D. S. (David Samuel) Margoliouth.

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almost arborescent vigor, over plain and mountain. These organisms
ai-e low in the vegetable hierarchy, and along with them may have
lived allied families : the microscopic Desmids and Diatoms, whose
siliceous tests showered down through the still oceans ; beside thera
the Corallines and Nulliporcs, forming calcareous fringes and coral-like
thickets ; the minute Protophytes and the delicate Charae. Doubtless
this age marked the climax of these plants, and, through multiplied
species and in vast numbers, they represented one phase of the ever-
restless evolution of vital forces.

The great deposits of iron-ore, though affording no direct evidence


in their remains of plant-life, are no less trustwortliy proofs of its
existence. They are themselves largely the result of vegetation in
some form. Dr, Hunt originally explained this connection, illustrating
it by identical processes in the world about us. If the reader visits a
bog-land in summer, where slowly-running or stagnant water collects
in pools, or if he stands upon the edge of a morass or marsh, he will
notice angular, iridescent films floating upon the surface. They are
thin pellicles of iron oxide, which will soon break up and sink, to be
succeeded by fresh "skins," which in turn disappear, building up a
growing layer of bog-iron ore beneath the water. The theory is simple.
Iron exists under two forms, a soluble or monoxide, and an insoluble or
sesquioxide. The latter is widely disseminated through the rocks and
soils. The insoluble modification is reduced to the monoxide or sol-
uble state in the presence of finely divided and rotting vegetable
matter, or in water charged with vegetable infusions, as emacerated
leaves and tissues. Rains and streams carry it away to lowlands and
depressions, where it becomes, through contact with the air, again oxi-
dized or rendered insoluble, and is redeposited in streaks and bands.
The widespread action of vegetable acids is here concerned. Humic,
crenic, apocrenic, and related acids, in conjunction with the reducing
power of carbonaceous residues, removed iron oxide from the original
rocks, and through the agency of water gathered it — useless as long as
it remained scattered in minute particles through vast terrains — into
enormous masses, the source and maintenance of our industries, thus
garnered through these gentle and silent methods. Such has been the
growth of the large deposits in the Marquette region, in the Adiron-
dacks, and at Pilot Knob — deposits which under the influence of heat
have become changed into the specular ores, the magnetites, and hema-
tites. They point unmistakably to the existence of plants, and no less
to their duration over immense periods of years.

The proofs of animal life are less satisfactory, and have been dis-
credited in high scientific writings, or, more accurately, the morpho-
logical types of that life have been rejected, leaving the general pre-
sumption unquestioned that animal life of some kind prevailed. In
the first place, the phosphatic minerals found in the archsean rocks are
considered derivative from organic remains, as to-day phosphorus as a
phosphate results from animal secretions, though phosphorus is omni-
present in the plant-world, and the ashes of various vegetables yield
from eight per cent, to fifty-three per cent, of phosphoric acid, while
the annual shipment of flour and wheat from our shores represents
thousands of tons of this element. In this respect the evidence does
not seem altogether controlling that these archtcan phosphates neces-
sarily resulted from animal debris. But the argument rests upon surer
grounds. In 18G5, Logan, Dawson, Carpenter, and Hunt, prepared a
paper of great merit upon an archajan fossil, which they named Eozobn,
and which they considered representative of the zoological sub-king-


dom of the Protozoa and allied to Forarainifera. They represent it as
an organism attaching itself by a gelatinous body to sea-floors, en-
veloping itself with a crust of carbonate of lime in which very small
tubes penetrated to the surface through which the sarcodous material
within projected in tapering fingers, to be withdrawn at the will of the
animal ; upon this another layer of protoplastic matter, formed in the
growth of the creature, connected with the first, but separated through-
out most of its extent by an interlamination of limestone, in which
radiating canals are discerned, and which succeeds the earlier porifer-
ous shell. Upon this new calcareous crusts arise, and thus a cellular
and tuberiferous mound is formed, compacted and regular, along the
base of attachment, but loose, granulated, and divergent at its summit.

In our present seas closely related organisms appear, the Rhizopods,
minute bodies, structureless, mere pellets of protoplasm, yet possessed
of a secretive function which incases them in exquisitely symmetrical
houses of lime. They are naturally low in the animal scale, indeed
primary, and the Eozo5n seems to have been a Titan progenitor of these
hosts of later protozoans whose numberless fragments form the chalk-
beds of England and France.

The Eozoon Canadense is found in the Laurentian rocks of Canada,
other species in the Huronian of Bavaria, and specimens have been
described from the Adirondacks and from Massachusetts. Forms
strikingly resembling Eozo5n may be found in the serpentine ledge in
Fifty-ninth Street, near Tenth Avenue, ^ew York. The soft parts in
the calcareous skeleton of this Rhizopod have been replaced by min-
erals, and on the resemblance, amounting almost to identity, between
the Eozoon and certain mineral pseudomorphs are based the objec-
tions made to its acceptance as of organic origin. King and Rowney,
of Dublin, and Mobius, of Germany, have very vigorously attacked it,
and lately Roemer rejects it from the list of paleozoic fossils. But it
seems impossible to doubt the reality of its animal arrangement. Pro-
fessor Hitchcock thoughtfully observes in this connection as regards its
resemblance to mineral replacements, " Inasmuch as these structures
represent the higher efforts of the mineral kingdom in crystallization
and the nearest approach to the inorganic world allowed by animal
forms, it is not strange that the two extremes should resemble each
other sufticiently to deceive practical observers."

