the former
does not penetrate the latter. Even when a thinner plate is
pierced by the shell the projectile is usually smashed to pieces in
the act. To overcome this lack of penetrating power it has
become the custom, in recent years, to provide the point of the
shell with a cap of soft steel. In this event, the projectile
punches a clean hole both in its cap and through the armor plate.
In some instances the shell is so nearly intact as to admit of its
being used over again. The cap seems to form a ring around the
nose of the shell at just the right instant, preventing any lateral
deformation or flow of the tip, thus concentrating-the blow over
a small area and enabling the projectile to pierce the armor. —
Nature^ February 16, 1912, p. 531. h. s. u.

8. A Photographic Study of Vortex Rings in Liquids. —
For purposes of demonstration, vortex rings are usually made
in air bv sending puffs of smoke through a circular opening in the
front of a suitable box. It has been shown quite recently, how-
ever, by Edwin F. Northuup that more beautiful and instructive
results can be obtained by using liquids of small viscosity instead
of air. The essential parts of the apparatus used and a few of
the phenqmena produced may be briefly described as follows :

The rectangular experimental tank was chieflj'^ made of plate
glass and its length, depth, and width w^ere respectively 15P°^,
59*5*^", and 12*=™. The vortex rings were projected by means of
a cylindrical can or "gun" 7-Vcm j^ diameter and b-6^™ axial
length. One end of this can consisted of a flexible diaphragm
of phosphor bronze which could be given an impulse by the
plunger of an electromagnet. The muzzle end of the gun was
partly closed by any one of a set of metal discs which contained
one or more holes of various shapes and dimensions. A circular
hole 1*"* in diameter and at the center of the disc was usually
employed to produce single vortex rings. To produce double
rings two holes each of 0*85*^™ diameter were provided with their
centers at a distance of 1*275*^" from the axis of the cylinder. The
tank was generally filled with slightly acidulated water whereas
the can contained strongly alkaline water which was deeply
colored with phenol phthale'in. By this scheme the necessity of
refilling the tank after one or two "shots" was avoided because
the deep red vortex rings disappeared completely as soon as they
lost their form and became dispersed.

Before investigating photographically the behavior of the rings,
Northrup observed the following noteworthy properties of the
vortices. The speed of the rings was initially about two meters
per second and, when free to do so, they moved in straight lines
with their planes perpendicular to the direction of propagation.
They did not appropriate suspended particles of slightly greater
density than the medium in which they moved. When a tightly -
stretched sheet of chiffon cloth was interposed in the path of the
vortex, the ring would pass through the net without being

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Chemist/ry and Physics. 605

destroyed or greatly retarded. In fact, a ring would break
through a sheet of tissue paper, but it would be scattered by the
impact. Also, a light watch-chain would be bent into a decided
curve by a square blow of a ving, hence the kinetic energy of the
rings was quite appreciable. When two rings were sent simul-
taneously from opposite ends of the tank they would be destroyed
if their lines of propagation coincided exactly, but they would
separate and avoid one another if they were so aimed as to bring
their edges into contact if the rectilinear motion persisted. Inter-
nal reflection at the free surface of the acidulated water took place
in a beautiful manner when the angle of incidence exceeded about
6B°. As the surface of the water was approached the upper edge of
the ring would gain in speed as compared with the lower edge
and the plane of the vortex would tilt in such a manner as to
maintain itself always normal to the direction of propagation.
For smaller angles of incidence than the critical angle the ring
would burst through the surface with a spurt of water. Refrac-
tion was also shown by filling the lower half of the tank with a
concentrated salt solution, and the upper half with pure water.
Vortex rings issuing from a truly circular hole do not vibrate,
but rings projected from an elliptical opening exhibit a vibratory
motion in their own plane. These vibrations are very rapid and
consist in changing from ellipses with vertical major axes to
ellipses with the longer axis horizontal.

Most interesting results were obtained with two circular holes
in the muzzle disc of the gun. " The two rings, which issue simul-
taneously from the two holes, begin to attract each other the
moment they leave the gun, and at a distance from the gun of
about 6 to 8*^™ they come together with great suddenness, uniting
to form a single ring of approximately twice the circumference
of one of them." The rings thus formed proceed with the same
speed as a single ring, but the vibratory motions are rather com-
plicated. The component vibrations can only be fully appreciated
by reference to the reproductions of the stereoscopic photographs
in which the original paper abounds.

Experiments were performed which showed that, in the case
of two non-miscible liquids of different densities, it is possible to
project a vortex of the less dense liquid through the medium of
greater density, but it is not possible to reverse the process. For
example, a ring of kerosene oil can be projected through water,
but a vortex of carbon tetrachloride cannot. By projecting rings
of liquid paraflin through hot water and thence into a substratum
of cold water, very pretty solid rings of paraffin were obtained
and preserved.

The diiiiculties attendant upon photographing the vibrating
rings were comparatively great and the requisite assemblage of
apparatus was too complicated to admit of description in this
place. Suflice it to say that full details of the experimental pro-
cesses together with a relatively large number of photographic
reproductions are given in the September and October numbers
(1911) of the Journal of the Franklin Institute. — JSTature, Feb-
ruary 1, 1912, p. 463. H. s. u.

