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JOURNAL

OF THE

Elisha Mitchell Scientific Society

VOL, XIII
1896

CHAPEL HILL, N. O.
PUBLISHED BY THE UNIVERSITY

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VTISARVIMU ART Ta GHHeL{aUa

Journal of the Mitchell Society.

CONTENTS.
VOL. XIII.
1896.
A Study of the Zirconates.—F. P. Venable and Thomas Clarke.............. 1
River Adjustments in N: O.—W. J. Weaver ..u....ccccccccceccccccecscccceceescces 13

Reduction of Concentrated Sulphuric Acid by Copper.—Chas. Bask-

SOMME OE coe ON ge ator Neel dite Ua hee Re as sols dy Wo Sean dscslowas v2 dete bade stn een mee 24
The Use of the Periodic Law in Teaching.—F. P. Venable.........-2....... 30
The Present Position of the Periodic System.—F’. P. Venable............... 1

Notes on the Exact Composition of the Queen Part Truss.—W. Cain..... 48

Some Late Views of the So-Called Tocanic and Huronian Rocks in
Central Ol EF O Mie iit Se a eee ga

2TMRTVIOO

Lhe - WO¥

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JOURNAL

OF THE

Elisha Mitchell Scientific Society

VOLUME{XIII—PART FIRST:

JANUARY--JUNE

1896

POST-OFFICE :
CHAPEL HILL, N. C:

ISSUED FROM THE UNIVERSITY PRESSES
CHAPEL HILL, N. C.
1897.

F.P. Venable and Thoitixe Clarke.

a

| River Adjustments in N.C. W. J. ‘Weaver... Le
_ Reduction of Concentrated Sulphuric Acid by Copper. Charles ] :

SOV US 4135 ae As UT at Pa Sat Rk eo

The Use of the Periodic Law ae Teaching. “#R, P. Venable... Ey

+4

JOURNAL

OF THE

Flisha Mitchell Scientific Society.

[CONTRIBUTIONS TO THE CHEMISTRY OF ZIRCONIUM. NO. 5.]

A STUDY OF THE ZIRCONATES.

By F. P. VENABLE AND THOMAS CLARKE.

This class of compounds of zirconium has received but
little attention from chemists, ‘The chief investigator in
the past who has worked in this field was Hiortdahl.!
Of recent years several papers by L. Ouvrard’ have ap-
peared. The accounts given in the various text books of
these zirconates are based upon the work of Hiortdahl or
upon such abstracts of it as were to be found in the Jah-
resberichte, or in such dictionaries as that of Watts.
This is unfortunate, as to the best of our knowledge the
work of Hiortdahl itself is in some respects inaccurate
and erroneous, and the abstracts of it are misleading.
Before giving an account of our own experiments, it may
be well to gather together the statements regarding these
bodies :s given by Watts and in the original article of
Hiortdahl.

Watts says that the compounds of zirconia with the
stronger bases are obtained by precipitating a zirconium
salt with potash or soda, alsc by igniting zirconia with an
alkaline hydroxide. ‘‘Zirconate of potassium thus ob-
tained, dissolves completely in water.’’ His first mode
of preparing the zirconates is very questionable; the last
statement is not true. He then goes on and describes
zirconates of sodium, calcium and magnesium, as describ-
ed by Hiortdahl. The details of Hiortdahl’s analyses,

1 Ann. Chem. Pharm., 137, 34, 236.
’ 2Compt. Rend., 112, 144-46, and 113, 1021-22.

2 JOUUNAL OF THE

etc., will show on what an imperfect basis the knowl-
edge of the constitution of these bodies rests. Hiortdahl
states that he secured direct union only by ignition with
alkaline carbonates. His attempts with the volatile chlor-
ides failed. On heating zirconia with sodium carbonate
one equivalent of carbon dioxide was driven out, and it is
on the loss of carbon dioxide upon ignition that his figures
for the composition of the resulting products are largely
based. On heating equivalent amounts of zirconia and
sodium carbonate a crystalline mass was obtained, which
slowly absorbed moisture from the air. On treating this
with water no decomposition was noted at first, but
soon the water became alkaline and zirconia separated.
This was taken as proof that the zirconia was decompos-
ed by the water. In the experiment 0.3910 gram zirconia
heated with 0.3130 eram sodium carbonate to a dark red-
ness for nine hours lost 0.1310 gram carbon dioxide, and
on treatment with water 0.3871 gram ‘‘zirconia,’’ or 99.03
per cent. was left. If an excess of sodium carbonate is
used can one drive out two equivalents of carbon dioxide.
A little further down he notes that the ‘‘Gewichtsverlust
zugleich von der Temperatur und der Dauer des Gliihens
abhanet.’’ These are the determinations from which
formulas for the zirconates are worked out.

It is scarcely necessary to say that for purposes of cal-
culation these figures are entirely worthless. The loss
of carbon dioxide is due to a partial formation of hydrox-
ide as well as to a combination with zirconia. ‘The fused
mass of sodium carbonate, hydroxide, zirconate and un-
changed zirconia will of course prove hygroscopic, and
water will wash away all except the last two mentioned.
We have failed to get any positive evidence that a zircon-
ate formed by fusion was decomposed by water or was
appreciably soluble in it. °

In his second paper, Hiortdahl treats the fused mass of
zirconia and sodium carbonate with water acidified with
hydrochloric acid and analyzes the residue, finding in it:

i.
=

ELISHA MITCHELL SCIENTIFIC SOCIETY. 3

ZrO,, 78.54 per cent.; Na,O, 5.40 per cent.; and H,O,
16.89 per cent., corresponding to Na,O.8ZrO,. He gets
zirconate of magnesium and calcium by fusing zirconia

and silica with magnesium chloride and calcium chloride

respectively.

Ouvrard obtained his zirconates by fusions with the
chlorides, also using those of lithium, calcium, strontium
and barium. In some cases, instead of using zirconia, he
took powdered zircons, obtaining silico-zirconates.

In our own experiments the following methods of form-
ing the zirconates were tried:

J. Fusing in boron trioxide the zirconia and the basic
oxide (Kbelmen). ;

Il, Fusing zirconia with alkaline carbonates, (Hiort-
dahl).

Ill. Fusing zirconia with alkaline hydroxides.

IV. Fusing zirconia with alkaline or earthy chlorides
(Hiortdahl).

V. Precipitation of solutions of zirconium salts with
alkaline hydroxides (Watts).

VI. Dissolving zirconium hydrroxide in strong solu-
tions of sodium or potassium hydroxide and precipitation
by'dilution or by neutralization with an acid.

I. FUSION WITH BORON TRIOXIDE.

This method, made use of by Ebelmen in the case of
other oxides, is useless in the case of zirconia, because
this oxide is not taken up by the boron trioxide, and so
does not come in contact with the other oxide. The melt
of boron trioxide was kept at a high temperature fora
number of hours without any appreciable solvent action
upon the zirconia, added in small portions.

II. FUSION OF ZIRCONIA WITH ALKALINE CARBONATES.

The purified zirconia used had been dried at the tem-
perature of the steam bath and therefore was not in the

inactive condition brought about DY eRe a Sara

4 JOURNAL OF THE

high temperature. This was the case in the subsequent _

experiments also.

It is by fusion with sodium carbonate that Hiortdahl
claimed to have prepared his zirconates. Ouvrard seems
to have gotten little besides crystals of zirconia. Very
little action could be seen in the experiments described
below. ‘The zirconia sank to the bottom of the fused
mass and remained without apparent change for hours.
Varying the time of heating did not seem to have much
effect upon the results. )

After the fused mass had cooled it was leached with
successive portions of water until no alkali could be de-
tected. ‘The wash water contained no zirconium. As
the mass left will absorb carbon dioxide, it was dried as
rapidly as possible at about 150° to constant weight. Di-
lute hydrochloric acid was used to separate the zirconate
formed from the unchanged zirconia. As this zirconia
was now in the ignited and even crystalline form, it was
concluded that it vas insoluble in the dilute acid. The
zirconia in the solution was precipitated as hydroxide and
determined as oxide, and the alkali determined in the fil-
trate. Two grams of zirconia were used in each case
‘and a large excess of the carbonate. The amount of
unattacked zirconia ranged from ninety-three to ninety-
nine per cent., showing thus very little action after many
hours of fusion. In some cases, therefore, the amount of
supposed zirconate obtained was too small for reliable
analysis.

I WITH SODIUM CARBONATE.

Three experiments with sodium carbonate were carried
to completion.

1. Two grams zirconia and eight grams sodium car-
bonate were fused three hours. Amount of residue after
leaching, soluble in dilute hydrochloric acid, 0.1588 gram,
or eight per cent. In this ZrO,=75.70 per cent.; Na,O
= 24.30,

ELISHA MITCHELL SCIENTIFIC SOCIETY. 5

2. Two grams zirconia fused with sixteen grams

‘sodium carbonate for four hours. Amount of residue

soluble in hydrochlroic acid, 0.3042 grams. Percentages:
ZrO,, 74.18; Na,O, 25.81. These correspond fairly with
(ZrO,);(Na,O)),.

3. Two grams zirconia fused with sixteen grams so-
dium carbonate for eight hours. Amount soluble in di-
Inte hydrochloric acid 0.1220 gram, or six per cent.
Percentages: ZrO,, 58.16; Na,O, 41.84.

II WITH POTASSIUM CARBONATE.

When potassium carbonate was used the action was so
shght that it was not possible to get enough for analysis.
In one case, after heating for ten hours, the amount solu-
ble was just one-half per cent. This accords with the
observation of Ouvrard.

Of course it is possible that the leaching with water
had a partially decomposing effect upon the zirconates.
Very little could be justly concluded, however, from ex- |
periments in which there was so little action, therefore
the effort at forming the zirconates by fusion with the
carbonates was abandoned.

Ill. FUSION OF ZIRCONIA WITH TlYDROXIDES.

1. Fusion with sodium hydroxide.

Here considerable action was noticed. The fusions
were made inasilver dish. The heating was kept up un-
til the mass became semi-solid. The treatment of the
fused mass and the analysis were carried out as before.
No zirconium was detected in the wash water.

1. Two grams zirconia fused with eight grams sodium
hydroxide. Total amount dissolved, 1.1855 grams. An
analysis, reduced to dry basis, gave ZrO,, 92.29, and Na,O,
7.05.

2. Same amount taken as in experiment 1. Total
amount dissolved 0.7655 gram, containing ZrO,, 93.19,

and Na,O, 6.22.

Ma JOURNAL OF THE

3. Two grams zirconia and sixteen grams sodium hy-
droxide. Amount dissolved 0.8004 gram, containing ZrO,,
257 anda, 38:

4. Two grams zirconia were fused with eight grams
of sodium dioxide, instead of the hydroxide. Amount dis-
solved 0.7074 gram, and this contained 91.21 per cent.
ZrO,.

Na,O.(ZrO,), contains ZrO,, 29.30; ans NaF,, 7.80.

Na,O.(ZrO,), contains ZrO,’ 93.29; and Na,O, 6.79.

2. Fusion with potassium hydroxide.

These were carried out in a manner similar to those
with sodium hydroxide and the action seemed to be about
the same. In each experiment two grams of zirconia were
taken and fused with sixteen grams of potassium hydrox-
ide.

1. Dissolved by hydrochloric acid 0.8850 gram which
contained 79.63 per cent. ZrO,,

2, Dissolved 1.5241 grams which contained ZrO,, 82.98;
17-00.

3. Dissolved 1.2078 grams which contained ZrO,, 78.59;
K,O, 21.40.

4. Dissolved 0.9297 gram which contained ZrO,, 85.51;
K,O, 14.49.

In analyzing these alkaline zirconates the water pres-
ent was not determined. The moist powder was treated
with hydrochloric acid, the insoluble portion caught upon
a filter, and the zirconia and alkali determined in the fil-
trate and the results calculated upon a dry basis. If the
analysis given by Hiortdahl is calculated upon a dry basis,
it gives for ZrO, 93.51,and Na,O, 6.49, or very nearly the
the numbers gotten in experiment 2 in the fusions with
sodium hydroxide.

It is difficult to interpret the results of these fusions

with the alkaline carbonates and hydroxides. ‘The fusions -

do not yield the same definite results each time, and in-
deed it cannot be claimed from the analyses that definite
zirconates have been prepared. Some allowance must be

s +
af
Sv ;

~~

‘®

ELISHA MITCHELL SCIENTIFIC SOCIETY. 7

-

made for the imperfect method of separation of the zir-
_ conate from the unchanged zirconia, some of the former

being taken up by prolonged digestion with hydrochloric

acid. ‘There isa marked tendency, however, toward the
formation of certain zirconates under approximately the
same conditions. ‘Two of the experiments with sodium

carbonate give results fairly in accordance with the for-
cela (Na,O),(ZrO,),. In the fusion with sodium hydroxide
‘the results range from (Na,O) (ZrO), [GrO,=90.76: Na,O
=9.24], to (Na,O) (ZrO), [ZrO,=—94.08; Na,O—5.92], and
it is with these that the analysis of Hiortdahl agrees,
though his was a fusion with sodium carbonate. Why
there should be this difference is not clear. ‘The tenden-
cy is manifestly toward the formation of what may be
called the polyzirconates, having a considerable excess of
zirconic acid. In the case of potassium the carbonate
failed to givea compound. ‘The hydroxide gives results
ranging from

0 7)(Z4r0,),[4rO,—79.57; K,O—20.43], to (ZrO,),CK,O),

[ZrO,=86.74; K,O=13.26]; again polyzirconates with ex-
cess of Zirconia.

Other-fusions were carried out with sodium and potas-
sium hydroxides, and the resulting masses were leached
with dilute acetic acid, a solvent which had to be used in
- leaching away the alkaline earths in the subsequent ex-
periments. In the case of sodium the leaching removed
practically all of the alkali. Inthe case of potassium a
_ substance containing ZrO,, 78.59 per cent., and K,O, 21.41
per cent. was left. This nearly corresponds to the form-

ula K,O.(ZrO,),. It is almost exactly the result gotten
in one of the previous experiments.

3. Lithium gave no zirconate when the carbonate was
used for the fusion. With the hydroxide it gave the fol-
lowing results: .

Two grams ZrO, were fused with excess of lithium hy-
droxide, leached with dilute acetic acid and with water.
‘This gave on analysis ZrO,, 89.11 per cent.; Li,O, 10.99

ee. Se ee

= —

8. JOURNAL OF THE

percent. Percentage of ZrO, calculated for Li,O.2ZrO,
is 89.13;

4A. Calcium oxide was also heated for a number of hours
with zirconia and gave the followiug results: ©

Caleulated for

if ki CaO.ZrO¢.
TOUR or i aibrctsi ei cuee atact 70.11 70.83 68.54
CT 86 AS eee tee 29.88 29.14 31.16

These residues, after treatment with dilute acetic acid
and water, were crystalline.

5. Barium hydroxide differs from that of calcium in
that it fuses readily and thus affords much better oppor-
tunity for reaction. The fusion gave abundant evidence
of action. The excess of hydroxide was washed out with
water. ‘The carbonate present was dissolved away with
dilute acetic acid until there was no more barium in the
wash water. No zirconia was found in any of these wash-
ings. ‘Towards the latter part of the washing the solid
particles settled out with great difficulty. The residue
was analyzed with the following result:

Calculated for

Found. BaO.ZrO 9
PDE ey Sb kG sade kicay 66,5058 eee 55.95
Pes Sant sain {vee eee 44.49 44.05

This is a grayish white powder, very fine and easily
soluble in hydrochloric acid. Practically all of the zir-
conia was taken up, leaving little undissolved by the hy-
drochloric acid.

6. Strontium oxide was prepared by ignition of the
nitrate and heated in the same way as the calcium oxide.
This mass was pinkish white, probably from slight im-
purities, and was completely soluble in dilute hydrochlor-
ic acid. On analysis the following results were obtained:

Calculated for

Found. SrO ZrOe
‘cy O FN y es Womenre dion” eaaenoel Se LU Mn 3 ite.) 54.55
aR os ee uk Late ie gt an es 45.77 45.45

ss Mis |
/. The magnesia(eight grams)and zirconia(two grams)

;
*
J
.

*, SS
. ~
7

ae

ELISHA MITCHELL SCIENTIFIC SOCIETY. 9

was heated together for about four hours and then treat-
ed in the same manner as the calcium fusion, z.e., first
leached with dilute acetic acid and then washed with
water until free from magnesia. The residue gave evi-
dence of being crystalline.

