to study him as he really is we must not isolate him from society. The
evident truth of this may lead us to forget that it is but a half truth
and the uncritical acceptance of it will lead us wholly astray in our
sociological study. The inference which we seem compelled to draw from
studies in social psychology is that social man is, in his ethical
and intellectual development, many stages behind the individual man.
The progress of civilization is a slow, painful, upward climbing, in
which individuals are the thinkers, the planners, the promoters and
the leaders. The mind of society, on the other hand, using the phrase
in the sense defined, is an imitative, unreflective, half-hypnotic,
half-barbaric mind, always acting as a drag upon the upward and forward
movement, and, in times of crazes, epidemics and social cataclysms,
gaining temporary dominance and causing disastrous relapses to a lower
plane of civilization.
SOME PHASES OF THE EARTH’S DEVELOPMENT IN THE LIGHT OF RECENT CHEMICAL
RESEARCH.
BY PROFESSOR EDWARD RENOUF.
JOHNS HOPKINS UNIVERSITY.
In the following pages an effort is made to apply some of the results
of recent chemical research to the earlier history of the earth. It is
hoped that the main facts brought out may be readily grasped by those
who have never studied chemistry, and that each link in the chain of
events will be made evident to those who have mastered the rudiments of
this science.
Chemical action involves change of composition. Substances more or
less complex may be broken down into simpler substances, or from
several simpler substances a complex substance may be built up. From
the complex ore of copper found in nature the simple element copper is
obtained. From the elements sulphur and oxygen and the simple substance
water the complex sulphuric acid is built up. Within the last few
years the high temperature of the electric arc--the heat generated
by a powerful electric current playing between two carbon poles--has
been employed in bringing about chemical changes which do not occur
at ordinary temperatures nor at those obtainable by burning fuel. The
electric furnace is used industrially to make calcium carbide from lime
and coke, carbon silicide (carborundum) from coke and sand, and the
metal aluminum from its compounds.
Chemical changes at high temperatures have long been an object of
research, but it was not until the introduction of the electric furnace
that it was possible to command temperatures high enough to make
exhaustive studies. In the last few years several chemists, especially
Moissan, of Paris, and his pupils, have done systematic work with the
aid of the arc furnace. The furnace used in the laboratory for high
temperature work is a small and simple apparatus; Moissan’s furnace is
a block of quick lime a little longer and wider than a page of this
magazine and about three inches thick. A rectangular cavity is cut
on the upper surface of this block. A similar block forms the cover.
In opposite grooves between the top and bottom piece are placed the
carbons, such as are used in ordinary arc lights. The arc plays across
the cavity in such a manner that the substance to be heated is not
brought into the arc itself, which is vaporized carbon, but below it.
The cavity thus represents a tiny reverberatory furnace; the arc heats
the roof and sides to an intense heat, which is radiated on the open
dish or closed crucible or tube containing the substance heated. This
is the simplest form of laboratory furnace. Various modifications
are used, but in all the size is small and the arrangement simple. A
powerful arc plays in the smallest possible cavity with the object
of attaining the maximum of temperature, expense and duration of
material being secondary considerations. Lime and magnesia are the
best materials, because they are at the same time the most refractory
substances available and are poor conductors of heat. A furnace top
one and one half inches thick may be heated by so powerful an arc that
the melted quick lime drips from the inner surface, while the outer
surface is scarcely warm to the touch of the hand. Moissan has utilized
in these little furnaces currents of electricity of varied strength,
the lowest being that given by a four horse-power dynamo, the highest
that generated by three hundred horse power. The highest temperatures
obtained were about 3,500° centigrade (6,300° Fahrenheit), with the
heat constantly increasing; the limit to the obtainable temperature--as
far as the experimental evidence showed--was merely the lack of
any known substance refractory enough to bear the heat; for at the
temperature mentioned quick lime and magnesia not only melt but are
changed into gases, so that the furnace was filled with the vapors of
its own material.
