Rodolfo Amedeo Lanciani.

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Andropogon scoparius, 40 per cent Linum Boottii 10 plants.
Andropogon furcatus 1 plant Solidago linifolia 4 plants.



Erifferon canadense 1 plant
Euhnia eupatorioides 1 plant.
Petalostemon violaceum 1 plant
Rosa bland a 8 plants.
Petalostemon candidum 1 plant
Silphium laciniatum 2 plants.
Panicum dichotomum 1 plant
Helianthus rigidus 3 plants.
Euphorbia corollata 1 plant
Sondago rigida 1 plant



Sorghum nutans 80 per cent
Gerardia asperifolia, 60 plants.
Eoeleria cristata, 10 per cent
Helianthus rigidus 26 plants.
Adter multiflorus 1 plant
Solidago Missouriensis 2 plants.
Amorpha canescens 1 plant
Panicum panciflorum 8 plants.



Polygala verticillata 3 plants.
Baptisia leucantha 1 plant
Antenaria dioica 3 plants.
Kuellia ciliosa 1 plant
Coreopsis tinctoria 1 plant
Psorafea floribunda 1 plant
Eryngium yucciefolium 1 plant.



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W.T. Bc^pper on some Minerals from New Jersey. ^ 85

Same area in Linn county ; liigli prairia

Andropogon furcatos 80 per ceDt. Liatris squarrosa 8 plants.

Andropogon scopariaa 5 per cent. Euphorbia corollata 1 plant.

Sorgharn nutans 8 per cent. Panicura dichotomum 8 plants.

Lespedeza capitata 5 plants. Eceleria cristata 1 plant

Solidago Missouriensis 6 plants. Oxalis violacea 1 plant

CeanoSius ovalis 1 plant Echinacea angustifolia 1 plant.

Aster azureus 8 plants. Lin urn Boottii 1 plant

Aster oblon^folius 5 plants. Polytsenia Nuttallii 1 plant.

Solidago linifolia 1 plant. Bouteloua cnrtipendula 1 plant

Salvia Pitcheri 1 plant Ambrosia pycnostachya 1 plant.

Amorpha canescens 5 plants. Petalostemon violaceuno 1 plant

Helianthns rigidns 3 plants. Polygala incamata 1 plant



Art. V. — Notice of some Minerals from New Jersey; by Pro£
W. T. Egbppeb, of Bethlehem, Pa.

1. Iron, Manga)iesej Zinc, Chrysolite,

The Stirling Hill, Sussex county, N. J., which witli its neigh-
bor, the Minehill, seems to be an inexhaustible storehouse of
interesting minerals, both scientifically and commercially, has
furnished an antitype to Prof Brush s Hortonolite from the
adjoining Orange county.

Some years ago I examined a black crystalline massive min-
eral from this locality, and foimd it to be a unisilicate of the
protoxyds of iron, manganese, zinc and magnesium, and as
it showed many of the characteristic physical and chemical
properties of chirysolitic minerals, especially that peculiar mot-
tied coloring, which is so marked in olivmes, I supposed it a
variety of tephroite, that peculiar subspecies of the groiip hav-
ing shortly l^fore been rediscovered by Prof Brush. During
a visit to the locality in the course of last year, I succeeded in
finding distinct crystals, which at once ranged the mineral un-
mistakably among the chrysolites.

OrystaMissaMan, — The crystals occur in great numbers, grouped
together, and of all sizes, m>m an eighth of an inch to two inches
in length and nearly one inch in breadth. They are mostly
rounded, owing to an incipient alteration of the siirface through
meteoric waters, black and duU on the outside, but with lus-
trous and brilliant cleavages on being broken. Some of them,
however, are sharp, and allow of a measurement of angles at
least by the hand-goniometer. The dominant forms are : t2 (an-
gle over it, 130°), vi {ii/\i%, 116°), It (angle at top, 77°^. Gene-
rally subordinate I have observed the following forms : tt, 1-?, I-2,
O, and a fece replacing combination edge i-a Al-* with parallel



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36 W. T. Bospper on some Minerals from New Jersey.