Calculated for

Found MgO.ZrOe
SSO pag ae Ea a 76.28 75.30
1 Se NE Ue ee REE a ge 23.70 24.70

Iv. FUSION OF ZIRCONIA WITH CHLORIDES.

This method was used by Hiortdahl in preparing the
zirconates of magnesium and calcium, and by Ouvrard for
the same, and also for strontium, barium and lithium.
According to the latter they all gave zirconates of the
form M,ZrO,.

I. Fusion with sodium chloride.

There appeared to be very little action. The fusion
was washed with water until free from chlorine. It was
then treated as in the case of the carbonates. When two
erams of zirconia were fused with sixteen grams of sodium
chloride, it was found that less than two per cent. had
been dissolved. In a second experiment, after heating
six hours, the amount dissolved was less than two-tenths
of a per cent.

2. Fusion with potassium chloride.

No action was observable. When two grams of zir-
conia were heated a number of hours with an excess of
potassium chloride and the mass then treated as above,
only three-tenths of a gram had beenacted upon. There
seemed to be even less action in the case of lithium chlor-
ide at the temperature attainable by means of an ordinary
water-blast lamp.

3. Fusion with alkaline earths.

Two attempts were made to prepare magnesium ir-
conate by fusing zirconia with magnesium chloride
and ammonium chloride. It was not possible to prevent

10 JOURNAL OF THE

decomposition of the magnesium chloride. There seemed
to be some action, but much difficulty was experienced in
separating the products. The method described by Ouve -
rard gave evidences of zirconium in the washings.

In the case of fusions with calcium chloride no action
could be observed. ‘Two experiments were made, follow-
ing closely the directions of Ouvrard, except as to tem-
perature possibly, as to which no exact directions were
given. A water-blast lamp was used tor several hours.
After leaching and washing, the mass left behind gave
no zirconium to hydrochloric acid.

Our experiments with the chlorides have led us to be-
lieve that there is little or no action between zirconia and
the chlorides of the alkalies or alkaline earths except
where these chlorides are decomposed by the heat and
oxides formed. Any action noticed is to be attributed to
the oxides.

V. PRECIPITATION FROM THE SOLUTION OF A ZIRCON-
IUM SALT BY MEANS OF AN ALKALINE HYDROXIDE.

Watts speaks of this method but no experiments are
recorded. It seemed to us upon examination of the ques-
tion that very little evidence as to the existence of the
zirconates or their properties could be drawn from such
a method of preparation as this. It has been repeatedly
observed that the precipitate formed by means ot am-
monium hydroxide is extremely hard to wash free from
ammonia. After a very large number of washings, how-
ever, itis practically free from ammonia. The same is true
of sodium and potassium hydroxides. Isit to be inferred
that a definite zirconate is precipitated? At what point
shall the washing be stopped, for manifestly some wash-
ing 1s necessary? Equally, it cannot be decided because
of this loss of alkali by prolonged washing, that we have
a decomposition of the zirconate caused by the action of
the water. It, therefore, seems to be quite useless to make
analyses of the precipitates gotten with different degrees

» © ie

ELISHA MITCHELL SCIENTIFIC SOCIETY. 11

of washing; especially as somewhat similar experiments
were carried out under the next heading.

VI. THE SOLUTION OF ZIRCONIUM HYDDOXIDE IN CAUS-

TIC ALKALI.

It was found that zirconium hydroxide was percepti-
bly soluble in solutions of potassium and sodium hydrox-
ide. Experiments were first made with a view of deter-
mining the extent of this solubility. Solutions of the two
alkalies were made up of different strengths, an excess
of zirconium hydroxide added, and the solution ‘then boil-
ed. After cooling, a measured quantity of the solution
was drawn off and the amount of zirconia present deter-
mined.

A 50 per cent solution potassium hydroxide dissolved per ce 0.00233 gm.

33 sé te ee se vs ‘eé ee ve 0.00097 ee
25 66 be 6s 66 F ‘. a a te 0.00075 tc
12 oe be ay te 6s eb es a 0.00009 ce

In the case of sodium hydroxide there seemed to bea
stronger solvent action.
A 33 per cent solution dissolves per cc. 0.00245 gram.
“Se aa ‘s FSR BOLD: is 1
Meas veal ee Mile aR ERE Ie ODOR ids
If a concentrated solution of alkali, saturated with zir-
conium hydroxide, is diluted, a portion of the zirconium
will be precipitated. Neutralization with acid will also
cause a precipitation of the zirconium. In both cases
alkali is retained by the precipitate in spite of washing.
Analyses were made of some of these precipitates after
very thorough washing (in no case was less than a liter
of water used.) ‘The results in four experiments were
sufficient to show that these precipitates were practically
zirconium hydroxides with a varying percentage of alka-
li, this percentage ranging from 1.15 to 3.94. It is pos-
sible to assume that zirconates were formed and then de-
composed by the action of water during the washing,
but it seems more probable that this is, as is true in the

12 JOURNAL OF THE

case of so many hydroxides precipitated by alkaline hy-
droxides, merely a stubborn retention of alkali. Assum-
ing that the strong alkaline solutions held zirconates in
solution, attempts were next made to prepare other zir-
conates by precipitation from them.

The addition of solutions of various salts gave small
precipitates which seemed to be formed mainly because
of the dilution of the alkaline hydroxide and to consist
almost entirely of zirconium hydroxide. It was neces-
sary, therefore, to use strongly alkaline solutions of the
compounds of the elements to be experimented with.
This greatly diminished the choice of compounds. Con-
centrated solutions of aluminum and zinc hydroxides in
potassium hydroxide gave precipitates but they were in
too small amounts for reliable analyses to be made.

Summing up the results of the experiments performed,
it is clear that the method yielding the best results for
the preparation of the zirconates is fusion of gently dried
zirconia with hydroxides or prolonged heating with the
oxides. In the case of the alkaline earths this yields zir-
conates containing one equivalent of each oxide,CaO.ZrO,,
etc. The same is true of the magnesium compound.
For lithium the compound obtained was LiOZrO,. For
the alkalies it seemed to be possible to obtain only zircon-
ates having a largely preponderating proportion of zir-
conia. ‘There seems to be a tendency toward the forma-
tion of distinct compounds under certain conditions.
These polyzirconates, and the lithium compound also,
may be decomposition products due to the action of the
water used in leaching. No other mode of separation
from the products of the fusion could be devised by us,
however, If they are produced by the decomposing and
solvent action of water, it isa little strange that a point
should be reached beyond which the leaching extracted
no more alkali, and that this point varied with changed
conditions. ‘This is not the case where zirconium hy-
droxide has been precipitated by an alkali.

ELISHA MITCHELL SCIENTIFIC SOCIETY. 13

DOUBLE ZIRCONATES.

Two attempts at the formation of double zirconates
were made.

I. Potassium calctum zirconate.

About two grams each of zirconia, potassium hydrox-
ide and lime were heated together for about four hours.
There was evidence of considerable action. The mass
was treated with dilute acetic acid and thoroughly wash-
ed. Then on treatment with dilute hydrochloric acid
nearly the whole residue went into solution. ‘The analy-
mepeawe Ar), 67.21. per cent.; CaO, 31.06; K.OLRTE
This is a calcium zirconate, (CaO.ZrO,), with a small
part of the CaO substituted by K,O.

2. Potassium aluminum zirconate.

Two grams of zirconia were fused for eight hours
with two grams potassium hydroxide and three grams of

- alumina. /’Che mass was washed with dilute acetic acid

until no more alumina was dissolved. The residue was
treated with dilute hydrochloric acid and the insoluble
portion removed by filtration. The analysis gave ZrO,
72.38 per cent; Al,O,, 7.66; K,O, 20.00. These experi-
ments indicate the possible existence of double zirconates,
and when time permits this point will be further examin-

ed.

RIVER ADJUSTMENTS IN NORTH CAROLINA.

W. J. WEAVER.

Nore.—In presenting this paper I beg to acknowledge my
indebtedness to the lectures of Prof, Collier Cobb, and to his
work and that of Messrs. Chas. Baskerville, R. H. Mitchell
and other members of the class engaged in advanced work in
Physical geography; but the mode of presentation is my own
and I alone am responsible for any short-comings it may have.
As my paper was presented for the Kerr Prize in Geol-

/

14 : JOURNAL OF THE

ogy it has not even had the critical reading of the head of the
department, and lack of funds prevents my presenting as
many maps as were contained in the paper,

North Carolina is natually divided in three sections:
(1)The Eastern or Costal plain; (2) The Piedmont Sec-
tion, and, (3)The Western or Mountain District.

The costal plain runs inland abo: 100 or 125 miles.
‘Its western boundry line runs from the western part of
Warren through Franklin, Wake, Cumberland, Chat-
ham, Moore, Montgomery, and Anson counties.’’ The
whole coastal plain belongs to the Quarternary system,
with frequent expanse of the Kocene and Miocene of the
Tertiary along the rivers and ravines. As we go inland
the country rises about one foot per mile, but from North
to South is almost level. Over the whole section the
primitive rocks are covered with a deep stratum of earth,
principally sand. Along the western border and river
courses we find granite, slate, and other rocks sparingly
distributed, but no rocks of any kind can be tound any
where else in the region. The section is made up of beds
of clay and sand with vast quantities of shell imbeded in
them. ‘The upland soil is mostly sandy loam which yields
very good crops. ‘There are vast areas of sand that will
not yield anything but pines. In fact we know that this
whole region has in recent geological time been raised
above the sea level. *

The Piedmont Section begins on the western edge of
the coastal plain and runs west to the borders of the
Blue Ridge. It is a rolling prairie in the east and gets
rougher towards the west, including some small mountain
ranges, the Brushy, Pilot, and King’s Mountain. The
mountain chains of the western part of the Piedmont belt
run northeast and southwest; and as the rivers pass them

they form rapids and falls that give excellent opportunity -

for manufacturers.

1. Handbook of North Carolina, 1885, published by Board of Agri-
culture.

ie =

t

4

ELISHA MITCHELL SCIENTIFIC SOCIETY. 15

Though you would expect a very rough hilly country
on the West you do not findit so. The slope on the east-
ern side of the Blue Ridge is much steeper than that of
the West. West of the Blue Ridge we havea very large
valley bounded on the East by the Blue Ridge and on the
West by the Great Smoky Mountains. This valley runs
northeasi and southwest between the two mountain chains
and composes the mountainous districts of North Caro-
lina.

This area has principally crystalline schists and gneisses
with patches of conglomerates, sandstones, and shales and
limestone. Both the Smokies on the West and the Blue
Ridge on the East presents an anticlinal structure; the
latter often having its monoclinal member absent. ‘The
area was in all probability once covered by an eastern ex-
tension of the Paleozoic rocks of East ‘Tennessee, the
sandstones of the western district being probably Cam-
brian (Chilhowee or Potsdam), the patches of limestone
probably Silurian, and the grits and shales farther
Kast possibly Carboniferous.' I assume that the fold-
ing that produced the Appalachian System was, as
in Pennsylvania, rapid enough to deform the river systems.
It gave rise to four great systems in North Carolina.
The first we may call the Deep River syncline. It had
its head in Chesterfield County, South Carolina, on the
North Carolina line and ran northeast into Virginia. The
second had its head in Caldwell County, North Carolina
ran east of northest and joined the first in Virginia.
This one may be called the Dan River syncline. The
third had its head in Catawba County, North Carolina,
and ran south into South Carolina. This may be called
the King’s Mountain syncline. The fourth, which we
may call the Ashev !'esyncline was rather a canoe-shaped
basin with a length of about 150 miles and a width of 20

1. Professor Collier Cobb’s Lectures on General Critical Geology,
1893-94; see also Cobb’s Map of North Carolina, 1887,

16 JOURNAL OF ‘THE

miles in Watauga county and 50 miles in Henderson. Its
ends are in Virginia and Georgia, and it took a Northeast »
and Southwest course. It was probably a lake for along
time until it flowed over, most probably in Henderson
county. We find evidences of shores in Transylvania
county that were evidently made by alake. These syclines
and the rivers that occupied them may be seen on map (1)
It can be seen from the map that the original drainage of
western North Carolina was not asit nowis. Yet the
present rivers are in many cases in the original river beds.
The original river of the Asheville syneline headed in the
northwest with what is now New river, ran southwest
and crossed near Boone into the head waters of Watauga
river, ran along the head waters of Watauga, but in the
opposite direction taken by the Wautaga now, for a few
miles aud crossed into the head of what is now Linville
river, ran down the stream for about 20 miles and crossed
into Brush creek and then into Toe river. At this
point Linville river now enters what is known as the
gorge. 'Thisisa very deep valley that has been cut
since the original drainage we are describing. The river
that cut through this great plateau has captured the
Linville river and led it through, but at the time we are
describing this gorge did not exist and the natural
outlet was through Brush creek as stated. The river
continued down Toe river as far as the fork known as
South Toe, and there it crossed the present gap known
as the Toe river gap. DownSwannanoa to French Broad
and up French Broad and out through Mud creek into
South Carolina, thence to sea. The drainage on the
southwest began with the Hiwassee river which has since
been captured and inverted, and ran east or a little south
of east to Valley river, up Valley river, across Red Mar-
ble Gap and into Nantehala river, down this to its junc-
tion with Tuckaseege river, thence up Tuckaseege and
across what is now known as Road Gap, down Richland
creek to Pigeon river, up Pigeon to the great bend and

*LISHA MITCHELL SCIENTIFIC SOCIETY. 17

thence across Hominy Gap and down Hominy into the
French Broad, up French Broad and out through Mud
creek into South Carolina. We have many of our rivers
in the original river beds. The Hiwassee has been cap-
tured and inverted but it still occupies the old bed. The
Nantehala and Tuckaseege still occupy their old beds
though there has been considerable change, a part of the
latter having been inverted.

We would expect to find in these inverted rivers evi-
dence of it in their sluggish movement but we must re-
metmber that most of them have since their inversion been
so much lowered that they are the roughest to be found.
The Little Tennessee River has cut a gorge through the
Great Smoky Mountains over four thousand feet deep and
we could hardly expect a river to be slow and sluggish
whose lower waters had been lowered so much. Like-
wise the French Broad from above Hot Springs is very
tough owing to the same fact. On the northwest the
New river was made by cutting into the syncline and

leading a part of the original river out. In map (I) wesee
that it is about to cut into the syncline and capture a
part of the original river. Its headwaters push forward
into the syncline until it has captured the headwaters of
the original river and inverted a small part of it. This
inverted part having a greater fall will move the divide
southwest by degrees; and this continues until it reaches
the mountain ranges near Boone which on account of its
structure marks its final divide. The next stream that
cut into our original river was the Watauga. It cut
through the Smokies from Tennessee and led off a por-
_ tion, but did its best work in determining the divide for
_ the other rivers. The strata not all being of the same
hardness we can see why these captures went as far as
_ they did and no farther. When New River was inverted
i it probably would have led out much more of the streams
_ of the northern and middle portions of the basin but for
_ the fact that there was a ledge of rock that outcropped

2s

_

-.
a
ae |

Ce

18 JOURNAL OF THE

about the central part of Watauga county and ran en-
tirely across the basin at that point. These rocks had no
influence upon the streams until the streams had levelled»
‘the country down to them. ‘Then they formed a natural
divide and fixed definitely the headwaters of New River.
The Watauga was probably captured by a westward flow-
ing stream on the southwest of these and therefore could
not capture any of the Néw River’s headwaters. Fur-
ther on :the south of the Watauga and running parallel
to it there is another outcrop of rocks which run across
the basin and join the Blue Ridge at Grandfather’s Moun-
tain, thus fixing definitely the divide between Linville
and Watauga rivers. From this divide the river which
goes south is Linville, which runs in the channel occupied
formerly by the original river. This channel has the
highlands of the Blue Ridge on the south and east; and
on the west there is a range of mountains which separate
Linville and Toe River. Linville River now runs down
this valley about twenty miles and then enters what is
known as the gorge. The original river formerly passed
over and went down Brush Creek, Linville gorge not
having been cut at that time, to Toe and down Toe as far
as where South Toe enters. The Linville gradually
onawed its way back through a vast plateau and tapped ©
the original river, thus leading off a few miles of it. We ~
will also note that Linville is the only river that captured —
a stream from this basin and led it out to the east, all ~
the rest have been captured and led off tothe west through ~
the Great Smokies.