The effect of the heat on single substances is very interesting.
Refractory metals, such as iron, manganese, uranium, platinum, melt
rapidly and then become gaseous; the most refractory non-metallic
elements, silicon, boron, carbon, are also changed into the gaseous
form. Very refractory compounds are broken down into simpler ones.
Magnesium pyrophosphate yields phosphorus, magnesium oxide and oxygen.
Asbestos--a magnesium silicate--gives as chief product magnesium
silicide; the other substances formed being silicon, silicon dioxide
and a little magnesium oxide.
Such are the astounding changes wrought by simple heat upon those
substances which we are accustomed to regard as infusible. It must
be remembered that the range of temperature which chemists employ in
ordinary laboratory work is not very great and that the conditions of
work in the laboratory and of nature’s work on the earth’s surface at
the present day favor the formation of two classes of compounds--the
oxides and their hydrates. Although air is a mixture consisting mainly
of four parts of nitrogen and one of oxygen, atmospheric nitrogen is
generally inert at ordinary temperatures, and it is the oxygen of the
air which is the more important factor in the growth of living things
and in changes in lifeless matter. Water, a compound of oxygen and
hydrogen, is present everywhere, either in the liquid form or as vapor
in the air; even in the flame of the hottest fires there is water vapor
in abundance, since water is one of the chief products of combustion
of most forms of fuel. Is it a wonder that under such conditions we
find the earth’s crust to contain the elements chiefly compounded
with oxygen? Was this always so? Are we justified in supposing that
conditions may have prevailed--nay, must have prevailed--in former
times on the earth’s surface, which gave to other elements as important
or more important functions than to oxygen? The answer to these
questions must be sought in the results of the chemistry of high
temperatures.
First let us consider the conditions of existence of the omnipresent
water. Water begins to break down into its components, hydrogen and
oxygen, at 934° centigrade; at 2,500° centigrade (4,500° Fahrenheit)
the decomposition is complete. In other words, water vapor cannot exist
at temperatures above 2,500°, but the hydrogen and oxygen exist in the
free state.
Astronomers tell us that refractory elements like iron, silicon and
carbon, perhaps disassociated into still simpler substances, are
present as vapor in the atmosphere of the sun and that many others of
our well-known elements, including hydrogen, are also present in this
glowing atmosphere, while the heat of the sun’s surface and that of
the hotter stars is vastly higher than that of the electric furnace.
Geologists believe that the evidence at their disposal points to a
similar period of great heat in the early history of the earth. It
may be considered, then, that temperatures higher than those of the
electric furnace prevailed in former times on the earth’s surface.
Let us now return to the study of the results obtained with the
electric furnace. The following reactions are especially important. If
metals, or refractory non-metals, or metallic or non-metallic oxides,
or complex silicates, are heated to the higher temperatures in contact
with carbon, boron, silicon or compounds of these three elements with
oxygen, the result generally is that very refractory carbides, borides
or silicides of the metals or non-metals are formed. In other words,
those complex substances which form the chief constituents of the
outer crust of the earth at the present day are decomposed at high
temperatures, and simple compounds of two elements--so-called binary
compounds--are formed. Four classes of these binary substances seem to
be especially stable at high heat--the carbides, borides, silicides and
oxides; but the oxygen of the metallic oxides tends to pass off as an
oxide of carbon, if carbon be present.
At somewhat lower temperatures nitrogen is very active and the nitrides
of many metals are readily formed. An excellent example is shown by
heating a mixture of carbon and of an oxide of titanium (titanic acid).
When heated by a feeble current the acid is simply reduced, forming
a lower oxide of titanium; with a more powerful current the mass is
completely changed into the nitride of titanium, the nitrogen coming
from the air; with a very powerful current this is changed into pure
carbide, as the nitride cannot exist at the higher temperature, and the
nitrogen escapes, carbon taking its place. At still higher temperatures
hydrogen acts on many metals, forming hydrides. The carbides and other
compounds of some metals are not stable at high temperatures, being
reduced by gaseous carbon to the free metals, which remain then in the
gaseous form.