intersection-edges, in whicli therefore n' = —7 - — , to wliich

among simple coeflScienta the forms 2-i or 8-3 would answer.
The ace is too small and dull to allow of a measurement of
angle ; 2-i appears however the more likelj form, as chrysolites
seem to have a preference for the ratio 1 : % Cleavages, three
rectangular ; O and i-% very and almost equally eminent, with
vitreo-pearly luster approaching the sub-aoMnantme ; i-l splin-
tery. Ua/rmess=b-b-^, &>. 'G^.=8'95-4*08. The average of nine
determinations with Jolly^s spring balance gave 4*023. Cb&w,
dark green to black but eminently mottled, so that thin splinters
or laminae transmit a pale yellow liffht Streak, light-yellow-
ish-reddish-gray. The powder is slightly attracted by the mag-
net BB. rather refractory, fusing at thin edges to a dull black
sla^. On charcoal ^ves a zinc coating, more distinctbr on ad-
dition of soda. With the fluxes the usual reactions K)r silica,
iron and manpmese. The borax and microcosmic beads give
in the O. P. the characteristic brownish purple color, indicating
mixtures of iron and manganese, which becomes green in the
reducing flame. With acids gelatinizes readily and completely.
Some specimens leave a bright green undissolved residue, which
I judge to be spinel both fixMn its hardness, its not being at-
tacked by ftision with soda, and complete decomposition by
bisulphate of soda.

In the following analyses the silica was separated in Ae usual
manner, the filtrate from tiie silica neutralized by carbonate of
soda, then acidified with acetic add and a current of sulphuret-
ted hydrogen passed through the solution, which separated the
zinc as sulphid. This was filtered off, redissolved in HCl,
and then precipitated from the uninterruptedly boiling solution
by slowly adding SfaO, and the 2tiO finally converted into 7^
by ignition. The filtrate after the separation of the zinc was
then boiled with the addition of IKOjOlOs to sesquioxydize the
iron, the iron precipitated in the usual manner as subacetate, re-
dissolved and reprecipitated by ammonia, the manganese separa-
ted by bromine and determined as pyrophosphate with the pre-
cautions pointed out by Dr. Gibbs, (this Journal, No. xxxi, p.
21S), and lasfly the m^nesia determined as pyroi)hosphate. I
will here remark, that i did not succeed in separating the oxyd
of zinc from the iron by the usucJ acetate of soda process, but
that a great and often the greater part of the & went down
with the iron, which I attribute to the necessary boiling of a
dilute solution (vid. Johnson's QuaL Pres^us). Hence my
former analyses were not correct, gave too littie zinc and resulted
in uni-oxygen ratio only on account of the near proximity of
the equivdents of iron, manganese and zinc-oxyds. I may,
however, not have handled the method correctiy.



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W. T. Bc^pper (m 9(mte MhherciU from N^ 87

The samples No. 1 and 2 were fresh pieces of cleavage crystals
carefiiUy examined by the lens so as to avoid all visible admix-
tnres. No. 1 was lighter in color than No. 2, a and 6, which
latter are analyses of the same powder. No. 8 are analyses of
two different powders of the massive variety.





1.


a

a


h


a

a





1.


2,0.


Dxy^a


3,0.


i
3,6.


Si...


30-76

3378

16-26

10-96

7-60


29-90

36-60

16-90

10-66

6-81

103


30-66

36-44

16-93

10-70

6-44

1-04


30'67

36-37

17-81
9-87
6-69
1-39


30-42

34-20

17-67

9-09

6-49

2-66


16-41


16-96


16-30


16-36


16-22


ftn..
Insol.


•7-61
3-66
216
804


7-91
3'81

2-n

2-32


7-88
3-82
2-11
218


7-86
4 01
1-96
2-28


7-60
3-98
1-80
2-60




99-35


99-90


10011


100-80


100-62


16-37


16-16


16-99


1610


16-98



The foregoing oxygen ratios make the mineral a unisilioata
The crystfdlization being orthorhombic with the parametric
ratios of the chrysolite group, which is confirmed by the other
physical and chemical characters ; it is hence an iron-manganese-
zinc chrysolite, the first, to the best of my knowledge, of the
group, into the composition of which zinc enters as a constituent

It occurs, as before said, on Stirling lull, accompanied by
Willemite, Franklinite, Jeffersonite and spinel

2. Mcmgcmesian Dolomite.

In the vast vein of Willemite, which is being worked on
MinehOl by the New Jersey Zinc Company, there occur small
masses of a beautiful delicate pink mineral with a rhombohedral
cleavage, which by their contrast with the purely apple-green
Willemite make exceedingly pretty specimens. An analysis
gave the following composition :

()&Q ULuO feQ iLgG InsoL

5040 43-54 '76 569 0*08 = 10047

Specific gravity =8*052. Hardness =4.

The mineral differs firom the known dialogites hj its greater
proportion of carbonate of lime, and may be considered either
as a dialogite in which a little more than one-half of the Stn is
replaced by lime, or as a dolomite in which about five-sixths of
the magnesia is replaced by ftn.