The next capture was that of the headwaters of the
Toe by the Nolichucky. ‘This led all the North Fork of
the original river out except the Swannanoa which still re- _
tains its old position. As the Nolichucky cuts through
the Smo'xy Mountains it gradually lowers its channel and
lowers tle whole of the river. As the Nolickucky cuts
its way back it furnishes a shorter route to the lowlands
ani being’ shorter it hasa more rapid current which cuts

ges

ELISHA MITCHELL, SCIENTIFIC SOCIETY. 19

its channel faster and the divide migrates eastward un-
til it is finally permanently located at Toe River gap, all
the waters of the northwest having been captured by
westward flowing streams. The next capture I shall
take up belongs to the southwest tributary of the original
river. ‘The Hiwassee originally formed the headwaters
of the river that drained the southern end of the Ashe-
ville syncline and led its waters up to the French Broad
and thence out by that river. It is almost if not quite im-
possible to determine which of these captures took place
first and in what order the others followed, but Iam in-
clined to think that the rivers of the northeast were cap-
tured pretty much in the order that I have treated them,
1. e., the headwaters (New River) were captured first,
then a new stream cut in and took another deal off the
head ‘and so on do wn; in the southwest it is most probable
that they did take this order. Considering the amount
of erosion that the Little Tennessee has done I think that
that stream was the first one to cut through and make a
capture, thus draining all the basin west of the Balsam
Mountains. Later the Hiwassee was captured and in-
verted and now runs out the southwest end of the baisin.
We can see by comparing the sketch of the original
drainage with the map of to-day that the capture would
turn a large volume of water through the Little Tennes-
see’s gorge and thus help to sink it very rapidly. This is

-most probably what happened. As evidence of capture

and inversion in the Little Tennessee River we have sev-
eral rivers coming into it like the barbs on an arrow; 1. e.
they show their former tendency to run the other way.
The Hiwassce also has several branches coming in in that
manner, as the Nattely River and Shoal Creek. In map
(I) we can see the river system of the Asheville syncline as
it originally was. We see the little Tennessee and the
river that captures the Hiwassee just cutting through
the Great Smoky Mountains and looking in upon their

prey. They are moving their respective divides to the

20 JOURNAL OF THE

east and this continues until the divides have moved to
their present position, and by this time the Little Ten-
nessee has captured and inverted all the waters west of
the Balsam Mountains and the divide has moved to Road
Gap where it stops on account of the rocks that outcrop
here. ‘The Hiwassee is gradually overcome and captured
in asimilar manner. ‘This only leaves Pigeon in its orig-
inal position and running over what we now call Hominy
Gap to the French Broad, and on the west we see the riv-
er that is to capture it cutting through the Smokies and
gradually capturing its headwaters until they are finally
all captured and led out through the Smokies. The New
Found Mountains form a barrier between this river and
Hominy Gap—the bed of the original stream is still the
lowest gap in these Mountains.

The creek that flowed from the gap to French Broad is
Hominy Creek and since the days of the readjustment it
has recaptured two of its old tributaries; 1. e. the two
small branches that once ran to Pigeon River, now run
into Hominy Creek and thence to French Broad*. All these
waters that originally found their way to the sea through
the upper French Broad valley would have made a large
valley and such we find to-day. This stream has been cut
into and captured by astream from the west thus invert-
ing the French Broad from its original course. ‘The
French Broad from the mouth of Swannanoa to Brevard, a
distance of about forty miles, is a very smooth, sluggish
river, so slow in its movements that one can but notice it
and compare it to other mountain streams that usually go
so rapidly. This is evidence of an inversion which has
evidently taken place. From Asheville west, the French
Broad is noted for its beauty, which consists in its rough,
rugged course over rocks and through gorges, winding its
way through the Great Smokies into the Appalachian.
River. ‘There is very little fall in the French Broad be-
tween Brevard and Asheville while between Asheville

* National Geographic Magazine, vol, I, no. 4. By Bailey Willis,

ELISHA MITCHELL SCIENTIFIC SOCIETY. 21

and Paint Rock there is a great fall. At Asheville the
altitude of the river is about 2100 feet while at Paint
Rock it is 1264, thus giving a fall of 181 feet to the mile.
The town of Brevard is lower than Asheville but both
towns. are above the river. However I believe that there
~would not be a difference of many feet in the altitude of
the stream at the two places. Wecan see from map of
the original drainage the French Broad as it ran south-
east, with the river that is about to capture it cutting
through the Smokies and having their divide just east of
the Tennessee line. As in the other cases the divide has
migrated east and the western river has captured and in-
verted the French Broad and led it out to the west. This
finishes up the Asheville basin or syncline. Now let us
look at the others. The next one I will take up is the
old Dan River syncline which I have described above.
It has had two changes. First it has been cut into by
the Yadkin which has led about 50 miles of the Dan River
headwaters to the sea through its channels and secondly
it has had numerous readjustments through its headwa-
ters and those of John’s River, a tributary of the Ca-
tawba. In the drawing of the original drainage, map (I,)
we can see the position of this syncline which originally
extended into Virginia and met the Deep River syncline.
In the drawing we see that the Yadkin is about to cut
into the Dan and as soon as it cuts through it will take
the waters to the sea because having a shorter distance.
to go it must have a greater fall and will hence take the
Dan in preference to being captured. The Dan was thus
turned from its course and led to the sea by the Yadkin.
The present Dan River has a branch, Town Fork, that
still follows the old bed. The headwaters of the Yadkin
have extended themselves still further north and are now
known as the Ararat River. We will now turn our at-
tention to the captures made in the headwaters of the
syncline; and this brings me to mention a fifth syncline in
North Carolina which I had not noticed until after 1 had

22 JOURNAL OF THE

begun my work on this paper. This syncline we may
call the Round Knob syncline since Round Knob is in the
syncline and near its head. It began in the west of Mc-
Dowell and ran a little north of east through Burke and
Iredell counties, and’ it is probable that it continued
through Davidson, Randolph and Chatham and joined
the Deep River syncline in the latter county although
we have no definite evidence that it did. In Map (I) we
can see the drainage of this syncline as well as the cap-
tures which its waters made on those of the Dan River
Syncline. I was at first disposed to think that John’s
River had captured the branch of Yadkin called Yadkin
and that later it had been retaken by the Yadkin, but
upon examination I find that those branches near the head
of the Yadkin come down from a high plateau and enter
the Yadkin at right angles and 1am convinced that the
branch called Yadkin is merely conforming to the family
trait and has never been captured by John’s River. If
we look at the branches now called John’s River and Buf-
falo Creek we find they have the Yadkin family traits
and, they show they have been captured by John’s River.
As the Yadkin cut into and captured the Dan so the
Round Knob Syncline has been cut into by the Yadkin and
probably by the Catawba and its waters have not gone
through the Deep River as they probably did at first.
Third Creek is probably nearest the old channel that
traversed Round Knob Syncline. The Catawba that cut
into the Round Knob Syncline ran a little east of the
King’s Mountain Syncline originally and it was its trib-
utaries that cut through the eastern side of this syncline
and led its waters out. The River that originally occu-
pied the syncline was most probably what we call West
Fork of Catawba River. This joined the Catawba where
it passes to South Carolina. We see from the original
diagram that the tributaries of the Catawba are about to
cut through the eastern border of the King’s Mountain
syncline and lead its waters to the Catawba, and as time

4
4
7
;

ELISHA MITCHELL SCIENTIFIC SOCIBTY. 23

passed we see they kept pushing to the west until they
have obtained the position they now occupy. Dutchman’s
Creek has cut through and branched in the syncline and
now drains the whole of it. West Fork of the Catawba
which was originally in the syncline has cut through the
western border and now drains a large area northwest
of the syncline; thus in time the rivers have changed
their positions and have so greatly eroded the syncline
that we only find traces of it left, Such as Anderson and
King’s Mountain on the west, and on the east not even
so much, however we can trace its borders between Dutch-
man’s Creek and Catawba.

The Deep River syncline headed in Chesterfield county
South Carolina, and ran northeast to Virginia where it
joined the Dan River syncline. We can see its position
by turning to the general drainage Map of North Caro-
lina after the Permian uplift, (Map I). Its eastern bor-
der still makes the fall line in our rivers, but its western
borders were not so well marked, and did not have so
definite a boundary. Infact the eastern border was a
wide spread of country gradually sloping into it. ‘The
eastern border may be seen by drawing a line from
Cheraw, South Carolina, northeast passing about ten
miles east of Raleigh and striking the Virginia line where
Dan river enters North Carolina. Along this line is
an outcrop of a number of the older rocks, principally
granite. (Hand Book of-North Carolina, 1886.) Anda
little west of this is the old Deep River bed. ‘The river
headed in South Carolina with Brown’s Creek and ran
northeast to the Pee Dee River which formed a part of
its bed, up whatis now Little river, across to Wolf’s
Creek, down this to Deep river and down Deep river to
Haw river where it turned up what now is New Hope
river and across to Stone Creek, down this and up Knopf
of Reed’s Creek across to Tar river, up this, and to Fox
Creek, over to Grassy Creek and down to the Dan river.
At this time the coast line was only a few miles east of

24 JOURNAL OF THE

this and the rivers such as Roanoke, Tar, Neuse, Cape
Fear and others had not cut back to the syncline, however
the distance to the sea was smalland the fall was com-
paratively great and they were gradually cutting away.
In drawing (Map 1) we can see how they cut this original
deep river up and send their streams on westward for other
adventures. The Great Pee Dee cut into the syncline near
its head and led off Brown’s Creek and inverted and led
off Little river, then sent one of its streams on northwest
and at last under the name of the Yadkin it cuts into the
Dan River Syncline and captures a large part of its head-
waters as we have described above. Cape Fear cuts into
the syncline and leads off the part we now call New Hope
and sends its branches on to help drain the territory
northwest of thesyncline (note the slowness of New Hope
River). The Neuse cuts in and leads off a small portion
as does the Roanoke, and thus helps the waters to finda
shorter route to sea. At last this syncline leaves us this
remnant of its former self as evidence of what it has been
The inverted creeks and rivers are yet at a loss to know
what to do and so move along slowly, but by and by
when they get accustomed to their new environment they
will pick up their spirits and move along joyously as they
did of old, and later generations will never know what a
deal of trouble they have had. ‘Their rate of flow is prob-
ably even now being accelerated by the lowering of the
eastern border of the central plain.

/

REDUCTION OF CONCENTRATED SULPHURIC
ACID BY COPPER.

BY CHARLES BASKERVILLE.

In a previous communication! the writer noted that ;
copper was acted upon by concentrated sulphuric acid

tThis Journal, 17,90.

edt. 84 sp. gr.) not as at the ordinary temperatures of
: ‘ the air, 20°-30°C., but at zero as well. Andrews! states ER
_ that the assertion is incorrect and that it does not occur.
9 } until the temperature 86°C. has been reached, or a point — a
_ above the dissociation temperature ot the concentrated — ae

>

% sulphuric acid, 67°C. according to him. Andrews fur- 1 eS
ig ther says that the author’s statements were based ‘‘not | .
~ upon the demonstrations of the formation of sulphurous :
is _acid, but solely on the formation of copper sulphate,”’ an |
_ which, he says, occurs only “‘in consequence of the pres- ae
3 ence of the air.’’ It is to be regretted that Dr. Andrews
_ did not note carefully the statements of the author in his |
: previous communication, as no reason whatever exists for re.
4 any such,conclusions, because it was distinctly statedthat at
: _ not only the copper as sulphate, but as sulphide was de- oo
termined, as well as sulphurous acid, and moreover, that
_ the experiments were carried out when the air had been ‘i
replaced by a neutral gas, either hydrogen or carbon di- “N
oxide. oe

The author, although confident of the correctness of |
_ his former statement, carried out further experiments*to
correct the error, if committed or to establish, beyond
question, the fact that concentrated sulphuric acid of 1.84
sp. gr. is reduced by copper below 86°C., the limit fost-

tively set by Dr. Andrews. 1 ae
The fact that these experiments but confirmed the for-

_ mer statement of the author allows the incorporation of
-» of the results in this paper. Vaan ae
As far back as 1838 the fact that copper isacted upon >
Fe, by concentrated sulphuric acid at ordinary temperatures, a fi
if sufficient time be given, was made known by Barruel?. © pare
Calvert and Johnson,* however, failed to obtain anyac- a

© tion below 130° C., and considered that none took place. ican
. oh ea

i J. Am. Chem. Soc., 18, 253. | et

2 J. de pharm., 20, 13, 1834. Bete Ss

3 J. Chem. Soc., 19, 438, 1866. ; ! Ae

ve iat
Se Wa gay
Meher, i

te : Hy
Rats statis’ tad ston Bes ais ate os ree eke
OBE We acter aad ine mn |e Md of ee
rn a ee ve fh " Wm Sa He ees ee Hi % Pes Posy
ae & | “JOURNAL. OF x Se
Paya Si tie %

nN

ey even still lower) upwards.”

that time not only were there white crystals of an-

without reduction of the acid. The reaction must take aa

. ygen By only Panter submersion or the bubbling of. the

"Pickering? bere stated that “sulphuric aide ‘atts a cks
_ copper at all temperatures from 19° C., (and probably 5

First Experiment.—Copper ribbon in strips, 1 x 34
cm., was submerged in concentrated sulphuric acid ina ¥
clean glass stoppered flask fora month. At the end of .

heed
~
~

hydrous copper sulphate clinging to the sides of the con- a
taining vessel, but there wasa very appreciable amount of

brownish black cuprous sulphide and sulphur dioxide was | =:

easily detected by its strong odor when the vessel was 4
opened. ei
Andrews? states ‘‘that in the presence of air sulphuric. Y
acid is attacked by copper at ordinary temperatnres, but rt
‘

place according to the equation,
2Cu+O,+2H,SO,=2CuSO,+2H,0.

Formerly the author* stated that the @presence of the
oxygen of the air when it comes into contact with the
copper in the acid has great influence on:the reaction.
Fifty yearsago, Maumené*® proved that when acurrent of
oxygen gas was passed through the boiling acid, the
amount of insoluble residue, e. g., cuprous sulphide, was
diminished, that is, less than there would be formed if |
the experiment were carried out with a current of carbon
dioxide. The copper must be directly opposed to the 0X x

ina idined space, not at all in contact with the copper, | :
but: separated by a thick layer of concentrated sulphuric a
acid, has little or no effect. a

Yet grant that the oxygen of the air (vélitiae of air

1 J. Chem. Soc., 'Trans., 1878, 113.. d
2 J. Am. Chem. Soc., 18, 252.

3 [bid 17-912.

4 Am. Chem, Phys, 1846 [3], 18, 311,

about 200 cc.) confined in the flask, had been utilized in
_ the formation of the copper sulphate produced. Accord-
ing to the formula given above; the oxygen would be ab-

sorbed and no corresponding amount of any other gas
would be eliminated; consequently there should a greater |
external pressure at the close than at the beginning of
the experiment. When the smoothly fitting glass stopper
was removed, not only no extra external pressure was
noticed, but in'fact a pressure from within. ‘This was
evidently produced by the sulphur dioxide generated.
The sulphur dioxide was swept out by a current of air
through a dilute solution of potassium permanganate,
which was quickly bleached. ‘The presence of sulphur

- dioxide was turther proven by the addition of barium

chloride to the bleached potassium permanganate solu-
tion. Nor does the formula given above account for the

_ cuprous sulphide which is always produced.

Second experiment.—Realizing the possibility of some —
organic matter or dust remaining in the flask, although
it had been carefully cleansed, the first experiment was
repeated with the greatest precaution to ensure the ab-
sence_of dust. The flask was scoured with boiling’ con-
centrated=pure sulphuric acid containing potassium bi-
chromate and carefully cleansed with distilled water.
The last jtraces of water were removed by four subse- |
quent washings with the same kind of concentrated acid
used throughout the experiments. The experiment was
carried out in the same manner as the first, the same re-
sults being obtained.

A blank experiment was carried out at the same time.
The. ‘flask was rendered dust free in the manner just
mentioned and fifty cc. of the same acid allowed to re-
main in the flask for six months. At the end of that
period not a trace of sulphur dioxide could be detected in
the blank, therefore the sulphur dioxide produced when >
the:copper was inserted could not be due to the reduction

Sof the sulphuric acid by an extraneous substance, but

ELISHA MITCHELL SCIENTIFIC SOCIETY. PH ee

‘Gee ee | JOURNAL OF THE t

NN.

nary temperatures, 20°-30°-G:

Third experiment.—An ordinary Kjeldahl digesting

flask was made dust free by the treatment noted above.

