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western coast belt on Boston Neck and northward to Barber's
Height (Loc. 9, B-C : 12) and in northern Conanicut Island ;
and the fact was explained by the inference that the action of
the maximum component of the forces of deformation was
here predominant. These are also districts of almost uni-
formly high metamorphism.

In the western coast belt between Hamilton (Loc. 8, B : 11)
and East Greenwich, and on Prudence Island, strikes are
somewhat variable. The degree of metamorphism is constant
and is high in these areas.

Elsewhere strikes are less regular and, coincidently, varia-
tions in the metamorphism within short distances are greater.

Tlius, there seems to be a correspondence between the
degree of regularity in the strikes of the major folding, on the
one hand, and the intensity of the metamorphism, on the
other hand.

Dips. — The degree of metamorphism is more often high
than low where dips are steep ; but locally it may be high in
outcrops with a gentle dip.

* This Jonmal, last number, pp. 256-259.



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370 F. H. Lahee — Metamorphimi and Oeological Si/ructute,

PiTOH. — The stage of metamorphism has no bearing upon
the direction of pitch. It is usually high in regions where the
pitch is steep, and may be high where pitch is low.

Axial planes. — The intensity of metamorphism is unre-
lated to the direction of dip of the axial planes.

Relative numbeb of folds across the Basin. — In treating
this subject, we concluded " that the number of principal fol(C
per unit of Basin width, and therefore the degree of compres-
sion, regularly increases southward."* As regards the geo-
graphic distribution of the degrees of metamorphism, we stated
" that the degree of metamorphism in the soutnern half of the
Basin increases westward and southward " (see p. 15). Clearly,
here is concordance of phenomena.

MiNOE FOLDING. — Bclow are listed the localities of contor-
tionf in an order such as to emphasize their positions in the
major folds and to bring out the relations between the degrees
of metamorphism and the amount of contortion :

Stages of metamoT-

Position in Locality Metamorphism pnism in hand- Degree of

fold nnmber in general specimens contortion

Cg. Ss. Sh.

In axial 4 Moderate J Moderate

regions of 16 High CDC Considerable

anticlines 27 " D .. C High

33 Considerable C C C "

Situated on 10 High .. D ._ Considerable

limbs of 14 " .. .. D High

folds 15 " .. D D "

20 " D -. D "
48 « "

Position in 1 High High

folds 5 Slight Slight

uncertain 6 Low .. B A Considerable

n High ..DC

11 " D D ..

12 " .. D ..

13 " .. D .. "

18 " .. .. C

19 " "

21 " "

22 " .. .. D "

25 " "

26 " .. -. D "
29 Considerable "

* See this Journal , last nnmber, p. 259. f Ibid., p. 259.

X Wherever there is no record in this column, the data were obtained in
the field only.



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F. H, Lahee — Metam<ypphi8m and


Geological Structure. 371


30


Moderate




B




Moderate


36


Considerable


..


..


C


Considerable


37


Low


..




A


Moderate


38


Moderate




B




Considerable


40


C(


C


B


B


((


41


a




..


B


Moderate


44


Considerable


C




.


High


49


Variable


_.


C


A


Variable


60


Moderate




B


«.


Moderate



This table indicates a close dependence of the intensity of
metamorphism upon the degree of contortion. Whether the
outcrops are situated on the limbs or in the axial regions of
major folds appears to make no difference.

Relations of the Schistosity to the Bedding.

In a majority of the outcrops examined the schistosity was
nearly, if not quite, parallel to the stratification.* However,
while this is true of the coarser rocks, it does not so often hold
for the pelites. Very notable exceptions are frequent in the
greenish schists of southern Conanicut Island.

Linear schistosity, when well developed, may trend parallel
to the sti'ike of the beds, or parallel to their dip, or in some
other direction. Most often, perhaps, it coincides with the
strike. This relation is not commonly evident in the psammitic
and pelitic rocks on account of their fine texture ; but in the
conglomerates it is easily discerned in the attitude of the
elongated pebbles.f The data obtained in the field work
prove that parallelism with dip or strike is generally in regions
where the strikes are uniform (western coast belt, soutliern
Aquidheck Island), and that departures from this relation are

• CoUie (op. cifc., p. 218) described this for Ck)nanicut Island, and inferred
that the '* schistosity was developed pari passn with the tilting of the rocks,
and that both processes were due to dynamic pressure."