8. A pseudomorph of opal after a micojceous mineral probably

some chlorite.

On Scotch mountain, Warren county, N. J., not far firom New
Village, among the Laurentian syenitic gneiss formation of that
region, there occur, scattered over the ground, numerous masses
of a white a uartzose mineral apparently of agglutinated rounded
granules oi about J inch diameter. Upon close examination,



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88 W. Thompson on the size of Atoms.

many of these granules show distinct cleavages, which exhibit
a hexaffonal outline. Searching the ground carefully I found
wonnl&e contorted crystals, in shape like the similar forms of
some chloritic minerals. The substance is distinguished from
quartz by its low specific gravity =1'961, and inferior hardness
(nea» 6). It is mostly soluble m caustic potash, leaving only 8
per cent insoluble, wnich seemed to consist, in part at least, of
the original mineral. On ignition it loses 7*27 per cent water.
It is therefore manifestly amorphous quartz or opaL Indeed
smaU masses of unquestionable opal of various colors are found
in the neighborhood.

It hence appears, that micaceous structure is not, as is fre-
quently assumed, the absolute closing scene of the metamor-
phism of minerals, but that the replacing power of sQica is able
to overcome the antimetamorphic energies of minerals even,
which have arrived at the micaceous stage.

Beihlehem, April 22, 1870.



Art. VL — On the Size of Airnns; by Prof Sir W. Thomson,

F.RS.*

The idea of an atom has been so constantly associated with
incredible assumptions of infinite stren^di, absolute rigidity,
mystical actions at a distance, and indivisibility, that chemists
and many other reasonable naturalists of modem times, losing
all patience with it, have dismissed it to the realms of metaphys-
ics, and made it smaller than "anything we can conceiva"
But if atoms are inconceivably small, why are not all chemical
actions infinitely swift? Chemistry is powerless to deal with
this question, and many others of paramount importance, if
barred by the hardness of its fundamental assumptions, fix>m
contemplating the atom as a real portion of matter occupying
a finite space, and forming a not immeasurably small constitu-
ent of anv palpable body.

More than tnirty years ago naturalists were scared by a wild
proposition of Gauchy's, that the familiar prismatic colors
proved the "sphere of sensible molecular action" in trans-
parent liquids and solids to be comparable with the wave-
length of light The thirty years which have intervened have
only confirmed that proposition. They have produced a large
number of capable judges ; and it is only incapacity^ to judge
in dynamical questions that can admit a doubt of the substan-
tial correctness of Gauchy's conclusion. But the " sphere of
molecular action " conveys no very clear idea to the non-mathe-

♦ Prom Nature, No. 22, March 31.



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W. Thompson on the size of Atoms. 89

matical mind. The idea which it conveys to the mathematical
mind is, in my opinion, irredeemably felse. For I have no
faith whatever in attractions and repulsions acting at a distance
between centers of force according to various laws. What
Cauchy*s mathematics really proves is this : that in palpably
homogeneous bodies, such as glass or water, contiguous portions
are not similar when their dimensions are moderately small
fractions of the wave-lencth. Thus in water, contiguous cubes,
each of one one-thousandth of a centimeter breadth, are sen-
sibly similar. But contiguous cubes of one ten-millionth of a
centimeter must be very sensibly diflferent So in a solid mass
of brickwork, two a(^'acent lengths of 20,000 centimeters
each, may contain, one of them nine hundred and ninety-nine
bricks and two half bricks, and the other one thousand bricks :
thus two contiguous cubes of 20,000 centimeters breadth may
be considered as sensibly similar. But two adjacent lengths of
forty centimeters each might contain, one of them one brick
and two half bricks, and the other two whole bricks ; and con-
tiguous cubes of forty centimeters would be very sensibly dis-
similar. In short, optical dynamics leaves no alternative but
to admit that the diameter of a molecule, or the distance
from the center of a molecule to the center of a contiguous
molecule in glass, water, or any other of our transparent liquids
and solids, exceeds a tcD-thousandth of the wave-length, or a
two-hundred-millionth of a centimeter.