100 cc. sulphuric acid, 1.84 sp. gr., were placed therein —

and clean dry strips of copper ribbon were completely

- submerged: in the acid. Now air-free carbon dioxide was
passed through the flask for three hours. The inlet.

tube was just dipped into the acid. The, flask was then

attached to a suction pump, with a sulphuric acid drying
flask intervening to prevent a possible return flow of gas —

or air which might carry muisture or dust into the flask.
The flask was exhausted of the carbon dioxide present
for three hours at a pressure of 150 mm. It was then
sealed with the blast lamp and placed aside in a darken-

ed cupboard. Observations were made every few days to

note any reaction taking place. Within two days it could
be easily seen that copper sulphate had been formed and

the liquid was somewhat clouded by very finely divided

suspended cuprous sulphide. Continuea observations ex-
tending over a period of seven weeks showed only an in-
crease in the amounts of both of these substances. =, 'The
temperature of the cupboard had at no time risen above
20° C., and was for most of the time much lower. The

flask was then opened as any other sealed tube, and in-
stead of an external pressure inward, which had been

sufficient to heavily dent the tube in sealing, there was
a strong internal pressure outward. The gas evolved
was sulphur dioxide, easily detected by its streng odor
and bleaching effect upon a dilute solution of potassium

precipitated by barium chloride. AJ1 solutions and ap-

paratus were proven to be free from traces of sulphur di-—

oxide and sulphuric acid by a blank experiment.
Conclusion.—Concentrated sulphuric acid, 1.84sp. gr.,

solely by the copper. ‘The conclusion is that ‘eal phir ig
acid is reduced by copper when air is present at sia: ordi--

Cd

permanganate. ‘The sulphuric acid produced by the oxi-—
dation of the sulphur dioxide by the permanganate was:

Rly? :
ent

29

Be. is reduced by copper when air is absent and at tempera-
_ tures far below 86° C., in fact at the ordinary atmos-
pheric temperatures with the formation of copper sul-
phate and cuprous sulphide and the production of sul-
phur dioxide.

Finally.—Apparatus similar to that made use of ‘yas
Andrews’ with the modification of having three drying —
flasks containing concentrated sulphuric acid instead of
one, and a Meyer absorbtion tube was substituted for a_
single small flask. ‘These served merely as extra pre-

ELISHA MITCHELL SCIENTIFIC SOCIETY.

the outgoing gases with permanganate. Within twelve
hours the permanganate was bleached. Andrews’ exper-
iment lasted only fifteen minutes.
sulphur dioxide produced: was easily detected by the odor
when the apparatus was opened, and in the bleached
permanganate solution by barium chloride. Copper ah
phate and cuprous sulphide were formed. |
Concentrated Sulphuric Actd is Acted upon by Cop-
per at Zero.—Quantitative experiments were carried out |
by the author when the concentrated sulphuric acid in
which the copper was submerged was practically at
zero.” In stating the results, however, the author gave
the temperature as ‘‘0°-10° C.’’ The flask containing
the acid was buried in an ice-bath and the temperature
of the liquid noted by a thermometer inserted through a
_ rubber stopper. The apparatus was air-tight. A stream
of hydrogen gas was continued through the <pparatus in
one experiment for six weeks and in another two months.

going over Sunday, the temperature rose to 10° C. The
temperature could not possibly have remained that high |
for over twelve hours, which would have had small in-
_ fluence when the experiments lasted through a number
of days. The temperature was reported 0°-10° C., how-

1 J. Am. Chem. Soc., 18, 251,
2 Ibid, 17, 908.

{

cautions against dust and insured an intimate mixing of

The presence of the : |

On two occasions when the ice in the bath had melted in

Hort vs
?
s

Sary.

ASO , - JOURNAL OF THE ©
ever. Not only copper sulphate, but cuprous sulphide - _
and sulphur dioxide had also formed.. Copper, therefore, — :
decomposes concentrated sulphuric acid (sp. gr. 1.84)
practically at zero.
From my own experiments and from experiments per-
formed with apparatus similar to that used by Andrews
and under the same conditions, except in regardtothe —
important element, time, which consideration is necessary
for all chemical reactions, the author must adhere to his
former statement.

THE USE OF THE PERIODIC LAW IN
THACHING. :

Read before Am. Asso. Adv. Science, Buffalo, August, 1896.

Only a few years after the announcement of the period-
ic law, when as yet it had attracted little attention, Lo-
thar Meyer pleaded for its introduction by teachers of
Inorganic Chemistry so that something of the orderliness
observed in organic chemistry might begin to appear in-
the study of the inorganic elements. A casual examina-
tion of the text-books of the period and indeed of those
_for a number of years afterwards, would show the great
need of some such system Again the great German
teacher twenty years later appeared before the Chemical —
Society at Berlin and threw the weight of the experi-
ence of these added years and all his enthusiasm in favor
of a thorough use of the periodic system in teaching in-—
organic chemistry. |

Some system must be adopted in teaching this branch ~
of chemistry or the task is hopeless. What will you use Yr
if the periodic system is rejected? Some have answered ~
this by using the old families where the elements are ar-
ranged by chemical analogies. Even in these families —

‘ aay

’ ‘
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roa sted @. a ee ee eRe ba ‘a3

ye: yt veh ] se Nh . peiqe, My
v7) : e ’ 5 1

y —

S bs. npn eiee of the ee law is deeply felt as any one
% eo: can ‘see by examining into their condition a dozen years
a ago and comparing it with the present. Still they are a
4 most unsatisfactory guide to the truths of the science.
more than those same old groups or families. That shows
_ great ignorance, and a most superficial study of the peri-
-_odic system. It does include all that was of value in the
old groups but much more besides.
od The history of the atomic theory is repeated in that of
o" the periodic system. It is now meeting something of the
opposition and even denunciation which the atomic theory
met with in the third and fourth decades after its an-
nouncement. The unexplained exceptions to it are being
magnified and many are inclined to think them insupera-
ble and to look with doubt upon the entire system, while
some are ready to throw it overboard as rubbish past its
. ‘usefulness.
‘ Be Hat think that dn, these classes of opponents will be

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4 found any who have made patient and thorough study of

this system. To me, the more I study it the more its in-
terest and value grows and the more fascinating the
4g search after the great truths which unquestionably lie
within it and of which it yields glimpses even in its incom-
plete state. For the system is incomplete. It cannot
well be otherwise until our knowledges of the science is
broader and deeper. It mail grow with and direct the

_ growth.
But in its incomplete state itis amply sufficient to act

as a most helpful guide to the study of inorganic chemis-
try. It introduces order and clearness where such were

previously, in large measure, lacking. It saves much

useless repetition and so brings about conciseness and
a brevity, a saving that appeals to both teacher and pupil.
q _ There are few earnest students who will not become en-
_ thused with the wonderful symmetry of the science and
hence all nature when this Natural System is unfold-

a

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2 Some have maintained that the periodic system was little -

~

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"ELISHA . MUTCHEE SCIENTIFIC SOCINTY. 31 1. on

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ida to them. I have had a ‘student come By me wit the? of ‘
confession that he had been able to see nothing of the ates pS
tractive beauty of the science in his study of it until this —
system brought law and order into what had only beeen a
confusion to him before. |
The brief time allotted to me gives opportunity only for .

“an earnest plea in behalf of the introduction of the system —

and does not admit of an extended exposition of the ap- —
plication. An excellent guide along this line will be ©
found in the lecture of Lothar Meyer before the German

~Chemical Society which I have already referred to but

let me say that the only truly successful way of teach-
ing this system is for the teacher to make a faithful
study of it and its capabilities for himself. It is not the
old system of families and it is not to be treated merely
as affording a convenient classification. All that was
true in those groups it retains but it further develops

and in a measure explains them.

A few of the lines of usefulness of the system may be
pointed out. First arbitrary distinctions, such as be-
tween metals and non-metals, which have given chemists _
so much trouble to define and maintain, can be done away

‘with. The Berzelian division into electro-positive. and

negative elements is revived and fixed and enables one to
account for the gradations between these elements.

The system gives a simple, easily remembered and ap-
plied arrangement of'valence in the place of the confu-
sion and difficulties of the old methods.

The full introduction of the periodic system means a
consecutive study of the elements as allied bodies. ‘This
in a measure resembles the study of the hydrocarbons in
organic chemistry. It is very valuable as giving a con-
nected view of these bodies. ‘The symmetry of chemistry
is better shown and the student feels that he has a grasp
of the whole, an intelligent ccong1rckers‘cn cf tke picpr-
ties chemical behavior and inter-relations of the elements
which he can scarcely arrive at by the old way.

\ “

a

ELISHA MITCHELL SCIENTIFIC SOCIETY. _ OS aace
Evian i comes to studying the compounds they are _
studied connectedly. Thus the hydrides of all the ele-
ments, are examined, giving their relation to hydrogen;
then the oxides and the influence of the negative and posi-
tive nature of the elements upon their relation to oxygen — a
and hydrogen. Under the head of each acid (for the acid o
largely determines the general characteristics of the oa
salt) the various salts are discussed. This gives a bet- ike
ter understanding of the characteristics, saves repetition bi
~ and tends to fix in the memory the compounds or classes. i
And so too the constant taking up of the elements in their |
groups and series fixes them in the mind. cna
vs I cannot give the system in detail. Study the et * :
system and Meyer’s lecture carefully and then laying
aside prejudices and traditions go boldly to work. What _
I have stated about the advantages of the system may sa
seem overdrawn. The statements are based upon an ex-
perience of three years and no one has the right to gain- ig
say them until he has faithfully tried the system. (oN

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OSOURNAL |
OF THE

Elisha Mitchell Scientific Society.

VOLUME XITI—PART SECOND.

JULY =--DECHMBER.

1896.
{ POST OFFICE :
. CHAPEL HILL, N. ©.

ISSUED FROM THE UNIVERSITY PRESS.
CHAPEL HILL, N. C.
1896.

“Central North Carolina. H. B. C. Nitzer A ae x

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‘Blisha Mitchell Scientific Society.

THE PRESENT POSITION OF THE PERIODIC.
SYSTEM.

The atomic theory, (first announced by Dalton in 1803)
has for nearly a century formed the basis of Chemistry
asascience. It is still the only plausible explanation
of the vast array of facts gathered by chemists of all ages
and forms the web and woof of all modern chemical the-
ories. It has been the object of prolonged discussion and ©
attack, but having withstood the storms of nearly a hun-
dred years, its acceptance now is fulland it has become so
ingrained into the chemist’s conception of his science that
he looks upon it almost as one of his facts, a foundation |
stone of his building and seldom stops to realize that
after allit isonly an assumption, an hypothesis, a theory.
To shake it would sadly disturb the fabric of his science.

A little more than twenty-five years ago with the an-
nouncement of the Periodic Law by Mendeléeff this
atomic theory reached its hiyhest developmentand gaveits
clearest promise of finally leading up to the solution of
the true nature of matter. Like the original theory, this |
development of it received but tardy recognition but the —
sense of its importance has grown until it stands to-day
the central fact of chemistry. Through it new zest has

been given to research in fields from which it was thought

the harvest had been gathered. It has given a new
object to the chemist’s work. It systematizes and arrat-
ges all the facts which he gathers. It gives a compact-

ness and symmetry to his science unknown before. It

brings a step nearer the realization of that dream of the

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- ; es the Unity eo Matter It tay be said with ceatiged
that the Periodic System is the science of Chemistry —
ea tSelt As such it must of necessity be incomplete. as
_ ‘Through it we have been forced to realize how incom-_ |
_ plete our science really is. In one sense, then, to study ©

the present condition of the Periodic System would be to

f

study that of chemistry. We will examine the question, K 4
\ however, from another and more-restricted point of view. "
4 ‘We may, in discussing the present position of the Pe- | ee
__riodic System, draw a distinction between certain points © ia
- which are well established and others which arestill ©
under discussion or beyond our grasp at present. i iu
Mapes First it is clear that the natural arrangement of the NM
elements is in the ascending order of their atomic weights. a
sinh ’This arrangement proveda failure when attempted by ;
Gladstone because of imperfect atomic weights. Inthe =~
. hands of de Chancourtois, Newlands, Meyer and Mendel-

éeff it was developed and the singular relations between the ‘

elements, called periodic, were madeapparent. This brings
- us tothe second point, that when the ‘elements are ar-

ranged in the order of their atomic weights they fall

naturally into certain analogous groups and periods with ™
oe “a recurrence, or repetition, of properties at certain in-
tervals. This leads up to the third point which we may
- acknowledge as fixed, namely that the properties of the
' elements are determined by and dependent upon the atomic
' weights. This was first stated by de Chancourtois, was
proved independently and from a_ different standpoint by
- _ Hinrichs and was forced upon the attention of the world
by the genius.of Mendeléeff. if
Ks The points which still remain to be settled are very
numerous. In the first place the number of the elements
“isunknown. Clarke, in the recent revision of his classic re-
calculations of the atomic weights, givesa list of 74. “This
leaves out of account all whose atomic weights are still
very imperfectly determined or whose existance is still in’
doubt. Mendeléeff’s table allows for the existence of.

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“BLISHA MITCHELL SCIEN LIFIC SOCIETY. PES cP

ee 106 elements if a sub-period between hydrogen aur! it

lithium be granted. Meyer’s table contains 79 spaces,

» or countmg a similar hydrogen period 86 in all. Tf ©

helium and its mysterious companion really have the two
- atomic weights assigned them, the assumption of this —_

é hydrogen group wili become necessary. If Mendeléeffis

' right, then not more than three-fourths of the elements _ oy:
@ are at present known tous. ‘The vacant space allowed — ig
= by Meyer for new discoveries is much more reasonable
a and probably not much in excess of the demand of the
near future. ae
_ Of the 74 recorded by Clarke less than one-half have e
_ the atomic weight determined with accuracy to the first.
"decimal place. As Clarke says: ‘‘In most cases even the a
- first decimal is uncertain, and in some instances whole one
units may be in doubt”.
a As the entire arrangement is dependent upon the atpuide |
weights it is manifest that the doubt attaching to those
' in use seriously retards the development of the system. | an
_ Some points of great interest must be left entirely in
abeyance until data for accurate reasoning are at hand.
The atomic weights of the first third of the elements are
among the best known and this justifies the arrangement
of those imperfectly determined. We would otherwise
if scarcely be justified in laying much stress upon the pe-
__ riodic arrangement. Neda
The imperfectly known atomic weights makes itim- —
possible to assign positions in the system to some of the
rare earth elements and certain of those more recently
discovered. If some of the atomic weights assigned those
4 elements at present are even approximately correct then i
_it seems to be impossible to give them their proper places
in any of the more prominent. tabylat arrangements ry eee
the system. |
This matter of the tabular arrangement of the elements
is one which is very far from settled at present. ‘Men-

deléeff offers two arrangements, one in vertical, the other _ “4

t

VE Aut

Day ee JOURNAL OF THE
in horizontal series. They differ widely i in ae impor- .
tant points. Some iarokeks make use of one, some of the ae
other. ‘The Germans and many teachers in Englandand
America use Meyer’s horizontal table. Many other tables — i :
have been proposed but they differ widely from those of
the two great discoverers of the Periodic System and are
generally intended to present and advocate some scheme q
as to the Genesis of the Elements or some other wild and %
questionable fancy. a
Imay be pardoned a brief reference to the table worked q
out by myself and suggested as an aid to teachers. It. o.
_ does not depart very far from the Mendeléeff horizontal
table, but my own experience has proved it to be more :
easily taught and more quickly learned and hence very
valuable for the teacher. It certainly brings out some — a
facts which no other table presents, and when our know- 4
ledge is fuller it may aid in solving some of the puzzles
now connected with the system.
It must be said that none of the systems are satis- 4
factory, all are imperfect and incomplete and must remain
so until our knowledge of the science is itself complete. |
Recent growth in the science has shown the insufficiency
of the older arrangements. The discovery of argonand
helium (and shall we add asterium?), the repeated de- 4
termination of the atomic weights of iodine and tellurium
and of the nearly twin elements cobalt and nickel show- j
ing them to be out of place in Mendeléeff and Meyer tables, 4
have proved surprising reverses to the system after the
brilliant successes of itsearlier history. Inthe first table ;
the existence of new elements had been predicted with an
exact statement of their properties. These predictions
had been marvellously fulfilled in the discovery of scan-
dium, gallium and germanium. It was to be expected
that future discoveries would only strengthen that which —
was already so strangely confirmed. But these new ele-
ments, argon and helium, were not predicted and refuse to
be fitted into the system, as at present constructed, and are a

Gbicther obstinate and refractory. Inthe minds of some
the whole system seems overthrown. Let us have patience
a little while until the light isclearerand both systems
and these elements are better known and_ wnderstood.