f The lengths of distorted pebbles in metamorphosed conglomerates have
been recorded as parallel to the strike of the beds, by H. H. Rensch (Die
Fossilien Fnhrenden Krystallinischen Schiefer von Bergen in Norwegen.
German translation by R. Baldanf . Leipzig, lb8d. Pp. 52-58) ; Ed. Hitch-
cock (Final Report on the Geology of Mass. Amherst and Northampton,
1841. P. 585; and also. On the Conversion of certain Conglomerates, etc.,
this Journal (2), xxxi, 872. 1861. P. 384); and W. O. Crosby (Contribu-
tions to the Geology of Eastern Mass., Bos. Soc. Nat. His., Occas. Papers,
1880. Pp. 148-149). On the other hand, the case in which the pebbles lie
lengthwise parallel to the dip has been described by Ed. Hitchcock (On the
Conversion of certain Conglomerates, etc. Loc. cit., p. 380); C. H. Hitchcock
(General Report upon the Geology of Maine ; in the Sixth Ann. Rept. of the
Secretary of the Maine Board of Agriculture, 1861. P. 182); and W. P.
Blake (The Plasticity of Pebbles and Rocks : Proo. Am. Assoc. Adv. Soi.,
xviii, p. 199. 1869. P. 201). These differences are caused, no doubt, by
the diversity of orientation of the maximum, intermediate, and minimum
values of complex forces during deformation.



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372 F. H. Lahee-'Metamorphism and Geological Structure.

especially characteristic of districts in which the dips and the
strikes are variable. As illnstrating the latter case may be
mentioned the area north and northeast of Warren Neck, i. e.,
the southern nose of the great Swansea syncline.

On the whole, the attitude of the schistosity in different
portions of the Basin is closely related to the attitude of the
stratification.

Conclusions.

Following are the conclusions arrived at from the study of
the Carboniferous rocks of the Basin :

1. During the period of their deformation, the Carbon-
iferous sediments were deeply buried.

2. On account of the thick cover, or for other reasons,
variations in the decree of metamorphism have been directly
determined neither by alternating differences of texture nor
by relative stratigraphic depth.

3. The degree oi metamorpliism is closely related to the
kind and intensity of the folding, for (a) metamorphism and
compression increase in severity in a southward direction ; (J)
the greatest metamorphism occurs in the region where there
is greatest regularity of strikes ; {c) contortion of the beds is
accompanied by a high degree of metamorphism ; and, {d) the
attitude of the schistosity generally bears a close relation to
the attitude of the bedding.

Cambridge, Mass., Feb. 1, 1912.

(To be concluded.)



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Ch&ini%try and Physics. 373

SCIENTIFIC INTELLIGENCE.

I. Chemistry and Physics.

1. Separation of Titanium from Niobium^ Tantalum,^ Tho-
riumy and Zirconium. — It has been found by J. H. Mitlleb that
salicylic acid shows a different behavior with titanium hydroxide
than with the other " metallic acids." An excess of salicylic acid
added to alkaline niobate or tantalate solutions completely pre-
cipitates the acidMy but the presence of an alkaline nuoride pre-
vents this precipitation. Orthotitanic acid dissolves in salicylic
acid, giving, in the absence of fluorides, an intensely yellow solu-
tion. Zirconium and thorium hvdroxides dissolve with difficulty
in salicylic acid, but after ignition the resulting oxides are prac-
tically insoluble in it.

Known amounts of the oxides of niobium, tantalum, zirconium
and thorium were each mixed with known weights of titanic
oxide, and the mixtures were then fused with 5 grams of potas-
sium carbonate, the fusions were taken up in 350-400^^ of water
at 60° and treated with 14-15 g. of salicylic acid, and heated for
3 or 4 hours at the boiling temperature. Then the precipitates
were allowed to settle, Altered rapidly, and washed with boiling
water. The concentrated filtrates were treated with ammonium
hydroxide, when titanium was precipitated, washed and ignited
to oxide. The precipitates were invariably contaminated with
alkali salicylates which could not be removed by washing. The
ignited oxides were, therefore, fused with potassium bisulphate and
weighed in the usual manner.

The results given from test-analyses show remarkably good
results in the separation of elements which has heretofore been
exceedingly difficult or even impossible in some of the cases.
From the tabular statement of the results it appears that three
or four fusions are necessary with any but very small amounts of
titanic acid, although nothing is said about this point in the
description of the method.