By experiments on the contact electricity of metals made
eight or ten years ago, and described in a letter to Dr. Joule,
which was published in the Proceeding of the Literary and
Philosophical Society of Manchester, I found that plates of
zinc and copper connected with one another by a fine wire
attract one another, as would similar pieces of one metal con
nected with the two plates of a galvamc element, having about
three-quarters of the electro-motive force of a Daniel's element

Measurements published in the Proceedings of the Eoyal
Society for 1860 showed that the attraction between paraUel
plates of one metal held at a distance apart small in com-
parison with their diameters, and kept connected with such
a galvanic element, would experience an attraction amount-
ing to two ten - thousand - miUionths of a gram weight per
area of the opposed surfaces equal to the square of the
distance between them. Let a plate of zinc and a plate of
copper, each a centimeter square and a hundred-thousandth of
a centimeter thick, be placed with a comer of each touching a
metal globe of a hundred-thousandth of a centimeter diameter.
Let the plates, kept thus in metallic communication with one
another be at first wide apart^ except at the comers touching
the little globe, and let them then be gradually tumed r6und



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40 W. Tfurnipeon on the size of Atoms.

till they are parallel and at a distance of a linndred-thotisandth
of a centimeter asunder. In this position they will attract one
another with a force equal in all to two grams weight By ab-
stract dynamics and tne theory of energy, it is r^dily proved
that the work done by the changing force of attraction during
the motion by which we have supposed this position to be
reached, is equal to that of a constant force of two graiiis
weight acting through a space of a hundred-thousandth of a
centimeter; that is to say, to two hundred-thousandths of
a centimeter-gram. Now let a second plate of zinc be brought
by a similar process to the other side of the plate of copper ;
a second plate of copper to the remote side of this second plate
of zinc, and so on till a pile is forme4 consisting of 50,001 plates
of zinc and 50,000 plates of copper, separated by 100,000
spaces, each plate and each space one hundred-thousandth of
a centimeter thick. The whole work done by electric attrac-
tion in the formation of this pile is two centimeter-grams.

The whole mass of metal is eight grams. Hence the amount
of work is a quarter of a centimeter-gram per gram of metal
Now 4,030 centimeter-grams of work, accord-mg to Joule's
dynamical equivalent of heat, is the amount required to
warm a gram of zinc or copper hj one d^ree centigrade.
Hence the work done by the electric attraction could warm
the substance by only ttttit of a degree. But now let the
thickness of each piece of metal and of each intervening space
be a hundred-millionth of a centimeter instead of a hundred-
thousandtL The work would be increased a million-fold un-
less a hundred-milliontii of a centimeter approaches the small-
ness of a molecule. The heat equivalent would therefore be
enough to raise the temperature of material by 62°. This
is barely, if at all, admissible, according to our present knowl-
edge, or, rather, want of knowledge, regarding the heat
of combination of zinc and copper. But suppose the metal
plates and intervening spaces to be made yet four times
thinner, that is to say, the thickness of each to be four-
hundred-millionth of a centimeter. The work and its heat
equivalent will be increased sixteen-fold. It would there-
fore be 990 times as much as that required to warm the mass
by 10 cent, which is very much more than can possibly be
produced by zinc and copper in entering into molecular com-
bination. Were there in reality anything like so much heat
of combination as this, a mixture of zinc and copper powders
would, if melted in any one spot, run together, generating more
than heat enough to melt each throughout; just as a lai;^
quantity of gunpowder if ignited in any one spot bums through-
out without fresh application of heat Hence plates of zinc
and copper of a three-hundred-millionth of a centimeter thick,
placed close together alternately, form a near approximation to



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W. Thompson on the swe of Atoms. 41

a chemical combination, if indeed such thin plates could be
made without splitting atoms.

The theory of capillary attraction shows that when a bubble
— a soap-bubble for instance — is blown larger and lar^r, work is
done by the stretching of a film which resists extension as if it
were an elastic membrane with a constant contractile force.
This contractile force is to be reckoned as a certain number of
units of force per imit of breadtL Observations of the ascent
of water in capillary tubes shows that the contractile force of a
thin film of water is about sixteen milligrams weight per
millimeter of breadtL Hence the work done in stretching a
water film to any degree of thinness, reckoned in miUimeteav
milligrams, is equal to sixteen times the number of square
millimeters by which the area is augmented, provided the film
is not made so thin that there is any sensible diminution of its
contractile force. In an article "On the Thermal effect of
drawing out a Fihn of Liquid," published in the Proceedincs
of the Iloyal Society for April, 1858, 1 have proved from the
second law of thermodynamics that about half as much more
energy, in the shape of heat, must be given to the film to pre-
vent it fix)m sinking in temperature while it is being drawn out
Henoe the intrinsic energy of a mass of water in the shape of
a film k^t at constant temperature increases by twenty-four
milligram-millimeters for every square millimeter added to its
area.