At that period of the earth’s history when the temperature was as high
as that easily obtained in the electric furnace, we have the sanction
of geologists for picturing the earth’s surface as an ocean of molten
matter surrounded by a glowing atmosphere. This molten surface must
have consisted of binary compounds such as those mentioned above, and
probably contained some refractory elements, metals and non-metals,
in the free state. The atmosphere contained free hydrogen, oxygen
and nitrogen, gaseous binary compounds like the oxides of carbon,
metals in the gaseous form and many non-metallic elements like sulphur
and chlorine. In the atmospheric region furthest removed from the
molten surface violent chemical reactions occurred between the heated
elements, forming compounds which were again dissipated into their
elements by the heat given off in the act of formation or radiated from
the glowing surface below.
Under the enormous pressure of this atmosphere the liquid surface of
the earth solidified at very high temperature. Whether the earth’s
mass solidified from the centre outward or by forming a solid crust
over a liquid interior, is a question to be decided by physicists and
geologists. We will consider only the outer crust and the atmosphere.
As the surface and the atmosphere above it gradually cooled, the
formation of nitrides, and later of hydrides, sulphides and chlorides,
occurred.
The conditions now attained may have been fairly stable as long as
the temperature of the surface and lower regions of the atmosphere
were high enough to prevent the union of the atmospheric oxygen and
hydrogen, or to decompose the water forming in the outer regions of
the atmosphere. As soon, however, as by further cooling, water came
into contact with the earth’s surface, very violent reactions occurred,
which were supplemented by other equally violent reactions when the
cooling process permitted the formation of the ordinary mineral acids.
The reactions of water and of acids on many of the binary compounds
are so important in determining the present composition of the
earth’s crust that they must be considered in detail. The carbides,
nitrides, chlorides, sulphides and hydrides of most elements, and some
silicides, are decomposed by water, or else by dilute acids, forming
the hydrogen compounds of carbon, nitrogen, chlorine, sulphur and
silicon respectively, and the oxide or hydroxide of the other element.
Thus calcium carbide and water give calcium hydroxide and acetylene,
a hydro-carbon. Aluminum carbide yields alumina and methane (marsh
gas), another hydro-carbon, the chief constituent of ‘natural gas.’
Other carbides yield crude petroleum. The nitrides yield ammonia, which
is the hydrogen composed of nitrogen. The chlorides give hydrochloric
acid, the sulphides sulphuretted hydrogen and the silicides the
hydrogen silicide. The metallic hydrides yield free hydrogen.
The violence and the magnitude of some of these reactions almost baffle
the imagination. Let the reader drop a piece of calcium carbide as
large as a small marble into a little water in a cup; there is a rapid
action, a gas (acetylene) is given off, which burns with a smoky flame
if a lighted match is held over the cup. (The experiment should be
tried in the open air.) So much heat is generated in the reaction that
the cup becomes hot. Nearly four per cent. of the earth’s outer crust
is calcium; all this was at this period of the earth’s history in the
form of carbide. Imagine all the vast limestone mountain ranges of
the present day as carbide, and try to realize the effect when water
fell on any considerable area. The heat generated would be so enormous
that in a moment the acetylene would ignite and burn, forming oxides
of carbon and water vapor, which would in turn decompose, throwing the
jets of glowing hydrogen and oxygen vast distances into the atmosphere,
there to cool and reunite to water. The decomposition of other
carbides, of the hydrides and silicides, as well as the formation of
hydroxides by the action of the lighter metals on water, would produce
similar phenomena, as the substances formed are combustible gases, or
liquids or solids easily volatilized. This is no wild fantasy, but
a conservative statement. Similar reactions are taking place at the
present day in those stars whose cooling process has advanced far
enough; a case in point is that of the so-called ‘temporary stars.’