The exceedingly strong color of the salicylic acid solution of
titanic acid was used satisfactorily in determining the titanium in
several mixtures, but the author considers this calorimetric
method as of little practical value, owing to the interference of
the common contaminants of titanic oxide. — Jour. Amer. Chem.
Soc.y xxxiii, 1506. h. l. w.

2. Cementiie. — This important constituent of steels, Fe,C,
which may be called also tri-ferro-carbide, has recently been care-
fully studied by Ruff and Gkrsten with interesting results.
The substance was prepared according to well known principles
by suddenly cooling molten iron saturated with carbon and treat-
ing the pulverized product at first for a long time with dilute
acetic acid, then pulverizing the residue and treating it further



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374 Scientific Intelligence.

with 1/5 normal hydrochloric acid, and finally after removing
material of low specific gravity by stirring and deoantation, wash-
ing with alcohol and ether and drving in a vacuum. The mate-
rial thus prepared appears to have been unusually pure, as it was
crystalline in character, gave analytical results very close to
those required by theory, and contained no graphite. The product
was dark gray with a tint of bronze in some cases, and very
brittle. Some of the larger fragments were used for hardness
determinations with the surprising result that this was found to
bo only just above 3, according to the mineralogical scale. The
conclusion is reached, therefore, that it is not the hardness of the
carbide itself which causes the hardness of suddenly cooled steel,
but that of its solid solution in y-iron.

The authors have determined the heat of combustion of their

Eroduct and have found 375*1 cal. per molecule of Fe,C, when
umt to Fe,0^ and CO,. By comparing this result with their
own determinations of the heat of combustion of pure iron and
the known value for graphitic carbon, they have calculated the
heat of formation as follows :

3Fe-f-C = Fe,C-151 caL

The comi>ound is consequently shown to be endothermic, whereas
previous indirect calculations had indicated an exorthermic com-
oination of + 8940 cal. — Beriehte^ xlv, 63. h. l. w.

3. The Use of Sulphur Monochloride for Decomposing Cer-
tain Minerals, — The process of decomposing various minerals by
means of sulphur monochloride was described by Edgar F. Smith
in 1898. Since that time the method has been applied by various
other chemists. W. B, Hicks, of the University of JPennsyl-
vania, has recently applied this method to the decomposition of
fer^usonite, sBschynite and samarskite, which are rare-earth min-
erals containing colnmbium and tantalum. The process consists
in heating the finely pulverized mineral in a boat in a combustion-
tube in contact with the vapor of sulphur monochloride, with the
result that columbium, tantalum, titanium and tungsten are
volatilized as chlorides and may be collected in nitric acid, while
the rare earths, together with silica, are left behind in the boat.
The method appears to possess advantages over the usual methods
of decomposition by means of fusion with acid potassium sulphate
or the acid fluoride. — Jonr, Amer. Chem. SoCy xxxiii, 1492.

H. L. w.

4. Determination of Water, — ^Zbbbwitinoff has devised a
rapid and accurate method for the determination of water in
various substances, which is interesting on account of being
based on a new principle. He treats the substance, for example
coal or starch, in a special form of apparatus with perfectly dry
pyridine. This liquid is very hygroscopic and, therefore, takes
up the water from the substance. A proper amount of methyl
magnesium iodide in amyl ether solution is then added whereby
methane is liberated, and the volume of this gas is at once meas-



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Chemistry and Physics. 375

ured in the special apparatus, and from this gas volume the
weight of water present is calculated. The reaction taking
place is as follows :

2CH,MgI + H,0 = 2CH, + Mgl, + MgO.

For the preparation of the reagents, which requires special pre-
cautions, as well as for the description of the apparatus, the
measuring part of which is based upon Lunge's nitrometer, refer-
ence must be made to the original article. — Zeitschr. analyt.
Chem,^ li, 680. h. l. w.

5. Reduction of Vanadic Acid in Concentrated Sidphwric Acid
Solution, — Cain and Hostbtteb have found that vanadium pen-
toxide in concentrated sulphuric acid solution is reduced imme-
diately and quantitatively to the quadrivalent condition by
hydrogen peroxide. All that is necessary is to evaporate the
solution until fumes are given off freely, cool, add a slight excess
of 3 per cent hydrogen peroxide, cover the flask and fume strongly
for a few minutes to destroy the excess of hydrogen peroxide,
after which the solution may be titrated with permanganate. It
was found that molybdenum, titanium and iron are not similarly
reduced, and that persulphates and also Caro's acid have the
same effect as hydrogen peroxide upon the vanadium pentoxide. —
Jour, Amer, Chem, SoCy xxxiv, 274. h. l. w.