"Society (Ber. d. Deutsch Chem. Ges. 30, 19) ‘‘His erscheint
» nicht ausgeschlossen, dass die Entdeckung der beiden
neuen Hlemente Argon und Helium Anlass zum weiteren

_ . ischen Systems geben wird, wobei vielleicht auch gewisse,
jetzt noch vorhandene Unsicherheiten und Widerspriiche
ihre Lésung finden werden

"puzzle. From the very beginning no logically satisfac-
_ tory position could be nor has yet been assigned to hydro-

true, but they are not satisfactory and su the standard ele-
ment, in some respects the most remarkable and important
of them all, is without an abiding place in the home-of
_ its brethren. It would seem to be the play cf Hamlet
with Hamlet left out.

That these tabulations of Mendeléeff at Meyer are
regarded as imperfect and unsatisfactory is shown by the
__ large number of tables suggested within the last decade.
q Reynolds, Reed, Flavitzky, Livermore, Tchitcherine,
Wendt, Wilde, Preyer, Deeley, Traube, Thomsen, de
_ ~- Boisbaudran are some of the names connected with these
tables. They serve to show that many minds aré attack-
» ing the provlem and give much hope for the future. If
the clear, pellucid truth can be filtered away from the
wild and fanciful and false the progress will be more
rapid.

Our little systems have their day,
They have their day, and cease to be.

So far, no really good method of graphically illustra- —
; ting the Periodic neat has been suggested. The spiral

». Ausbaun, wenn nicht zur Umegestaltung, des period-

gen. There have been sundry attempts at doing this, it is’

"ELISHA MITCHELL SCIENTIFIC SOCIETY. aa

As Winkler recently said before the German Chemical

_ It must not be forgotten that these tabulations. began
their existence with a serious blot upon them, an unsolved.

+

of “ 2 x afi o ' - | ‘4 y ’ oy C : ~ ? ae / ; + ‘ me Hate ny
a9. _ JOURNAL OF THE , Ba 4 a

used by de Chancourtois in his really rémiarktole work iy
has been the favorite method of illustrating tt. <a has. 4
been followed by Lothar Meyer, Mendeléeff, Gibbes, i
Baumhauer, von Huth, Carnelley and others. Probably” a
a better method for class and teaching purposes is the | Pi
- pendulum-like diagram of Spring, used also by Reynolds oe
-and Crookes. Mendeléeff’s objection to the curves of |
Lothar Meyer seems to me valid though many prefer —
to use these or similarly constructed curves. They —
are, at any rate, scarcely suited to the needs of ~
the student who is indifferently equipped with math-
ematical ideas. ‘Two objections can be raised toany and
all of these diagramatic illustrations. In the first place af
they fail to bring out some of the important conceptions —
of the system, even obscuring some of the points; andin ~
the second place, they generally include fancies and spec-
ulations not essential to this system and not justified hy
our present knowledge of it. They go too far and like
much teaching of science by analogy, are lable to be
presented by those using them without due care and pre-
caution. ‘This is especially the case wherever theyare
looked upon as illustrating the genesis of the elements, — ;
about which we still know nothing and should say ~
nothing. 4
Hartley puts the matter in this way. ‘‘The Periodic 4
Law can then be thus stated: The properties of the
atoms are a periodic function of their masses. “Inany
eraphic representation of the periodic law the fact that
itis upon the mass of the atoms that their properties
depend should 2ppear prominently. The diagram of Dr.
Johnstone Stoney used to illustrate the ‘‘Logarithmic
Law of Chemistry”? has, on this account, alone a pre-
eminent importance.’’ This diagram of Dr. Stoney’s could
scarcely be used by the average teacher because of its —
complicated nature and the knowledge of mathematical
operations required. Surely the greatest requirement is
clearness and simplicity. It should appeal readily to the

Ce eee

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| ELISHA MITCHELL SCIENTIFIC SOCIETY. 40

a yee At
d eye te carry in itself in great measure its own explana-
: some portion of them merely. It should not lead to con-
_ fusion of thought, nor to erroneous conclusions, nor to un-
- confirmed dreams and fancies. It is manifest that in the
present imperfect state of the system no such diagram is
- possible. Of all which have been offered I do not know
- ofa single one whichis truly helpful, which has not upon
it some serious blemish, and sol would give voice to
_ a warning against their use. Some one of the tabula-
; tions must serve our purposes for the present as a means
of graphic representation.
; While it is true that the PeHlodic System has not told
us how these simple bodies which we call elements were
a generated nor from what they came, while it leaves for
y the present the so-called Genesis of the Elements a blank
a and may never contribute anything to raise the vail, it is
_ still true that the System has done much to strengthen
the belief in the Unity of Matter and to prove beyond all
> doubt that these elements are not independent, discon-
- nected units but strangely related and interwoven parts
_ of one symmetric whole. However powerless we may be
\ to decompose these simple bodies and split them up into
components, it is becoming every day clearer that they ©
» are not truly simple but compound. Of what composed or
how, we know not, but through them all there runs the
_ traces of some community of nature. Chemists, in their
conservatism, areslow toacknowledgeachange in belief, so
radical as this, without strong bases of proof, either di-
rectly or indirectly experimental. It smacks strongly of
the baseless fancies of the early alchemists and the Science
-cannotaffordany more Will-o-the-Wispchases. But when
‘such great names as those of Wislicenus, Thomsen and
our own Remsen lend their weight and influence to the
“new movement we can follow, using the same caution as
our leaders. ‘To quote Remsen ‘‘It has been shown by a
ax ussian chemist, Mendeléeff and at the same time bya

tion. It should present the details of the law and not ~

noticed by Dumas and Cooke and have fascinated and be- 7

arrange them all in one table, in which they forte pate ,
of a system general. The law governing the variations —
in properties of the elements is known as the Periodic —

Law. The limits of this article will not permit any de- _ e
tailed explanation of this remarkable law. ‘The main :
point that I wish to emphasize is, that the so-called Ma
elements are shown to be related to one another and it
seems impossible in the light of these facts, to believe —
that they are distinct forms of matter. It seems much_
more probable that they are in turn composed of subtle
elements and it has been pointed out that all the substan- 3
ces which we now call elements, of which there are —
about seventy, can be conceived to be made of two fun-
damental elements combined in different Proporyoasea
here does not, however, appear to be any immediate —
prospect of discovering these fundamental substances.” |
The Periodic System is giving us a clearer perception ~ 4
of many things and gives promise of a deeper insight into |
the nature of matter. Yet there are unsolved mysteries —
connected with these numbers which the chemical world ~
has been puzzling over for nearly half-a-century. Whatis |
the meaning of the group-differences and the strange recur-
renceof certain difference numbers and factors which were 4

a
Se
4
‘a
wae

wildered a host of others since? Why should the num-—
bers eight and eighteen be so frequently repeated in ~
these differences? ‘Thus we find sixteen as the interval —
between the atomic weights in the alkali, alkaline-earth, ©
oxygen and other groups (using the old designations).
Why should seven be the number of elements in a period?
Is there a great law of octaves running through nature, |
in music, color, and the elemental ae bodies? Thea

ia

regularities Bieta it has ae a seductive field. he

/

ELISHA MITCHELL SCIENTIFIC SOCIETY. 42

tle is to be gleaned fromsuch work. Strange and puzzling
_ figures occasionally appear but the fanciful erratic na-
ture of most of it can be seen from the connection reduced
by some between these numerical regularities and the plan-
etary distances or other matters, equally as far away.
Some have sought out mathematical formulas by which the
atomic weights might be calculated but without very
gratifying success. One of the most persistent dreams
of the century, Prout’s Hypothesis, seems to have received
‘its quietus for a time at least. Such error is hydra-head-
ed and one can never be sure that all the heads are off.
_ A grand service has been done Chemistry by the dis-
covery and announcement of this system. Chemists have
the short-comings of their science brought clearly to
their notice and research which was before somewhat
_ desultory and aimless, a little picking here and there, 1s
concentrated and direct so that the work may tell. And
this is well as we enter upon a new century-——one whose
close is to see us a good hundred years further on than
. we are now. ‘The gaps must be filled,error eliminated,
knowledge perfected, so that we need grope no longer but
) may walk in the light of truth. The man who takes

yh

some little portion of the field and examines the inconsist-
ent statements, and stumbles over the absolute errors,
and loses his way along paths upon which research ‘has
shed no light at all, must bow his head in shame at the
small result of our toil during all these centuries of grop-
ing.

Let us then be up and doing. Strive to make some,
one thing clearer, to brush away some error, or to place
one stepping stone securely for the feet that are to fol-
low.*

x *Address before N. C. Section Amer. Chem. Soc., F. P. Venable, Ra-
' leigh Feb. 22,1897. .

NOTES ON THE EXACT COMPUTATION OF

THE QUEEN POST TRUSS.

The Queen Post Truss is extensively used in the con-
struction of ordinary highway bridges, as on account of
its simple details it is easily constructed by the average
carpenter. As usually built by him, there are no coun-
ter braces in the middle panel, so that for an eccentric
load, the stiffness of the chord has to be depended upon
to transfer part of the load toeither abutment. Plate 1
represents a bridge composed of two Queen Post trusses

placed parallel to the line of road and sixteen feet. apart

in the clear. The ends of these trusses rest upon wood-
‘en timbers (wall plates) at either abutment and the long
vertical rods hold up the suspended beams which extend

under the bridge from truss to truss. ‘The joists which
. hold up the planking of the roadway are placed parallel
to the trusses and rest at their ends upon the suspended

beams and the wall plates. Any load which comes upon
the planking is transferred by these joists, acting as
beams, to the suspended beams and wall plates. ‘The
load thus transferred toa suspended beam is carried. to
its ends and thence by the vertical rods to the upper
joints of the truss, whence it travels down the rafters or
main braces to the abutments. Fora uniform load over
the bridge both suspended beams carry the same loading
and the computation of the stresses in the truss members
is made in the usual manner. If, however, a heavy con-
centrated load, as that due toa road roller or a crowd of
people, is supposed to act on only one suspended beam,

the investigation is of a different character. The part of

this concentrated load which is held up by the vertical
rods, meeting at an upper joint of a single truss, will be

ei ees a

4a
4t

?
.
-

-
>

lta i Rae re ile
- a

we eee Oe ee eee ee ee ee ae
7 ; a : — De : ee
.

ELISHA MITCHELL, SCIENTIFIC SOCIETY. 44

called W. At the upper joint, this vertical load W is

_. decomposed by the parallelogram of forces method into

components acting down the main brace and along the
upper chord respectively. The resulting push along the
upper chord is decomposed at the next joint into compon-
ents acting along the other main brace and vertical. The
triangle of forces at this second joint is necessarily the
same as that at the first joint, as the horizontal com-
ponent is the same and the rafters are equally inclined to
the vertical. Therefore the stresses in the vertical and
rafter at the second joint are precisely the same in char-

acter and amount as at the first joint. Hence there will

be a tension W, in the vertical rods at the sécond joint

and this tension, pressing the suspended beam upwards

against the lower chord, tends to bend it upward. The
lower chord is thus in the condition cf a beam of length
equal to the span and subjected to a single upward force
W, acting at one third of its length from one end for equal
panel lengths. The force W, causes the lower chord to
press upwards against the feet of the rafters, with a force
2W at the nearest rafter and 1W at the furthest. As we
found the vertical component of the stress in both rafters
= W, acting downwards, the resultant pressures on the
abutments are, W—2W=1W and W—1W=2Was should
be, by the law of thel_ver, for the original load W acting
at the first joint, the larger reaction occurring at the
abutment nearest the load. — | |
The lower chord must be made of sufficient dimensions |
to act as a beam to safely sustain a vertical force W act-
ing upwards and placed a panel length from one end. The
moment is greatest at the force and equals 2 W (its re
action at foot nearest rafter) multiplied by one-third the
span or length of lower chord from foot of one rafter to
that of the other. In addition, the section of the lower
chord must be made large enough to provide for the hor-
izontal component H_. of the stress in a rafter at its foot.
This thrust generally acts at / inches above the center of

ee OUD bn UA JOURNAL OF THE

beams, the stresses in the verticals are W as before. So that
_the stresses in rods, rafters and upper chord are precise- _
_ ly the same as for the eccentric load first considered. In

7
7 PS
7
/
;

the chord, depending on the Aone of the Hetey heen ihe. ce.
rafter j joins the chord, and thus not only causes a uniform
stress, in the chord but one due to the moment HA. The ie
maximum fibre stress in the lower chord at a panel point
is that due to the abeve forces combined with that dueto
the weight of the chord, for all of these influences cause
tension in the top fibre of the chord at a panel point. 1

With a full live load W at each end of both suspended

this case, the stress in the vertical rods =W, is exactly
balanced by the load W held at foot of rod, so there is
force tending to bend the chord. ‘The dead load stresses
are of course to be found and added to those caused by
the live load, 7 .

The above theory is upon the supposition that the
‘‘suspended beams’’ are not fastened to the lower chords. /
If they are fastened, a load at one suspended beam only,
is partly carried by the chord ‘‘acting asa beam’’ and
partly by the vertical tics. Reasoning as before, the
stresses in the verticals at the other joint are the same as
those of the first, giving an upward pull on the chord
where the suspension beams meet it. The lower chord
in this case, is bent ‘downward at the load and upwards
at the other panel points, thus giving a reverse curva-
ture to the chord, so that it can resist bending much ~
more effectively than in the former case, where it was,
compelled to act as a beam with aspan equal to the span
of the bridge and was acted on by a full panel load. The
exact solution for this case cannot be effected by statics
alone. Another principle has to be made use of and I have
availed myself of the ‘principle of least work, for which
see an article by the writer in the Transactions of the
American Society of Civil Mngineers for April, 1891.

In this article, the writer deduced the principle of least —
work, with effect of temperature changes included, by

: ak
; , : te ‘ -, wove af
4 Eg - om ar Sm S 60 Sin! aos
Pe PS ee LT A ee Se oe

“ELISHA MITCHELL BE et SOCIETY, 46

eS

a the method of virtual velocities, to which it Fenny lend
itself. Castligliano in his ‘‘Systemes Elastiques,’’ a work

that deserves to become classic, had already deduced the
principle in an entirely different manner and given nu- ~
merous applications to structures in metal and stone.

The writer has followed essentially his manner of ap-
plying the principle, to the truss next to be examined, |
though by regarding the chord, when acting as a beam,
to be ‘‘free’’ under the action of certain forces. there is a
gain in simplicity.

I have computed in full, the truss shown in plate 2,
an inverted Queen Truss. As it corresponds exactly in
theory to the truss shown in figure 1, if we suppose the
suspended beams there to rest on or be fastened to, the
lower chord, the solution of the one truss will indicate
that of the other. |

Reference will be made to the following principles in
the theory of elastic work:

Ina straight bar of length @ and cross section y, sub-
jected toa gradually applied stress which reachesits max-
imum s, the elastic work of deformation, e being the co-
efficient of elasticity of the bar is,

1 Bee:

2 ew |
In a beam subjected to vertical external forces, if we
call the length of a segment of the beam 2/ and the mo-
ments of the external forces, at the right end of the seg-
ment M,, at the middle M, and at the left end M,, the
elastic work of deformation, of the segment considered is
1 Caer
Meee i CIVIC AVM 2 ot NEE Vl Oo
OHS
K, being the modulus of elasticity of the beam.
The principle of least work requires that the sum of
the work due toall members of the Structure shall bea
minimum, when one unknown stress is required.

i? ™ ree r eet a Ae’ ee oN el VV T 4 LAD 8, Hd Viet 7 URAL PT PAY
\ : ee 4 . ( Ta iat ,
ner’ ® ? x oie | ; .f 7 , Am An
© ‘\ nf ath | WEN NAL in
d : Aa *y f p j
, f Wy 4
‘ 7+ ‘
/ ° .

47 | JOURNAL OF THE

In the elevation of one truss of the structures SHown

by fig. 2, the centre line of chord is 45 ft. long and is di-
vided into three equal panels. From centre line of chord
to bottom of posts is 4 feet, thus giving the length of
inclined rods AC (from washer to foot of post) 15.52 feet

and the length of horizontal rods CC 15 feet.