This was, in a few words, the archtean Continent. Its greatest area
was in the north, with scattered islands and thin prolongations south-
ward along the present axes of elevation. Subsequent periods built
out from this and filled in the shadowy but prophetic sketch of North
America — not an azoic or lifeless country, as once thought, yet a terri-
tory where silence reigned, broken only by the roar of the surf along
its bleak margins, the whistle of the gale through its defiles, and the
thunder of tempests upon its plains. " Lonely, silent, and impassive,
heedless of man, season, or time, the weight of the Infinite seemed to
brood over it."





MA. MUNTZ, of the French National Agronomical Institute, an-
• nounces that he has discovered traces of alcohol as a natural
product in cultivated soil, rain-water, sea- and river-water, and the
atmosjjhere. He has detected the product, it is true, only in the most

Fio. 1.

infinitesimal quantities, but he has established the fact of its existence
by analyses which are at once simple, clear, and convincing.
* Translated from " La Nature."


= 39

He has submitted to distillation some fifteen or twenty litres, or
quarts, of snow-, rain-, or sea-water in the apparatus which is repre-
sented in Fig. 1. This apparatus consists of a milk-can, B, which is
made to serve as a boiler, in which the liquid to be distilled is put.
The vapors disengaged by the heat pass through a worm about thirty
feet long, in which they are resolved ; thence through a tube incased
in a refrigerating envelope, T, which is kept constantly cool by a cur-
rent of cold water ; and are then condensed in the glass receiver, R.
The operation is arrested as soon as one hundred or one hundred and
fifty cubic centimetres of liquid — which will contain all the alcohol —
have been condensed. The resultant liquid is again distilled in an

Fio. 2.— Chystals of Iodoform obtaiked by Svkthesis (greatly magnified).

apparatus similar to the former one, but smaller. The latter opera-
tion is arrested when some five or six cubic centimetres of liquid have
been condensed in a closed receiving-tube, which takes the place of
the receiver R in the former apparatus. The tube is then taken away,
and to its contents are added a little iodine and carbonate of soda ; on
heating it slightly, small crystals are precipitated of iodoform, a sub-
stance which could not be produced unless alcohol were present. M.
Muntz has verified the results of this process by other test experi-
ments. AVhen distilled water, chemically pure, was heated in the same
apparatus, the addition of iodine and carbonate of soda was not fol-
lowed by any reaction. A second verification was obtained by dis-
tilling fifteen litres of pure water, to which one millionth part of alco-
hol had been added ; the addition of iodine and carbonate of soda
caused a precipitation of iodoform precisely like that which was ob-


tained in treating the natural waters. One or two hundred grammes
(three and a half to seven ounces) of tilled earth mixed with a pint of

Fig. 3.— Crystals of Iodoform obtained with Kain-water.

water gave a similar precipitate of iodoform when distilled and ex-
posed to the reactions employed in the other experiments. The pre-

FiG. 4.— Crtstals of Iodoform obtained with Snow-wateb.

cipitation of iodoform by the addition of iodine and carbonate of
soda is a very evident test of the presence of alcohol. Iodoform


has marked characteristics which permit it to be distinguished very
readily : the form of its crystals, particularly, is typical ; it is of a
light yellowish color, and appears under the microscope in the form
of six-rayed stars derived from an hexagonal prism, of precisely the
form of snow-crystals. The accompanying figures give photographic
representations of the crystals as they appear under the microscope.
Fig. 2 represents the crystals from pure water to which alcohol has
been added in the proportion of one millionth ; Fig. 3, those ob-
tained from rain-water ; Fig. 4, crystals from snow-water ; and Fig.
5, those procured from cultivated soil. M. Miintz's first experi-
ments were made about four years ago. He has since examined a

Fig. 5. — Cbystaxs of Iodoform obtained with Cultivated Soil.

considerable number of samples of rain- and snow-water from Paris
and the country. After each distillation the apparatus has been care-
fully cleansed by exposing it for some time to currents of vapor, and
the analysis has been tested by repeating it in blank. More than
eighty essays have given identical results. The quantity of alcohol
contained in rain-, snow-, and sea-water may be estimated at from one
to several millionths of the whole. Cold water and snow-water seem
to contain a little larger proportion of it than warm water. Appreci-
able quantities of it are found in the water of the Seine ; and the pro-
portion is very sensibly increased in sewer-water. Vegetable mold
appears to be rich in it ; and it is probable that the natural alcohol
originates in the soil from the fermentation of the organic matters
contained in it, and is thence diffused as a vapor in the atrao-

VOL. XIX. — 16


sphere. Meteoric waters absorb it at the moment of their condensa-
tion. These results are absolutely new, to our knowledge, and are the
fruits of an entirely original labor.