6. Die Zersetzung von Stickstoffdioxyd im dektrischen Griimni'
Strom, — ^An easily reproducible, beautiful and instructive demon-
stration experiment was performed by J. Zbnneok before the
Physical Section of the 83d Convention of German Scientists at
Karlsruhe, on September 26, 1911. The apparatus was con-
structed of ^lass, and it may be described as follows.

A cylindrical bulb with its long axis vertical was partly filled
w^ith pure nitrogen tetroxide, N,0^, which was maintained in its
more complex molecular condition and liquid state by surround*
ing the bulb with a freezing mixture of ice and common salt. A
horizontal glass tube of convenient diameter connected the top of
the bulb with a discharge tube, to be described later on. The
horizontal tube was drawn down to capillary dimensions not far
from its union with the bulb. Beyond the capillary section this
tube was provided with a glass stopcock. The discharge tube
was shaped like a vertical U, with relatively long " legs" or par-
allel branches which were comparatively close together. Near
the upper end of each leg a short, horizontal section of glass
tubing was sealed in place. These inlet and outlet tubes were at
the same level and both were situated in the plane of the U-tube.
The object of these tubes was to enable the experimenter to con-
nect the discharge tube with the above-mentioned horizontal
tube leading from the bulb, and with the rest of the train of
apparatus, by means of short pieces of rubber " connecting tub-
ing." Above the common level of the horizontal tubes each le^
of the U-tube was sealed to a vertical, cylindrical bulb. Each
bulb contained an electrode whose wire was sealed into the top of



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376 Scientific Intelligence.

the bulb and then continned to one terminal of the secondary of
a spark coil. The primary coil was fed with an alternating
current. Thus the discharge tube was simply a long vacuum
tube bent through 180^ at the middle of its len^h. The outlet
tube was joined to a second discharge tube which was spherical
in form and which was provided with two lateral tubes each con-
taining one electrode. These side tabes were in the same vertical
line and hence at right angles to the several sections of connect-
ing tubing. The inlet and outlet tubes of the spherical discharge
bulb lay along a horizontal diameter, and each was furnished with
a glass stop-cock. The last outlet tube led to a Gaede mercury
pump. Usually the pump was regulated so as to maintain a
pressure of about 1"" of mercury in the region of the inlet of
the H-tube, and this corresponded to a rate of flow of the gas of
about 8 meters per sec, at the same place.

When all three cocks were open and the IJ-tube alone was suit-
ably excited, the following striking phenomena could be observed.
Just below the inlet tube the discharge was yellow with a tinge
of orange, and this was succeeded by a bluish violet region lower
down in the limb. Still further down in this branch and through-
out the entire curved portion of the H a greenish yellow light
was emitted. In the second leg, and immediately below the out-
let tube, the gas radiated bright red. If the electric current was
decreased, while the flow of gas was maintained constant, the
regions of different hues grew appreciably longer. Increasing
the current shortened the colored segments. On the other hand,
when the electrical conditions were kept invariable, the aforesaid
regions increased or decreased in length according as the rate of
flow of gas was made larger or smaller.

That these phenomena are due to successive stages in the dis-
sociation of nitrogen dioxide may be shown by the aid of the
spherical discharge tube. Without exciting either tube, the gas
is drawn slowly through the entire system for some time, and
then the cocks on both sides of the spherical bulb are closed. On
sending the electric current through this bulb the discharge first
assumes a reddish yellow color, which gradually passes over into
bluish violet. Suddenly the color changes to greenish yellow and
this, in turn, slowly gives place to bright red. Thus the various
stages of dissociation which are seen simultaneously, but spread
out linearly, in the U-tube are presented in succession, but in the
same general region, in the closed vacuum bulb.

The question of the physical significance of the various color
changes has been investigated spectroscopically by J. Zenneck
and B. Strasser.* The fii-st spectrum, of orange yellow color,
belongs either to the tetroxide or the dioxide of nitrogen, since
both of these vapors seem to give practically the same radiation.
The second spectrum is due to some " labile" oxide intermediate
between the dioxide and nitric oxide, perhaps nitrogen trioxide.
Nitric oxide gives rise to the third spectrum, while the fourth is

• Phys. ZtBchr., No. 26, p. 1201, Dec., 1911.



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Chemistry and Physics, 377

chiefly due to nitrogen and oxygen gases separately. — Verh. d.
de^Usch. phys. Qesellsch., No. 21, p. 953, 1911. h. s. u.