We shall suppose that the two suspended beats on

either side of the left post, transfer to the chord through
the hangers, a load of 14 thousand pounds and the sus-

pended beams at the right post similarly transfer a load

of 4.5thousand pounds. [All loads, reactions and stresses
will be expressed in thousand pounds. ]

Call f the part of the load 14 that is supported by the

chord acting asa beam and therefore 14— will be the
part held up by the left post. The downward thrust of
the post on the ties gives a stress in the left inclined tie
=15.52(14—p)=4 and in the horizontal tie, 15(14—4)+4.
This last tension, when resolved at foot of right post into
components, gives a tension in inclinced tie there and
compression in post, the same as found at the left apex
C, the triangles of forces being equal at the two apices
as the stress in the horizontal tie is the same in both.

The right post thus pushes upwards with a force
14—4, which is assumed, as we shall find it to be, great-
er than the load 4.5 applied to chord at right post. The
difference (14—4)—4.5 = 9.5—4 represents then, the up-
ward thrust against the chord there which must be sus-
tained by the chord acting as a beam. .

The chord acting as a beam, therefore sustains a
downward force over left post of # and an upward force
at right post of (9.5—A). By the law of the lever, these
forces cause a downward pressure at the left abutment
of (AG—3.166) and an upward effort at right abutment
equal to (6.333—).

As the vertical components in both inclined rods are

each (14—p) we have, as the total pressure of truss on
left abutment, (A—3.166) + (14—p) = 10.833 and at right

ELISHA MITCHELL SCIENTIFIC SOCIETY: 48

abutment (144)—(6.333—f) = 7.666, just as we should

find for the two original loads by the law of the lever.

These results are true for any value of A(< 14) that
may, be assumed. They do not determine f. We shall
soon see how to determine it after expressing the work
of deformation of the entire truss in terms of A.

As the elastic work in the vertical posts is very small
it will be neglected. The work in the ties 1s given by
formula '‘(1).

For the two inclined ties, the stress, s=15.5 x (14-9) ~
+4, a=15.5 and w=.04 square foot'nearly. Substituting
these values in (1) and multiplying by 2 we get the elas-
tic work by inclined ties at either end.

Similarly the stress in the horozontal tie CC, s=15 |

(14—A)+4, also a=15 and w=.04. These values substi- ©
tuted in (1) gives the work of horizontal rod CC.

As the modulus e is for iron and E for wood, take
e—16 EK, then the work ot the iron ties in one truss will
add up to,

1
—(1075/’—29600))..............++22+-(1).
2K

* on neglecting terms that do contain , as will be done in

what follows, as snch constant terms disappear when dif-
fertiated as to #. |
To ascertain the work on the chord acting as a beam,
we use formula (2). We have the downwaad force # act-
ing at left post, the upward force (9.5—) at right post,
the upward reaction at left abutment=—(4—3.166) and
the downward reaction at right abutment—(6.333—4).
The beam can thus be considered as free and subjected toe
these forces only,
Let us apply formula (2) first to right segment of
chord from E to B, 15 feet in length,
id fee Sop
M, = 9,
M, = (6,333—)7.5,

Oi A= re, 336A) 15; : ei.
- me * ging the work of deformation for this section, me) e
eS bee ee (1125 pg? —14250 aio
‘ ; i ae 2K 1 ‘
_ neglecting the constant term as before, ‘For the midate a
_ segment, 2d==1 5, |

ea M,=(6.3333—4)15 a ae .
ae M,=(g—3.166)225—7.5f SUNN

he — M,=(p—3.166)15 eee
‘a The work by (2) for this segment is therefone, | Pe t
a6 ; 1 oh a

BES Bids Sh (3875 p* 320680) lw ps a ee (5). Ss
oe ORI a ce

' Lastly for the left segment A B, 2715,
hae M,—=(p—3.166)15 Na ae
Bet, 2 M,=(4—3.166)7.5 ee
ye M,=0 ae
* a by (2) work equals 5 :
ae : es
nt — (11 25p'— 7125p) io ee
Re 2K1
Adding together (4), (5) and (6) and fora beam os 16 a8
inches, get g
ae vee Ae). aes a
We get as the total work of the chord acting. asa.
2 Dea, | . ee 2
Bie ef | : 1 a
es —— | 569532°—541050A | .... ee ee eee eee 9
pronase ) | a

! A The uniform compression in the chord, s= 15 are *
)) 4, causes eee work given by (1), on substi tuting, x >
a=45 and w=} square foot; the amount being, +

1 f | : Ree i
——— | [950f°—266004] |. -.- 2. 622 - pyy hee se
aK | J ne

~

ELISHA MITCHELL, SCIENTIFIC Socm ry. i 150°
On adding the expressions (3), (7) and (8), we find

for the total elastic work of one truss, neglecting con-
' etants,

“hg |
— | 1589608 + 50725081, Ay Rey an Me LC? ||
2K | ) | |
By the principle of least work, the derivative of this
with respect to # must be placed equal to zero in order to
find p.

x
b
-
a 4
De
.
sh
- *
an
#
ct
a
S,
_~
,
_

117920A4—597250—0
H=5.08:

So that the chord, acting as a beam, sustains a down-
ward force at the left post of about 5 thousand pounds
and an upward force at the right post of 9.5—4 or about
4.5 thousand pounds, causing the chord to bend down-
at the left post and upward at the right post. This
reversed curve assumed by the chord causes it to be more
efficient as a beam than in the preceding bridge exam-
ined.

The value of the reactions of the chord, acting asa
beam, at the ends, we have seen to be,

— V eS ee ayer et oer ee it
. p Si os a fy

SO ae tee EE Ere

p—3.17=1.90 and

q 6.33—p=1.26;

4 thus giving the greatest moment at the left post equal to
= 1900 x 15=28500 foot Ibs.

4 If we allow, by the usual formula, 1200 pounds per
square inch fibre stress the chord, for a depth of 16
. inches, should be 6.6 inches wide in place of the 6 inches
3 assumed. Certain changes of temperature will increase

this width still further as we shall see.

INFLUENCE OF CHANGE OF TEMPERATURE.
=
‘The linear expansion of iron, per unit of length, for each
degree centigrade (1°C), is 1+82500.
Suppose the bridge put together at 10°C (50°F) and that

the oleh sebwivds rises oe a pee: f
“a expanded horizontal bar CC is supposed in position, 3
a ie end bars A C and EC will each be too long by

SS ae Wa ba J 155 O0 te
Saas : 2 Se SOS Ot aera ak ;
Bye AY 2 82500 82500.

wees | ;
_. where 7 = angle that end bar m kes with chord.

ae ‘The tension in end rod or tie is

{Ne Aen , .

Rian a 15.514) 4 ;

Oat

sae ee Twice the product of these two expressions, or,

eae ~ (constant—.002142) 3 ies
wey as ‘ ag
pera gives the work due to heat in the truss, neg lecting any 4
nk fe ; ~ : can
expansion of the wood. A
ish anas

Bots %, By the article of the writer reterred to above (Scetions a
. 6) we must add this term to the elastic work (9) of. the — ia

os entire truss and put the derivative with spar to ee ne
agen equal to zero. Doing this we obtain, ape
a 58960—298625—.00214/ =0. ee
: If we assume E for yellow pine, 1, 600, 000 Sone per a
si Sq. inch, or, as we must substitute it here, where all.
es dimensions are in feet and loads in thousand pounds, Be
bis E=230400 thousand Ree per sq. foot, . ee
we derive, : eg a
: 58960p—298625—493¢=0........ (10), a
whence for 4=+25(C), ie 5, 27 + a
and for ¢=—25(C), p=4.85. an

The rise of temperature of 25°C (45°F) above the supe a
posed normal of 10°C (50°F) gives the greatest reaction, — Re
- 2103: pounds, at left abutment, and hence the greatest —
)- momemt = 2103xX15 foot pounds at left post. Ta
- moment calls for a beam 7.4 inches wide by 16 deep. It “

was made 8 inches wide to allow somewhat for the uni-— 4

form compression, which, however, is less than 300

~ pounds per square inch on account of the large section of — oe:

the chord. At the left post, the weight of the chordal a

,! ei

he pi a a as Taty Asi) itt en pa ny ee a
Mee Ue A COME Ul ak
Li i? 5 cy 4 + a ae 4 ate |
Aa) ioe ee Nat bs Cen
wet > ¥ 5 my wy o~
«e 4 P

tends to cause tension in the upper fibre. Its influence
being beneficial, was not further regarded.
The method has now been given in full for ascertain-

ino the stresses in the various members fora non-uni-

form loading.
\In this particular case, the dead load per panel per

a was assumed at 4500 lbs., which is found to be

nearly exact on making out weights, etc.

The live load was assumed to be that due to a crowd
of people. weighing nearly 80 lbs. per sq. foot, for a
clear width between trusses of 16 feet: the portion held
at one apex of cne truss being 9500 pounds. As sucha

~ partial load can only be obtained by stipposing the live
load to extend from an abutment two panels and then.

neglecting the part held up at the farthest apex, it is in
excess of any eccentric load that can be placed only at
one apex und thus is on the side of safety.

The influence of temperature changes is seen to be very |

marked for this combination bridge and would be stiil

“more pronounced for more northern latitudes, where

greater ranges of temperature are experienced than in
the Southern states. By giving any desired value to ¢ in
equation (10) above, the resulting value of Z is readily

found and the chord examined as before for proper width.
It would materially tend to obviate the bad effects of »
temperature if the truss was assembled in the heat of |
- summer without any camber in the chord. As it became
colder, the chord would receivea slight camber upwards,
-- which would increase with the fall of temperature, and

thus tend to diminish the large bending stress in the chord
at the most heavily loaded apex. For this case, we should
put, say, 7 =—50 in eq. (10) and thus find f= 4.65 and
finally the resulting maximum moment in the chord act-

ing asa beam which turns out to be at the right post

where no live loadis supposed to rest. It is 168315 ft.

lbs., and thus less than for the temperature at which the

ELISHA MITCHELL, SCIENTIFIC SOCIETY. 52

40 miles in width, of metamorphic slates and schists, ~

JOURNAL OF THE
baie is assembled: so that no increase of eiicee iS . expe |
‘rienced, but the reverse and the width of chord can be as
safely taken at 6.6 inches, or say 7 inches, for a depth of coe
16 inches, as first found. ee

The maximum stresses in the ties and posts are ot EY a
jcourse under a full loading of 14,000 pounds at each post. —
The chord now bends downwards throughout so that it.
cannot sustain near as much of the load (acting : asa
beam) as before. The strict investigation can be made ©
as above; but it may prove near enough in determining — 4
the section of the ties (the posts evidently having an ex- a
cess of strength) to suppose each post to carry the full —
panel load in place of the strict value (14—A), to the ties
and proportion them for the corresponding stress in an 4 |
end tie, as their section is uniform throughout. The sec-
tion given was determined in this way for anassumed unit
stress of 10,000 pounds per square inch. | y a

Ke

SOME LATE VIEWS OF THE S0-CALEE a
TACONIC AND HURONIAN ROCKS IN
CENTRAL NORTH CAROLINA.! a

A

BY H. B. C. NITZE. . a

A

The region under discussion embraces a belt, from 8 to 4
extending from Virginia in a general southwesterly direc- 4
tion across the central part of North Carolina into South
Carolina. This area forms the principal gold ore belt —

1For further discussion of this subject and for map showing the dis 74
tribution of the rocks ‘here described, see Bulletin 3 N.C. Geological.
Survey, 1896,

+

Upper Chord )

Lower Chord Renee |

WE YY, MN
Uy) Suspended Beam } 7] kaa ae
[eZ] 7

~

Zee A I

4
vo
I
a
~
wn
v
rg
te
3°
be
e
=
ss

Chord
Suspended Beams is

ant hare | QUEEN POST TRUSS
Floor Plan

_ Plates kindly loaned by Prof. J. A. Holmes. State Geologist.

WAS 27 SE Oa OE 1g Ae A ee =

rp i ee

Suspended Beams
7'x 16"

_ Fig. e.

(dE) Detail of Iron Washer ;

Fig. b.—Side Elevation. Two Rods 1% diameter
# DECK BRIDGE, 45 FEET SPAN. 23 “ | MA Blgias
Side View. } :
zk Detail of Iron Shoe
7 C Ww
A A B DB 2 2 A A 8
A

ele Chord 8"x iG”

‘x 16”

r

16 feet clear width
Planking 3”x 6

spended Beam 7
Fig. c.—Cross Section

Sus

Fe

#¥
ify

Chord 8"x i6” "
Suspended Beam 7’x 16"

x ~ Fig. a.—Ficoc Pian
re OS ER Sere aera ee ae Pla ates. kindly loa | Prof. J. A. Holmes, State Geologist ——

ee eeNy! FM d aM ML LT. ir lial HR rT SCM HP moth Ot Are? Se ae
, al =~ j once ee, oe! ey o,): — x hy ele HY ‘ : > N a
CE mM, A, Se es Ne Ss ; ; X

a “—

ELISHA MITCHELL SCIENTIFIC SOCIETY. 54

- of North Carolina, in which connection it is known as

the Carolina Slate Belt. It includes, in North Carolina,
portions of the counties of Granville, Person, Durham,
Orange, Alamance, Chatham, Randolph, Davidson, Row-
an, Moore, Montgomery, Stanly, Cabarrus, Anson, and
Union. On the west it is bounded by an area of igneous
crystalline rocks, and on the east, for the greater part,
by the Jura-Trias sandstones, conglomerates and shales.

The general term slates and schists, used above, covers
a broad designation. ‘The country rocks of the region
are:—1) Argillaceous, sericitic (hydro-micaceous), and
chloritic slates and schists, all of them more or less meta-

‘morphosed. 2) Sedimentary pre-Jura-Trias slates. 3)

Ancient volcanic rhyolites, quartz-porphyries, etc., and
pyroclastic breccias, often sheared into a schistose struct-
ure. The general strike of the schistosity is N. 20° to
50° E., and the dip is steeply to the northwest.

In 1856, Prof. Ebenezer Emmons, in his Geological Re-
port of the Midland Counties of North Carolina (pp.
38-73) described this region and referred the rocks to the
Taconic system; and in 1875, Prof. W. C. Kerr, \in his
Report of the Geological Survey of North Carolina
(vol. 1; pp. 131-139) included the same rocks in the
Huronian.

In order to gain a more comprehensive oversight of this
important geological area, it will be well to first state
briefly both Emmons’ and Kerr’s conceptions of their
Taconic and Huronian in this part of North Carolina; and
then to discuss the same in the light of more recent inves-
tigations, carried on by the writer during the latter part of
1894, for the North Carolina Geological Survey. These >
investigations were unfortunately of acursory and incom-
plete nature, and can but form the beginning of a more
thurough study of the region lateron. However, they will
well serve the present purpose of showing the errors

into which Emmons and Kerr had fallen, and the miscon-

sti vie < . 3. ‘

ey Hetices, the science of microscopic : paceaph a
D eagily unknown in Emmons’ days, and certainly, ins its
infancy at the time of Kerr. Rerice res. a . .