Suppose then a film to be given with a thickness of a milli-
meter, and suppose its area to be augmented ten thousand and
one fold: the work done per sq^uare millimeter of the orig-
inal film, that is to say per miUigram of the mass, would be
240,000 millimeter-milhgrams. The heat equivalent of this
is more than half a d^ree centigrade of elevation of tempera-
ture of the substance. The tmckness to which* the film is
reduced on this supposition is very approximately a ten-thou-
sandth of a millimeter. The commonest observation on the
soap-bubble (which in contractile force differs no doubt very
little from pure water) shows that there is no sensible diminu-
tion of contractile force by reduction of the thickness to the
ten-thousandth of a millimeter; inasmuch as the thickness
which gives the first maximum brightness round the black
spot seen where the bubble is thinnest, is only about an eight-
tnousandth of a millimeter. •

The very moderate amount of worif shown in the preceding
estimates is quite consistent with this deduction. But suppose
now the film to be further stretched, until its thickness is
reduced to a twenty-millionth of a millimeter. The work
spent in doing this is two thousand times more than that which
we have just calculated. The heat equivalent is 1,180 times



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42 W. Thompson on ike sisse of Atoms.

the quantity required to raise the temperature of the liquid
by one degree centigrada This is far more than we can aomit
as a possible amount of work done in the extension of a liquid
film- A smaller amount of work spent on the liquid would
convert it into vapor at ordinary atmospheric pressure. The con-
clusion is unavoidable, that a water-film falls off greatly in its
contractile force before it is reduced to a thickness of a twenty-
millionth of a millimeter. It is scarcely possible, upon any
conceivable molecular theory, that there can be any considera-
ble falling off in the contractile force as long as there are
several molecules in the thicknes& It is therefore probable
that there are not several molecules in a thickness of a twenty-
millionth of a millimeter of water.

The kinetic theorjr of gases suggested a hunded years ago
by Daniel BemouiUi has, during me last quarter of a century,
been worked out by Herapath, Joule, Clausius, and Maxwell,
to so ^eat perfection that we now find in it satisfactory ex-
planations of all non-chemical properties of gases. However
diflScult it may be even to imagine what kind of thing the
molecule is, we may regard it as an established truth of science
that a gas consists of moving molecules disturbed fix>m recti-
lineal paths and cxjnstant velocities bv collisions or mutual
influences, so rare that the mean length of proximately recti-
lineal portions of the path of each molecule is many times
greater than the average distance fix)m the center of eacn mole-
cule to the center of the molecule nearest it at anv time. K,
for a moment, we suppose the molecules to be hard elastic
globes all of one size, influencing one another only through
actual contact, we have for each molecule simply a zigzag path
composed of rectilineal portions, with abrupt changes of direc-
tioiL On this supposition Clausius proves, by a simple appli-
cation of the calculus of probabilities, that the average length
of the free path of a particle from collision to collision Ijears to
the diameter of each globe, the ratio of the whole space in
which the globes move, to eight times the sum of the volumes
of the globes. It follows that the number of the globes in
unit volume is equal to the square of this ratio divid^ by the
volume of a sphere whose radius is equal to that average
length of free patL But we cannot believe that the individiml
molecules of gases in general, or even of any one gas, are hard
elastic globes. Any two of the mpving particles or molecules
must act upon one another somehow, so that when they pass
very near one another they shall produce considerable deflexion
of the path and change in the velocity of eacL This mutual
action (called force) is different at different distances, and must
vary, according to variations of the distance, so as to fulfil some
definite law. if the particles were hard elastic globes acting



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W, Thompson on the size of Atoms. 48

upon one another only bj contact, the law of force would be
— zero force when the distance from center to center exceeds
the sum of the radii, and infinite repulsion for any distance
less than the sum of the radii This hypothesis, with its
"hard and fast" demarcation between no force and infinite
force, seems to require mitigation. Without entering on the
theory of vortex atoms at present, I may at least say that soft
elastic solids, not necessarily globular, are more promising than
infinitely hard elastic globes. And, happily, we are not left
merely to our fancy as to what we are to accept for probable
in respect to the law of forca If the particles were hard
elastic globes, the average time from collision to collision would
be inversely as the average velocity of the particles. But Max-
well's experiments on the variation of the viscosities of gases
with change of temperature prove that the mean time from
collision to collision is independent of the velocity, if we give
the name collision to those mutual actions only which produce
something more than a certain specified degree of deflection of
the line of motioiL This law could be fulfilled by soft elastic
particles (globular or not globular) ; but, as we have seen, not
Dy hard elastic globes. Such details, however, are beyond the
scope of our present argument What we want now is rough
approximations to absolute values, whether of time or space or



Online LibraryRodolfo Amedeo LancianiThe American journal of science and arts → online text (page 57 of 109)