7. The Mechanism of the Semi-permeable Membranej and a
N(Bto Method of Determining Osmotic Pressure. — Heretofore, the
semi-permeable membranes used in measuring osmotic pressures
had to fulfil the condition of rigidity, either directly or by being
deposited in a rigid support. A very ingenious scheme for abol-
ishing this difficuH requirement has been devised and tested by
F. T. Tbouton. Although the principles involved are of a gen-
eral nature, it will be conducive to clearness to restrict the follow-
ing explanation to a typical case.

Suppose the problem is to find the value of the osmotic pressure
of an aqueous solution of pure sugar of a given concentration.
For theoretical purposes, we may imagine a rectangular glass
vessel, of the type often used in stationary storage cells, separated
into two compartments by a vertical, transverse, impervious
diaphragm, e. ^., a sheet of glass. This diaphragm must not
extend to the level of the top of the vessel. One compartment is
nearly filled with water, and the other with sugar solution.
These liquids are then placed in hydrostatic communication by
having superposed upon their upper surfaces a layer of liquid
ether of sufficient depth to completely submerge the upper edge
of the partition. Since sugar is insoluble in ether, while ether
dissolves a small percentage of water, it follows that the layer of
ether will take the role of the usual effectively rigid, semi-per-
meable membrane. In fact, this is the key-note of Trouton's
innovation, namely, to substitute a liquid semipermeable partition
for a rigid one. To be sure, both water and sugar solution take
up some ether, but this complication is not serious since it can be
relegated to the sphere of determinate corrections. Ether dis-
solves about 1'06 per cent of water when placed in contact with
the same, but ether absorbs less than this from a sugar solution,
the amount depending upon the concentration of the solution.
For equilibrium at the water-ether surface the ether must, there-
fore, contain r06 per cent of water, while at the solution -ether
interface a smaller quantity is necessary to establish equilibrium.
Diffusion through the ether prevents this equilibrium from being
established, consequently, water will pass across from the water
side to the solution side of the partition. If the ether could rig-
idly maintain its position so as to prevent any increase in the
volume of the sugar solution, the hydrostatic pressure of this
solution would increase, due to the accession of water. Under
these ideal circumstances the process would come to an end when,
owing to the increase of pressure, the percentage of water
absorbed by the ether from the sugar solution attained the same
value as the fraction of pure water taken up by the ether at
atmospheric pressure. The pressure competent to effect this
state of equilibrium in the ether would be the equivalent of the
osmotic pressure of the sugar solution.

Am. Jour. Sci. —Fourth Series, Vol. XXXJII, No. 196.— April, 1912.
25



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378 Scientijio Intelligence.

Effective rigidity can be imparted to the ether by the apparatus
designed by Trouton and used by Burgess. It consisted of a
vertical, copper U-tube strong enough to withstand an internal
pressure of more than loO atmospheres in excess over the outside
atmosphenc pressure. One of the parallel branches of the tube
was permanently connected with a pressure gauge, and the upper
ends of both branches were provided with stopcocks and inlet
tubes. In charging the apparatus the first step was to introduce
enough sugar solution to half-fill the tube. Then ether was
sucked into the branch which was not directly associated with
the gauge, and the cock closed. Next, air was pumped into the
other branch of the U-tube until the gauge registered the desired
pressure, after which the second cock was closed. After sufficient
time had elapsed for the ether to take up its full complement of
water from the solution, the cock of the branch containing the
ether was opened, thus allowing the compressed air in the other
branch to force the ether out into the auxiliary testing tubes.
The water content of the ether was determined by passmg the
moist ether, as vapor, through calcium chloride drying tubes
which were maintained at 40° C. " This was sufficiently warm
to prevent ether condensing in the tubes, and yet was found not
to be too high for substantially absorbing all the water." This
entire process was repeated at different pressures, so that all the
necessary data were obtained for plotting a curve having for the
abscissas of its points, pressures in atmospheres, and for the ordi-
nates, percentages of water absorbed by the ether. For a con-
centration of 600 grams of sugar per liter of solution the aforesaid
percentages increased from 0*939 to 1*143 as the pressure changed
from 1 atmosphere to 110*5 atmospheres. The curve is somewhat
convex towards the pressure axis. At about 79 atmospheres the
per cent of water taken from the sugar solution by the ether was



Online LibraryJohn Elihu HallThe American journal of science → online text (page 37 of 61)