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Scientific Intelligence:

9. Note on Nevil Maskelyne^s Article, " On the Trisection of
an Angle^"* ; by H. S. Uhleb (communicated).— -In the Philo-
sophical Magazine for April, 1912, a geometrical construction is
given by Maskelyne, on page 647, which he states will trisect any
angle. This claim is surprising because the construction is not .
qualified as an approximation and also because no proof is sug-
gested in the article. It is the purpose of the writer to show that
the aforesaid construction is not valid. To accomplish this, it is
sufficient to prove that a right angle will not be trisected in the
manner indicated by Maskelyne.

In the accompanying figure the letters have the same signifi-
cance as in the original article.

Let = af = fd =z db = ag = ge = ec = 1 .

From the right triangle caf, cf = \/\0,

Since ah bisects Z cab, ch = ^cf = ^ VlO.

ah* = a<i' + cA" — 2ac. eh. cos (lacf) = | = ak\

Considering ac and ab as axes of x and y respectively, it

follows that the equation of the line <^/' is a; 4- 2 y — 2 = 0,

and of the circle J K, 8 a" -f 8 y' — 9 = 0. Consequently the

.. ,. , - , /\/'26 + 4 16->^26\

coordinates of k are I- -, ^ — )•

\ 10 ' 20 /

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Geology. 507

Hence, tan (Leak) = — tYI. == ^26 — 4-6 — 0-699019
2^/26 + 8
and JLcak == 30** 66' 21*.

Therefore, in this special case, the error amounts to nearly one
degree. It maj be remarked, in conclusion, that we have worked
out an analytical expression, for the general case, connecting
Leak with Lcab and found that this function is not satisfied by
putting Lcab = S(Lcak).

II. Geologt.

1. Publications of the United States Geological Survey;
George Otis Smith, Director. — Recent publications of the U. S.
Geological Survey are noted in the following list (continued from
p. 62, Jan., 1912) :

Topographic Atlas. — Sixty-five sheets.

Folios. — No. 17b. Foxburg-Clarion Folio, Pennsylvania ; by
E. W. Shaw and J. M. Munn. Pp. 17 ; columnar section, 4
topographic and geologic maps.

No. 179. Pawpaw-Hancock Folio. Maryland- West Virginia-
Pennsylvania ; by George W. Stose and Charles K. Swartz.
Pp. 24 ; 3 topographic and geologic maps ; 20 half tone views.

No. 180. Claysville Folio, Pennsylvania ; by M. J. Munn.
Pp. 14 ; sections, 4 topographic and geologic maps. 10 figures.

No. 181. Bismarck Folio, North Dakota ; by A. G. Leonard.
Pp. 8 ; 1 topographic, 1 geologic map.

Mineral Resources of the United States. Calendar year
1910. Part I.— Metals. Pp. 796 ; 1 plate, 9 figures. Part II.—
Nonmetals. Pp. 1006 ; 17 plates, 10 figures. The individual
chapters of this invaluable compilation have already been issued
in advance.

Bulletins. — No. 470. Contributions to Economic Geology
(Short Papers and Preliminary Reports), 1910. Part I. — Metals
and Nonmetals except Fuels. C. W. Hayes and Waldemar
Lindgren, Geologists in Charge. Pp. 668 ; 17 plates, 64 figures.

No. 485. A Geologic Reconnaissance of the Iliamna Ret^ion,
Alaska ; by G. C. Martin and F. J. Katz. Pp. 138 ; 9 plates,
20 figures.

No. 493. Results of Spirit Leveling in Illinois, 1909, 1910 ; R.
B. Marshall, Chief Geographer. Pp. 115 ; 1 plate.

No. 494. The New Madrid Earthquake ; by Myron L.
Fuller. Pp. 119 ; 10 plates, 18 figures.

No 496. Results of Triangulation and Primary Traverse for
the Years 1909 and 1910. R. B. Marshall. Chief Geographer.
Pp. 392 ; 2 plates.

No. 497. A Reconnaissance of the Jarbridge, Contact, and
Elk Mountain Mining Districts, Elko County, Nevada ; by F. C.
ScHRADER. Pp. 162 ; 26 plates, 3 figures.

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508 Scientific Intelligence.

No. 499. Coal Near the Black Hills, Wyoming-South
Dakota ; by R. W. Stonk. Pp. 66 ; 7 plates, 8 figures.

No. 500. Geology and Coal Fields of the Lower Matanuska
Valley, Alaska ; by Q. C. Martin and F. J. Katz. Pp. 98 ; 19
plates, 12 figures.

No. 604. The Sitka Mining District, Alaska ; by Adolph
Knopf. Pp. 32 ; 1 plate, 4 figures.

No. 505. Mining Laws of Australia and New Zealand ; by
Arthur C. Veatch with a preface by Walter L. Fisher. Pp.

No. 511. Alunite: a newly discovered deposit near Marysvale,
Utah ; by B. S. Butler and H. S. Gale. Pp. 64 ; 3 plates.
This new locality for alunite gives promise of affording a consid-
erable amount of the potash so much needed in this country.

Water-Supply Papers. — No. 280. Gaging Stations maintained
by the TJ. S. Geological Survey, 1888-1910, and Survey Publica-
tions relating to Water Resources; compiled by B. D. Wood.
Pp. 102.

Nos. 282, 286, 287. Surface Water Supply of the United
States, 1910 ; prepared under the direction of M. O. Lbighton.
No. 282. Part II. South Atlantic Coast and Eastern Gulf of
Mexico; by M. R. Hall and J. G. Mathers. Pp. 109; 3 plates.

Online LibraryJohn Elihu HallThe American journal of science → online text (page 50 of 61)