Extremely violent reactions are taking place constantly in the
atmosphere of the sun. The sun’s chromosphere, or outer layer of its
atmosphere, consists mainly of hydrogen, and jets of glowing hydrogen
are thrown to great heights above the chromosphere; these jets or
‘prominences’ have been frequently observed to have a height of 100,000
miles, and prominences of more than double this height are reported
by observers. The most conservative estimates assume temperatures of
the sun’s surface so enormous that that of the electric furnace is
insignificant in comparison, and we can have no conception of the
chemical changes occurring under such conditions. Whether one believes,
with Lockyer, that the chemical ‘elements’ are disassociated by the
sun’s heat into simpler substances or not, it is clear that very
violent chemical reactions are in progress, and if we realize that
the known chemical reactions increase in intensity with increase in
temperature, it does not seem strange that at the sun’s temperature the
reactions occurring should cause disturbances like those observed.
Returning to the earth, let us consider the products of these violent
reactions. The hydrogen and hydrides of boron, silicon, sulphur and
carbon, combined with the oxygen of the atmosphere, forming water and
boric, silicic, sulphurous and carbonic acids, which in turn acted on
the metallic oxides and hydroxides, forming sulphites, carbonates,
borates and simple and complex silicates; some quickly, some slowly,
some at low temperatures and atmospheric pressure, others at high
temperatures in liquid or semi-liquid condition and under the pressure
of rock masses above. To determine the relative age of existing rock
layers, or the mode of their formation, whether by eruptive action, by
surface heat, by deposition of finely divided material under water,
or by metamorphic changes of the cooled silicate under subsequent
action of water, pressure and heat, is the province of the geologist.
The present writer refrains from an opinion whether any of the first
formed solid crust could or could not survive to the present day in
its primary form, considering the exposure to water, acids, heat and
pressure which it suffered.
Yet an idea may be formed of the condition of the earth’s surface when
it had cooled so far that the more violent chemical action had ceased.
It consisted chiefly of silicates, simple and complex; of some of
the original binary compounds, which are scarce affected by water or
acids, such as the silicide of carbon (carborundum), of stable oxides,
chlorides and sulphides, with other compounds in smaller proportion,
and free elements in greater proportion than at the present day.
Everywhere, from crevices in the surface, hydrocarbons, phosphoretted
hydrogen (phosphine) and ammonia were issuing as gases; the atmosphere
was heavy with these gases and with carbon dioxide.
No scientific observations thus far show _how_ or from what definite
compounds plant life or animal life was first evolved from lifeless
matter; but it is certain that the materials were much more abundant
and the conditions more favorable at the period when it _was_ evolved
than at the present day. An ocean much warmer and less saline than now,
a damp atmosphere like that of a hothouse, an abundance of plant food
and a choice of raw material, were at hand. The chief foods required
for plant life are nitrogen in the form of ammonia or nitrates, carbon
dioxide, phosphorus as phosphates, sulphates of lime, of magnesia
and of the alkalies, and water. As to the raw material for the first
formation of the living cell, it is impossible to say what compounds
of carbon were employed; suffice it to note that the known simple
and complex binary compounds of carbon were there ready for use; the
hydrocarbons, carbon monoxide and carbon dioxide were oozing from the
earth’s surface, from the ocean floor as well as from the land, or
hanging heavy in the air above it. If warmth or increased pressure
were desiderata, an ocean warm to its greatest depths could afford
any pressure required. From the decomposition of the nitrides and
phosphides below the surface, ammonia and phosphine were escaping into
the ocean and into the air. The conditions then during long periods
of time were especially favorable for marine life, and as sand and
mud accumulated on the rocky surface of the earth, for land plants;
the absence of a thick soil being more than compensated for by the
abundance of plant food, notably of carbon dioxide and ammonia.
The statement may be found in excellent modern text-books of chemistry
that ammonia is always formed by the decomposition of plants and
animals, accompanied by the further statement that ammonia is a
requisite for plant food. No plants--no ammonia; no ammonia--no plants.