“

a ne

a : . EMMONS’ TACONIC: SYSTEM IN NORTH CAROLINA. a
Hen mons placed these rocks among the oldest sediment=
Sg ‘ aries, i. e. at the base of the Paleozoic. In his words: | 2
“ee ) The formation of the midland counties, which occupy
~ - the largest extent of ‘surface, are slates and siliceous
rocks, which have been called quartzites.” * * Ves ag
a “The slates are variable in color and composition. — ‘They
it, are mineralogically clay, chloritic, and talcose slates, i
ek taking silica into their composition at times, and- even >:
Bp & ‘passing into fine grits and hornstones, but still va ariable Be
eet in coarseness. In the order in which they lie the talcose rs
slates and quartzites are the inferior rocks, though

ee ~ quartzites occur also in ne condition of chert, flint. or.
oe _hornstone in all the series.’ | Diy a a
‘ava He established their sedimentary origin from the oc- a
currence of numerous. beds SOE IEE in his belief,

ant 4

rounded pebbles. Further, ‘‘I found, however, many —
Be _ beds among them which looked like sediments, were por :
_ phyrized and somewhat changed, though not strictly por- a :
_ phyries. I found after much search too, beds which were as
—. unequivocally pebbly; and finally, to remove all doubt, E s
“was fortunate in discovering that the porphorized beds
ig. also frequently contained pebbles; proving most conclu-- a
. sively that they are sediments which were partially al- a
fae dered?” nk 4
One of the arguments that Emmons used to prove the

— sedimentary nature of the Taconic, and its derivation

- from the basal complex, is the presence of gold in the §

*

‘et 1Geol. Report of Midland Countiss of N. C.
2Tbid, p. 47.

te, J
bike

"ELISHA, MITCHELL 5 SCIENTIFIC socmmry.

a
tah BSc 4

e: Bin bid schists, ‘‘which of course must have heen com- | oh
mingled with the sediments at the time these rocks were
ee ~ deposited. 99 x % * * ‘The cold exists mostly 1 in the io a
oy _ western belt of granite in the veins belonging to the horn-_ ua
® _ dlende and gneiss of the Blue Ridge.’”! ee.
a he claimed to have discovered ix his Lae 3 as

er Taconic sandstones and cherty beds at Troy and Zion :
(12 miles southwest of Troy) in Montgomery county, sev- -
e, eral species of fossils.” He described these as siliceous
corals of a lenticular form, from the sizé of a pea to'two / 7<
- inches in diameter. Two varieties are distinguished and —
named by him: Paleotrochis (old messenger) major and, 4
Paleotrochis minor. The following descriptive section,
in the ascending order of the rocks and beds, in which
these supposed fossils were found, is given: Mea,

‘* (1) Talcose slates, passing into siliceous slates, and 7
which are often obscenrely brecciated. Thickness unde-
' termined. . ree
a | 4) Brecciated conglomerates, sometimes porphyrized. ¥ a

*#(3) Slaty breccia, associated with hornstone. _

(4) Granular quartz, sometimes vitreous and filled with

fossils and siliceous concretions of the size of almonds; ig
two to three hundred feet thick. ee
(5) Slaty quartzite with very few fossils; about ai stat
feet thick. | whi
‘“(6) Slate without fossils; forty feet thick. gia Be .
‘*(7) White quartz, more or less vitrified, filled witht
- fossils and concretions; seven to eight hundred feet thick. :
(8) Jointed granular quartz, with only a few fossils. as a
(9) Vitrified quartz without fossils, and thickness very” ; if

creat, but not determined, oe
‘The fossils also occur in the variety of quartz or eine

a quartzite known as burrhstone, and which 1 is often por- ae
_ phyrized.”’ | ee

1Tbid, p. 57. pe
2Idib pp. 48. 60.

8 Tt MA © } Pee Ae aed ona Salt ar stm.’ . Mind i eat
LE ERP NOs Dna NUCL be APES foe eR oe rk
f Bi (are ei dnt va oy t Dea i | 7
~ ‘aja s+ Me ar Be :
Pye yg / Nye ae IA ORE y Be 5,

Fh iS ; Big Ak
Me sy ee a JOURNAL oF ae 0s Sa eae

These fossiliferous beds~ are stated to be sometimes
auriferous.

He is therefore disposed from the above facts, to plage
all of the rocks not decidedly igneous, thati is, those which

- stratification is but schistose lamination), with the sca :
ments. He then correlates these rocks with the taconic, — a
the infra-silurian sediments of Massachusetts, based main-
ly on ‘‘their lithological characters, and the relationsin
which they are placed to the older rocks, and those which
they sustain to each other.’’ In North Carolina, he says,
these rocks have been derived from syenitic granites, <a
which he believes to belong to the primary or basal com-
plex. He makes two divisions, the Lower Taconic and
and the Upper Taconic, noting that the distinction be-
tween them, however, is less obvious in North Carolina
than in the northern equivalents. |

The Lower Taconic, ‘The Lower series will contain.
‘the talcose slates. white and brown sandstone, or quartz,
which is frequently vitrified or cherty, and the granular

limestone and associated slates.?”’
The talcose slates are stated to be made up of talc and

fine grains of quartz, becoming a friable sandstone when — |
quartz predominates. Color and lustre silvery when —
chlorite is absent, and greenish when chlorite is present.
The following varieties of these quartz rocks are given:*

‘(1) A fine grained coherent quartz.

“(2) A fine grained friable quartz.

‘*(3) A fine grained micaceous and talcose quartz. Ag

(4) Vitrified quartz or chert. (a) green, Blue, (b) aga-
tized. Og

*(5) A cherty or apparently porphyrized quartz, which
contains feldspar, which decomposes and leaves a rough ~
porous mass similar to burrhstone.

1Ibid, p. 49; Ibid, p. 51
2 Ibid, p. 55.

,

ELISHA MITCHELL SCIENTIFIC socinty. 58°

‘*(6)Pebbly and semi-brecciated quartz.

‘*(7) Common brown quartz.

ee tock. 4). Fo 4s Psociated with?) <0. * tale
cose slates. Itis repeated two or three times. grea
It frequently contains beds of pebbles. But its most in-
teresting feature appears in its passage into hornstone,
chert or flint.’’

The apparent vitrification he considers due to a chem-
ical combination of the particles, that is, toa cause inde-
pendent and distinct from heat.

‘‘Acalmatolite’’ (pyrophyllite) is mentioned as occur-
ring in beds in this Lower Taconic series. And lime-
stone, containing talc and tremolite, issaid to be asa |
with slate and quartz,

Emmons’ rocks of the Lower Taconic, then are:'

(1) ‘‘Beds of talcose slates. (2)Quartz rocks with their
alternating series of talcose slaies. Beds of agalma-
tolite. (4) Limestone with its interlaminated slates.

The Upper Taconic. ‘This division of the system 1s
not very clearly marked. * * * In North Carolina
the linc of demarcation is sometimes difficult to define. But
the rocks which I regard at the present time are (in as-
cending order)’:

(1) ‘‘Argillaceons, or clay slates, with many subordi-
nate beds, roofing slates, mountain slate.

(2) ‘*‘Chloritic and argillaceous sandstones, flagging
stones, etc.

(3) ‘‘Brecciated conglomerates.

The ordinary solt, greenish slates may be regarded as
the prevailing mass of the first division. The predominant
color is greenish gray. A red decomposed variety is—
mentioned as being common near Pittsboro, Chatham
county. ‘‘The subordinate beds are fine siliceous ones
passing into chert or pibiheate SAMAR AME OA eral
are blue, DUSDIe. @ and green.’

1 Thid, p. 55.
2 [bid p. 65.

“+
‘

_concretionary and exfoliate in concentric layers.”

_chloritic base. The. mass is composed in the main of

‘called flint, chert and hornstone. Color bluish-black,
- passing to purple, grayish, white and green; sometimes

Pe NEG yak eb: OL ¢ rath
frye Oe a att ; Fs ms “5 i

| oF si tisames oF THE

wwe

division. .
' These beds may be ailsbalien for trap, sth greenish and
* toug h, and besides like trap the broken strata become —

“The brecciated conglomerate has an argillaceous or

fragments of other rocks mostly retaininge an angular ~
form. The fragments are sometimes eighteen inches,
and even two feet long.”’ | be

‘’Theclay slates and breccia, with their intermediate beds -
are traversed by veins of milky quartz. They are some= BY
times auriferous.”’

The so-called quartzite of both the Upper and Lower
Taconic is considered of such peculiarity that a separate
chapter is devoted to its description. It is described as
an uncrystallized quartz, resembling eun-flint, and is also

banded; texture fine when compared with the finest sand-
stone; translucent on edees; fracture flat conchoidal; often
porphyritic, porphynzed; and it is stated that frequently.
the fresh fracture is dotted with small limpid crystals of
quartz. ‘ |
“Phe varieties of quartzite are numerous if color and
texture are made grounds of distinction:! | |
(1) “Light gray and compact, or very finely granular.
(2) “Smoke gray, with grains of hyaline quartz dis-
seminated in the mass. a
(3) ‘*Texture fine granular, with drab color.
(4) **Porphyrized quartzite.
(5) “‘Light ercen quartzite,

1 Ibid, p. 71.

oh ee rete iit Rie peti mea RA a i ARS a
4 ; . : ‘ * A .
ELISHA MITCHELL SCIENTIFIC SOCIETY. 60

“ (6) ** Greenish, and full of cavities, and frequently epi-
fate dotic. ~~ | |

(7) *‘Banded quartzite, or coarsely agatized.

— “These forms of quartzite are not confined to
rocks of a particular age, or to a given series. They
seem to be distributed through-formations of all ages and
epochs. They are common to both divisions of the Ta-
conic.”’

bi Emmons explains their origin from an aqueous chem-
ical standpoint.'

KERR’S HURONIAN SYSTEM IN CENTRAL NORTH CAROLINA.

Kerr recognized five principal outcrops of the Huronian

» rocks. The one that corresponds to the Central Slate
belt, and hence of interest here, is stated to lie on the
_west side of the Raleigh eranite.? ‘‘The bottom beds —
are argillaceous and talcoid.* * Three or four miles

_ from Raleigh these slates become highly plumbaginous,
: ~* * * anda heavy body of micaceous, white, slaty quartz-
_ ites follows closely along the west side of the graphite.
Alternations of argillaceous, talcoid and quartzitic beds
continue for five or six miles, when they disappear be-

4 neath a narrow trough of Triassic sandstones, beyond
5 which they emerge along an irregular, but approximately
j northeast and southwest, line iu the central mineral bear-
z ing slate belt. * * * This tract extends quite across
_ ~ the State ina breadth of 20 to 40 miles, and is composed
of siliceous slates and clay slates chiefly; the former being
often brecciated and congicmerate, the pebbles sometimesa
; - foot and upwards in diameter, frequently chloritic, and
- often passing into hornstone and chert, and occasionally
% into quartzite. ‘The clay slates are generally thin-bed-
ded, often shaly, gray, drab, banded, blue and frequently
greenish from an admixture of chlorite; sometimes tal-

1[bid. pp. 51 and 72.
2 Report of the Geol. Sur. of N. C., 1875, Vol. 1. pp. 181-9,

X

-

615, | JOURNAL OF THE

coid or hydro-micaceous; and very often they may be bet- i

ter described as conglomerate slates, being composed of
flattened and differently colored soft, slaty fragments of
all sizes, from minute particles to an inch and more in
diameter. *. * * * * Jn Montgomery county, ina
very heavy ledge of siliceous slates, occurs a siliceous con-
elomerate, which is filled for hundreds of feet with very
singular siliceous concretions, some of which Dr. Em-
mous has described under the name of Paleotrochis; but
the rock for several miles, as wellas at this particular
locality, contains a multitute of rounded and ovoid
masses from the smallest sizes to that of a hen’s egg:
showing the w de prevalence of conditions favorable to
the operation of concretionary forces. * * * The tal-
cose, siliceous, chloritic slates are more abundant towards
the base of the series, the east side, and the clay slates
predominate on the west.”

He also mentions the occurrence of beds of pyrophyl-
lite, and the abundance of quartz veins. The strike is
‘givenas northeast, and the dip prevalently west at steep
angles. |

‘’The belt is bounded on both sides by the Laurentian,
on which it lies unconformably, and from which its ma-
terials were derived. The stratigraphy therefore indi-
cates the horizon of these rocks to be the Huronian, and
lithology agrees with that determination.’”’

RESULTS OF MORE RECENT PETROGRAPHIC STUDIES.

The Slates and Schists. One of the results of the late
geological work in this belt has been to identify at least
the argillaceous, sericitic, and chloric schists and slates.
with those of Emmons’ Taconic and Kerr’s Huronian.
These rocks are termed schists, and again they are term-
ed slates. Certainly a great number of them have a true
slaty cleavage, while others are more truly schistose, 1. e.
the laminae are not essentially parallel. These different.

1[bid, p. 133,

4

Mae ee

4

at

en
4

re bil Aes 2 apa

2

ELISHA MITCHELL SCIENTIFIC SOCIETY. 62

structural effects are due to dynamo-metamorphic action
on materials of different composition. The argillaceous
types might more properly be called the slates (clay-
slate, thon-schiefer, argyllite, phyllite) as they contain
more uncrystalline matter, and possess a more definitely
slaty structure. So also bedding planes are more easily
distinguishable in these, if at all; and altogether their
sedimentary or clastic origin is more evident. At the
same time they are metamorphosed in varying degrees,
and possess many secondary cleavage structures. These
slates often have a calcareous tendency in their composi-
tion, as is exemplified by the numerous small calcite seams
that intersect them, and the coatings of calcite on their
cleavage planes.

The term éalc (¢alcose, talcotid) slate or schist, used by
Kmmons and Kerr, and generally by many others, isa
mistaken one. It is true that it is perhaps an excusable
error, for these slates and schists are often so soft and
greasy that the resemblance to talc is very great. How-

ever, chemical analysis and other characteristics would

place the mineral in the class of hydro-muscovite or seri- |
cite, the percentage of magnesia being far too small for
talc. Several analyses of type specimens of this rock
from the Haile gold mine in Lancaster county, S. C., by
Dr. Chas. Baskerville, of the University of North Caro-
lina, show:

SiO, 44.61 61.02
Al,O, 31.57 25.54
FeO S355 4.46
CaO 0.20 0.60
MgO 0.22 0.14
MnO GING Hea ee
Na,O 6.96 2.19
K,O 6.97 1.81
H,O 5.80 4.20

100.04 99.96
The term that I shall therefore use as more appropri-

RM cman MR PO ih Roar ot eat Sie aie lee Aer) Bashan aa) Soe Le

th ~. Set he %
ek ee 2 Sos ar ar nee Pix ek o, | os ah Ney Ci 4 rent ~
a ed, Reais eR Ah te. Be pg Oak) re ae BY ; ae 6 Nya Le 4
+ 7 : be chy e : a
F oh a R rt : 2 fu i rw “a Te piste o , y > py aA ie re ae N ¢ Nn 700 yi
ee . - < f Gat : sad Vs . MEY ‘ SOA at sf
3 : - j ‘ 2 ‘ x Hy wot r ‘ f ' if ae :
63 fi JOURNAL OF THE | eee
‘ N . e : - 4 4 os
r4 ? aX ers gh

ate is sericite schist. The true talc schists are very rare.
_ The chloritic schists are probably more truly crystalline ~
schists, and are richer in accessory metamorphic minerals, i
such as garnet and epidote. a
The argillaceous slates and sericite schists are nae BS
quently silicified; the chlorite schists are not asa rule. : ;
‘This silicification exists in varying degrees up to a com-
pleteness which renders the rock so hard that it resists
scratching with a knife. eo
The strike of the formation as a whole is generally —
northeast, and the dip steepiy to the northwest. ‘These
strikes and dips refer to the schistosity of the rocks, and —
not to the bedding planes. | a
In general the force producing schistosity and slaty
cleavage appears to have acted downward from the north- —
west, producing normal faulting with but little deform-
ation. No instance of reverse faulting was recorded.
Now, as to the origin of these schistose and slaty
rocks; in part it seems that they must be sedimentaries
altered by dynamo- and hydro-metamorphism. The evi- ©
‘dence of this is offered by several observations of bedding
and banding extending across the schistosity, generally
at low angles, although in most instances this original
structure has been obliterated. Kmmons’ supposition
that the gold in the slates and schists is of sedimentary —
origin (page 55) is altogether untenable.
The lamination or schistosity, however, is wholly the
effect of shearing, produced by dynamo-metamorphism.
It has no connection with bedding planes of stratigraphic
structure, as both Emmons and Kerr supposed. The ~
original bedding planes may correspond to certain of the
present cleavage planes, i. e. lie parallel to them, but in
that case the bedding structure has been obliterated.
Schistosity must not be confounded with bedding. a
It does not seem probable, at the present stage of in- ~~
vestigation, that these slates have been derived from the
granitic and other more basic igneous masses lying on —

£ :
‘

ELISHA MITCHELL SCIENTIFIC SOCIETY. — 64

the west; for these are supposed to be later intrusive
bosses. .

That others of these schists, particularly the chloritic
varieties, are metamorphosed, sheared eruptives seems
most probable. They are even porphyritic and brecciated
in places. In fact Emmons hints at such rocks in his
description of his Upper Taconic chloritic member, when
he says: ‘These beds may be mistaken for trap, being
greenish and tough, and besides like trap, the broken
strata become concretionary and exfoliate in concentric
layers.”’ (Page 59.) This subject will be recurred to
later on.

The Monroe States. At Monroe, in Union county, a
considerable area of truly bedded and but little indurated
or metamorphosed slates was discovered. Similar slates.
were also found at the Parker gold mine near New
London, Stanly county, at the town of Albemarle in Stan-
ly county, and at the Sam Christian gold mine in Mont-
gomery county. Thus they presumably cover a large
area in the southeastern portion of the Carolina Slate
Belt. In the fresh condition this slate is black, weather-
ing to dark and light drab, greenish and even reddish
colors. At the railroad station (Monroe) it lies in a low,
gently undulating axticlinorium. Several hundred yards
south. of the depot the strike is N.85°EK., and the dip is
30°S.E. Ata point ; mile north of the depot it is finely
banded and lies nearly horizontal. It has been quarried
here for use as paving blocks in Monroe.