If this were true, the beginning of plant life would indeed have been
a struggle for existence; that it is not true is shown above. This
decomposition of nitrides has ceased practically on the actual surface
of the earth at the present day because the nitrides have all been
decomposed; yet it may be mentioned that specimens of rock freshly
quarried in Sweden were recently found to give off ammonia when wet
with water, showing the presence of nitrides. Below the actual earth’s
surface it is probable that nitrides still exist in large quantity,
for ammonia is one of the constituents of volcanic gases; to believe
that volcanic ammonia is a product of plant or animal decomposition is
difficult; to suppose it formed by the action of steam on nitrides in
the earth’s interior is simple.
Much the same may be said of the presence of carbides. While they no
longer exist on the surface, there is no doubt of their existence
in the interior of the earth, and the volcanic gases contain their
decomposition products. In this connection the theory--first put
forward by Mendelèeff and since supported by Moissan--of the origin
of petroleum, may be mentioned. These writers favor the hypothesis
that it was formed by the decomposition of carbides by water under
pressure; and while the evidence at hand perhaps favors the belief
that the petroleum of the more important oil fields owes its origin to
decomposition of the lower forms of marine animal life, yet there can
be no doubt that petroleum may be formed by carbide decomposition, and
it seems probable that natural gas is in part at least a result of the
same action.
A PRELIMINARY ACCOUNT OF THE SOLAR ECLIPSE OF MAY 28, 1900, AS OBSERVED
BY THE SMITHSONIAN EXPEDITION.
BY DR. S. P. LANGLEY,
SMITHSONIAN INSTITUTION.
Partly in deference to the report of the United States Weather Bureau,
from which it appeared that the chance of a fair eastern sky on the
morning of the eclipse was about 8 to 1, and after examination by Mr.
Abbot of many stations in North Carolina, Wadesboro, of that State, was
selected early in April as the site of the Smithsonian observations.
The advantages of Wadesboro being also recognized by Professor Young,
of Princeton, Professor Hale, of Yerkes Observatory, and the Rev. J.
M. Bacon, of the British Astronomical Association, it came about that
four large observing parties, besides several smaller ones and numerous
excursionists from the surrounding country, were all joined to produce
at Wadesboro one of the largest company of eclipse observers ever
assembled for scientific purposes. It is a matter for congratulation
that the sky at Wadesboro upon the day of the eclipse was cloudless
and clearer than the average, so that the efforts of the observing
forces were not thwarted by any circumstances beyond their control. The
provisions of the Mayor and authorities of Wadesboro for preventing
intrusion before and during the eclipse, and thus securing an
undisturbed field of operations, deserve especial recognition. Further
than this, the many acts of courtesy and hospitality to the visiting
astronomers on the part of the townspeople will long be remembered by
the recipients.
The Smithsonian party proper consisted of thirteen observers,
and included Mr. Langley, Mr. Abbot, aid acting in charge of the
Smithsonian astrophysical observatory; Mr. Smillie, in charge of
photography; Mr. Putnam, of the United States Coast Survey; Mr. Fowle,
Mr. Mendenhall, Mr. Child, Mr. Draper, Mr. Gill, Mr. Kramer and Mr.
Smith. Included with these, the Rev. Father Searle and the Rev. Father
Woodman gave most valuable assistance. Mr. Hoxie, of Port Royal, S. C.,
and Mr. Little, of Wadesboro, rendered valued assistance to Mr. Putnam
during totality.
Professor Hale, of the Yerkes Observatory, was a member of the party,
while still in general charge of the Yerkes expedition, and his
counsel and aid were of the greatest service. Mr. Clayton, of Blue
Hill Meteorological Station, occupied a part of the grounds of the
Smithsonian party.
The main object of investigation was, of course, the corona, and of
this, (first) a photographic and visual study of its structure; with,
(second) a determination by the bolometer whether appreciable heat
reaches us from it, and, if possible, an examination of the form of its
spectrum energy curve.