That these slates are of sedimentary origin and of later
age than the slates and schists to the west and north can
scarcely admit of doubt. They are reported to dip under
the Jura-Trias conglomerate at Polkton, about 20 miles
east of Monroe, and might be looked upon as Lower Pal-

- eozoic; but the absence of :fossils (at least so far none

_ have been found, though a careful search is certainly
- warranted) must, for the time being, place them provis- ©

65 JOURNAL OF THE

jonally in the Algonkian, They might appropriately be

named the Monroe slates.

The Volcanic Series. The middle member of Emmons
Lower Taconic is the quartz rock (white and brown sand-
stone), which is stated by him to exist in many varieties;
(p. 57). I did not observe any true granular quartzites,

such as characterize the Cambrian for instance (even in a —
metamorphosed state); and in fact, from Emmons’ ana ~~

Kerr’s descriptions, their rocks of this class are rather
fine-grained, thin bedded, quartzose schists, and devitri-

fied quartz or chert, often porphyrized and brecciated.
It is probable that Emmons’ fine grained talcose quartz |

(p. 58) corresponds to the silicified schists, (p. 63) whose
quartzitic nature is due to a later hydro-silicification.

The crypto-crystalline varieties of quartz (flint, chert,
hornstone) are of especial interest, and warrant a careful
consideration. It is at present the opinion that these
rocks belong to the class of ancient (pre-Cambrian) acid
volcanics, in many respects analogous to, and probably
contemporaneous with, similar rocks of the South Moun-
tain in Maryland and Pennsylvania, whose discovery was
first announced by the late Dr. George H. Williams.1
Miss Florence Bascom has described the origin, devitri-
fication and structure of the acid types of these rocks.”
And Dr. Williams has outlined the general distribution
of the ancient volcanic rocks along the eastern border of
North America.* These rocks are analogous also to the
halleflintas and eurites of Southern Sweden, described as
volcanic rocks by Nordenskjéld. ‘They would also cor-
respond to Hunt’s pre-Cambrian petro-silex rocks, called
by him the Arvonian, being below his Huronian.

The hornstones have every appearance of being acid
feldspar quartz rocks, and will probably be found, on

1The Volcanic Rocks of the South Mountain in Pa.and Md. Am. -

. Jour. Sei. xliv., Dec. 1892. pp. 482—496.
2 Jour. Geology, Vol. 1. 1893. pp. 813—832.
3 Jour. Geology, Vol. 2. 1894, pp. 1—31.

“ eae:
Pere ene wes

Chie :
oS a Mee SE hi

wt

- ‘

*
=

~

ne

Rh ce 2

#
iB

u er rail ‘to! Vee to the class’ of apo- Hye Shih
fen introduced by Miss Bascom to denote a devitrified —
evorte.: Emmons describes the type very well ‘under. Y ce:
the head of quartzite (p. 59). They resemble perfectly. te
_ erypto-ceystalline quartz, and on weathering present an — .
earthy, yellowish surface. Theécolor of the fresh rock is ae

othe Pa
drab, bluish to almost black; translucent on edges; fae ae

“ture flat conchoidal; sometimes banded, showing flow ie
- structure, as at the Silver Valley mine in Davideoas Hi
county, where the rock is locally called ‘“‘gun-flint..? It — ee
a2 often contains small crystals of metallic sulphurets, a

eieny pyrite with some galena, chalcopyrite and blende.

¢ At the Moratock gold mine in Montgomery county, a —
i Sliceous rock occurs in large masses, which at first dahhe ay
"resembles a compact, homogeneous hornstone, but which er
on close investigation is found to be dotted with small, ee
| ~ dark- colored, glassy specks. ‘These are minute quartz es
| ‘crystals, and the microscopic examination of thin sections pee
ee: shows the rock to be an undoubted quartz-porphyry. i

‘Its true porphyritic character is best illustrated in the Yores

ae weathered specimens, the feldspathic groundmass_ be- a
ae ing decomposed and altered, leaving the quartz pheno- Or
Sa crysts clearly outlined. The flow’ structure is also beau- i gare
7 tifully brought out in the weathered groundmass: > ie
~~ Emmons, in his description of his quartzite, states that —) ~
oe it is often porphyritic an] porphyrized, and that fre- | ie
ven quently the fresh fractute is dotted with small limpid | gen
hs . crystals of quartz (p..59). | sy

In the enumeration of the varieties of Lower ‘Vaconic a
Ks quartz rocks (p. 57) he mehtions a cherty or apparently —
~ porphyrized quartz, which contains feldspar, which de= ie
ae composes -and leaves a rough porous mass similar _ to. a
- burrhstone.’’ Kerr says: ‘‘In Montgomery county, in e
cw a very heavy ledge of siliceous slate, occurs a siliceous:
re conglomerate which is filled for hundreds of feet with -
| very singular, siliceous concretious, some of which Dr.
- Emmons has described under the name. of Palestcochiage

/ ‘

hips et ae
ay mm RSs
? Regan tin SFA

iJ a
ANS | aan
j ’ oy ©
1 ane wt dt
ai tyhs f ay, fs - rs §

BA NP Maas TOURNAS OR ati One
bint the rock for several miles, as well as. at this” - ae

particular locality, contains a multitude of rounded and |
ovoid mass:s, from the smallest sizes to that of a hen’s

-egg, showing the wide prevalence of conditions favorable ae
to the operation of concretionary forces’’ (p. 61).- These a i
gentlemen have without much doubt described the quartz -
porphyry of the Moratock mine, or one similar thereto. |

It appears highly probable that at least some of these:
siliceous, so-called pebbly concretions are spherulites. ~
Whether they constitute Emmons’ pebbly beds, from
which he determined the sedimentary origin of his Ta-
conic, is not known. However, it is quite possible that
they misled him in that direction. Certain it is that he
says: ‘‘I found, however, many beds among them (slates
and associated rocks) which looked like sediments, were
porphyrized, and somewhat changed, though not strictly
porphyries. I found after much search too, beds which
were unequivocally pebbly; and finally, to remove all
doubt, I was fortunate in discovering that the porphy-
rized beds also frequently contained pebbles; proving
most conclusively that they are sediments which were
partially altered”’ (p. 55).

Thus he evidently mistook either the concretionary
form of the weathered porphyry and felsite, or else the
partially rounded felsite fragments in the accompanying
pyroclastic breccias (which will be spoken of later on) for
pebbles.

‘Prof. Marsh in 1867 made a short study of Emmons’.
Paleotrochis, andin his words: ‘‘An examination of the

interior of several specimens clearly indicated that they

Were not corals, and as soon as microscopical specimens
could be prepared, they were more carefully examined,
but no trace of organic structure could be detected, the
entire mass being evidently a fine grained quartz. The
Specimens examined were undoubtedly authentic examples

1Am. Jour. Sci. (2), Vol. 45, 1868, p. 217.

ELISHA MITCHELL SCIENTIFIC SOCIETY. \ 68

of Paleotrochis, as some of them presented to the Yale
cabinet by Prof. Dana, were sent to him by Prof. Em-
mons, and the rest were given to the writer by Prof.
W. C. Kerr, the present state geologist of North Caro-
lina. * * * * Admitting the inorganic nature of
these remarkable torms, their origin becomes an interest-
ing question, and it certainly is not easy to give a satis-
factory explanation of it. They appear, however, to have
some analogy with ‘‘cone in cone,’’ which, as the writer
has shown elsewhere,’ is probably due to the action of
pressure on concretionary structure when forming. In
some respects the two are quite distinct, but evidence of
pressure is clearly to be seen inboth.”’

Kerr evidently agreed with Marsh as to the inorganic
nature of the Paleotrochis, and Mr. C. D. Walcott, the
director of the U. S. Geological Survey, entertains the ©
same opinion.”

According to both Emmons’ and Kerr’s descriptions,
these peculiar forms appear to occur in what are now
known to be the acid effusive rocks. In his descriptive
section of the rocks which carry the Paleotrochis, Km-
mons names the following (p. 56):

“Granular quartz, sometimes vitreous and filled with
fossils and siliceous concretions of the size of almonds. *

“Slaty quartzite with very few fossils.

‘Slate without fossils.

“White quartz more or less vitrified filled with fossils
and concretions.

“Jointed granular quartz with only a few fossils.”’

And he says: ‘‘These fossils also occur in the variety
of quartz or quartzite, which I have described as burrk-
stone, and which is often porphyrized.”’ (p. 56.)

An interesting point is suggested in the above succes-
sion of rocks, namely, that there was more than one vol-

1Proc. Amer. Assoc. Adv. Sci., vol. 16, 1867, p, 138,
2Private communication to the writer.

ak t
sha

be

Ache acid volcanies are accompanied by. ope
Paeeacs and basic eruptives. The basic rocks are.
dark green color, and are perhaps pyroxenic in compo:
Be See. They cover large areas, and are often massive i
only partly schistose; again they are largely sheared inte ) ie
- aie It i is pine probable that most. of the oe

"Phe breccias consist of this basic material in whe are. ‘

Be i

bc abbddded angular fragments of the felsite (apo- -rhyolite) f

”

bye. 3,-OF F porphyry edi to one ‘foot in abacaab tes paige: are ica
a oh -

a Pe ky r ite as it may be APRN called, is later than ae:
ia the quartz porphyries and rhyolites. This would agree
vy Ad with the generally. accepted law of eruptions, 1. c, from is
ey: the normal to the acid to the basic types. ie
4 Emmons, in his description of the Upper Taconic, me one

“tions brecciated conglomerates as the most remarkabl
oo mass of this division. As he states, ‘It has an argill:
as ceous or chloritic base. nee mass is ee in he

”

‘

; emi ioabd i in the mass. Nhe fr agments are sometimes 18° ;
Pe inches and even 2 feet: Jone.’’.(p. 39.) ‘yee aay
i Kerr mentions brecciated and conglomerated (siliceous:
‘slates, the pebbles sometimes a foot and upwards in di-
ameter, frequently chloritic and often passing into’ horn-—
stone and chert, arid occasionally into quartzite” [p. 60]). ;
That these rocks correspond to the above described. pyro~
- “clastic breccias'is at once evident. ot
‘ These ancient volcanics have- also been found covering:
ee: large areas iu Chatham and Orange counties, near the 7

ay eastern edge of the Carolina Slate Belt, and fully 40° -
BAe miles east ‘of the region in¢luding the above describe d ie

‘ Me

ELISHA MITCHELL SCIENTIFIC SOCINTY. 70

aes Taistics. During the summer of 1893, Dr. George H.
a Williams in company. with Prof. J. A. Holmes, State
Geologist of North Carolina, made a reconnaissance trip

through Chatham and Orange counties, the results of

~ which are included in Dr. Williams’ paper on the distri-,
» bution of the ancient volcanic rocks in eastern North '

America.’ Hesays: ‘‘In adrive from Sanford to Chapel
Hill an abundance of the most typical ancient lavas, most-
ly of the acid type, was encountered. On the road from
Sanford to Pittsboro purple felsites and porphyries show-
ine spherulitic and beautiful flow structures, and accom-
panied by pyroclastic breccias and tuffs, were met with
two miles north of Deep river, and were almost continuous-
_ ly exposed on Rocky river Hers devitrified acid glasses

ae
t

with chains of spherulitic and eutaxitic structure were
collected, while beyond, as far as Bynum on Haw river,
four miles northeast of Pittsboro, the only rocks seen.
‘were of the same general character. On the farm of:

Spence Taylor, sq., in Pittsboro, a bright red porphyry
with flow lines is exposed in so altered a condition that
hee: oan easily be cut into any form with a knife, though it
still preserves all the details of its structure. * .* *
Three-quarters of a mile beyond Pittsboro, on the Bynum

road, there is a considerable exposure of a basic amygda-~

loid. South of Hackney’s Cross Roads there are other
excellent exposures of ancient rhyolite with finely devel-
»' .oped spherulitic and flow structures. * * * Another
locality in the volcanic belt was visited on Morgan’s run,

about two miles south of Chapel Hill. Here are to be.

seen admirable exposures of volcanic flow and breccias
with finer tuff deposits, which have been extensively

sheared into slates by dynamic agency. ‘Towards the

east and north these rocks pass under the transgression
of Newark sandstone. * * * From still another local-
ity at the Cross Roads near the northern boundary of

1 Jour. Geol., vol. 2, 1894, pp. 1-82,

See

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vee

brecciated and usually sheared into perfect crystalline

71 70% , JOURNAL, OF THE

Chatham county, Btieed miles southwest of Chek Hill, |
Professor Holmes informs me that specimens of undoubt- oY :.
ed volcanic rocks have recently beensecured. He has also Be.
sent me, within the past month, a suite of similar speci-
mens from Pace’s Bridge, on Haw River, three miles 4
above Bynum.”’ a |
Since that time the same Spleaivion have phen found at |
the Narrows of the Yadkin river, along the Deep river at
Lockville, and for five or six miles northwest of Lock-
ville. At the last two localities the masses are often

chloritic schists. ,

It is of interest to note, in the above descriptions of Dr.
Williams, the occurrence, on the Taylor farm near Pitts-
boro, of a bright red porphyry with flow lines, in so alter-
ed a conditfon that it can be easily cut into any form with
a knife. This is undoubtedly the same rock, and from
the same locality, as that described by Emmons asa de- _
composed red variety of his Upper Taconic argillaceous
or clay slate. (p. 58).

Conclusions. In this brief resumé, then, we can recog-
nize Emmons’ Taconic and Kerr’s Huronian rocks of the
central gold-bearing slate belt. yan

The bitter controversies regarding the Taconic ques-
tion among geologists are well known, and need not —
be taken up here. It is sufficient to say that geologists
by later and more detailed work and study have seen fit a
to differentiate various members of the old Taconic sys- —
tem in different parts of the country, and refer them to
more definite horizons. Thus the granular quartz of © |
Emmons’ typical Taconic section in the Berkshire Hills
of Massachusetts, has been found to be characterized by
the Olenellus fauna of the Lower Cambrian; and the
Berkshire or Stockbridge limestone by the Chazy-Tren- _
ton, and perhaps at its base byan Upper Cambrian fauna; ~_
and the original Lower Taconic slate of Emmons is cor- —
related, by its stratagraphic position, with the Hudson

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‘

ELISHA MITCHELL SCIENTIFIC SOCIETX. 72

shales.’ In 1888, Walcott, in studying a section of these

rocks in Newfoundland, placed, from paleontological evi-

dences, the ‘‘Red Sandrock’’ series, the Georgia shale
and slate series, the ‘‘Granular Quartz’’ and ‘‘the Upper
Taconic”? of Enimons beneath the Middle Cambrian or
Parodoxides zone of the Atlantic coast.”

And so the rocks of the old Taconic or Huronian belt
in central North Carolina must also in time be differenti-
ated and recorrelvted when they have been more carefully
_ studied. |

Emmons was in a measure quite correct in calling his
Taconic rocks of central North Carolina the bottom sedi-
-ments, and placing them below the Silurian. The
absence of fossils in the slates, however, necessitates our
going back still another step, and placing them below
the Cambrian sediments, in the Algonkian, which Van
Hise has defined as including all recognizable pre-Cam-
brian clastics and their equivalent crystallines, the base
of the Cambrian being placed at the Olenellus fauna.*
Here the matter must rest until we can find fossils in the
rocks, or verify the organic character of Emmons, Paleo-
trochis; or until we can trace the rocks into a terrane of
known age. Soalso the pyroclastic volcanics must be
looked upon as pre- -Cambrian.

It is of interest to note that here, as in other portions
of eastern North America, the ancient volcanics occur in
close proximity to the western edge of the Jura-Trias
basin. Adopting Suess’ theory of the formation of moun-
tians, we may look upon this central belt of sheared and
faulted slates as the levelled site of an ancient Atlantic
mountain range; while the bodering Jura-Trias represents
a transgression formed by the sunken block on the east;
and the early phases of this subsidence were accompanied
by the exhibition of volcanic forces.

1U. S. Geological Survey. Bull. 81. Correlation Papers: by C. D.
Pe ercott 1891, p. 243.
2 Ibid, p- 113.
3U. S. Geological Survey. Bull. 86. Correlation Papers: Archean-
Algonkian: p. 495.

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