By Professor H. IIELMHOLTZ.

THE majority of Faraday's own researches were connected, directly
or indirectly, with questions regarding the nature of electricity,
and his most important and most renowned discoveries lay in this field.
The facts which he has found are universally known. Nevertheless,
the fundamental conceptions by which Faraday has been led to these
much-admired discoveries have not been received with much consid-
eration. His principal aim was to express, in his new conceptions,
only facts, with the least possible use of hypothetical substances
and forces. This was really a progress in general scientific method,
destined to purify science from the last remnants of metaphysics.
Now that the mathematical interpretation of Faraday's conceptions
regarding the nature of electric and magnetic force has been given by
Clerk Maxwell, we see how great a degree of exactness and precision
was really hidden behind his words, which to his contemporaries ap-
peared so vague or obscure ; and it is astonishing in the highest de-
gree to see what a large number of general theories, the methodical
deduction of which requires the highest powers of mathematical analy-
sis, he has found, by a kind of intuition, with the security of instinct,
without the help of a single mathematical formula.

The electrical researches of Faraday, although embracing a great
number of apparently minute and disconnected questions, all of which
he has treated with the same careful attention and conscientiousness, are
really always aiming at two fundamental problems of natural philoso-
phy : the one more regarding the nature of physical forces, or of forces
working at a distance ; the other, in the same way, regarding chemical
forces, or those which act from molecule to molecule, and the relation
between these and the first.

The great fundamental pi-oblem which Faraday called up anew for
discussion was the existence of forces working directly at a distance
without any intervening medium. During the last and the beginning
of the present century the model after the likeness of which nearly all
physical theories had been formed was the force of gravitation acting

* The Faraday Lecture, delivered before the Fellows of the Chemical Societj in the
Theatre of the Royal Institution, London, on Tuesday, April 5, 1881, by Professor Helm-
holtz. Abstract revised by the author.


between the sun, the planets, and their satellites. It is known how,
with much caution and even reluctance, Sir Isaac Newton himself pro-
posed his grand hypothesis, which was destined to become the first
great and imposing example, illustrating the power of true scientific

But then came Oerstedt's discovery of the motions of magnets
under the influence of electric currents. The force acting in these
phenomena had a new and very singular character. It seemed as if it
would drive a single isolated pole of a magnet in a circle around the
wire conducting the current, on and on without end, never coming to
rest. Faraday saw that a motion of this kind could not be produced
by any force of attraction or repulsion, working from point to point.
If the cuiTent is able to increase the velocity of the magnet, the mag-
net must react on the current. So he made the experiment, and dis-
covered induced currents ; he traced them out through all the various
conditions under which they ought to appear. He concluded that
somewhere in a part of the space traversed by magnetic force there
exists a peculiar state of tension, and that every change of this tension
produces electro-motive force. This unknown hypothetical state he
called provisionally the electrotonic state, and he was occupied for
years and years in finding out what w^as this electrotonic state. He
discovered at first, in 1838, the dielectric polarization of electric insu-
lators, subject to electric forces. Such bodies show, under the influ-
ence of electric forces, phenomena perfectly analogous to those ex-
hibited by soft iron under the influence of the magnetic force. Eleven
years later, in 1849, he was able to demonstrate that all ponderable
matter is magnetized under the influence of sufticiently intense mag-
netic force, and at the same time he discovered the phenomena of dia-
magnetism, which indicated that even space, devoid of all ponderable
matter, is magnetizable ; and now, with quite a wonderful sagacity
and intellectual precision, Faraday performed in his brain the work of
a great mathematician without using a single mathematical formula.
He saw with his mind's eye that, by these systems of tensions and
pressures produced by the dielectric and magnetic polarization of space
which surrounds electrified bodies, magnets or wires conducting elec-
tric currents, all the phenomena of electro-static, magnetic, electro-
magnetic attraction, repulsion, and induction could be explained, with-
out recurring at all to forces acting directly at a distance. This was
the part of his path where so few could follow him ; perhaps a Clerk
Maxwell, a second man of the same power and independence of intel-
lect, was necessary to reconstruct in the normal methods of science
the great building, the plan of which Faraday had conceived in his
mind and attempted to make visible to his contemporaries.

Nevertheless, the adherents of direct action at a distance have not
yet ceased to search for solutions of the electro-magnetic problem.
The present development of science, however, shows, as I think, a


state of things very favorable to the hope that Faraday's fundamental
conceptions may in the immediate future receive general assent. His
theory, indeed, is the only existing one which is at the same time in
perfect harmony with the facts observed, and which at least does not
lead into any contradiction against the general axioms of dynamics.

It is not at all necessary to accept any definite opinion about the
ultimate nature of the agent which we call electricity.

Faraday himself avoided as much as he could giving any affirma-
tive assertion regarding this problem, although he did not conceal his
disinclination to believe in the existence of two opposite electric fluids.

For our own discussion of the electro-chemical phenomena, to
which we shall turn now, I beg permission to use the language of the
old dualistic theory, because we shall have to speak principally on re-
lations of quantity.

I now turn to the second fundamental problem aimed at by Fara-
day, the connection between electric and chemical force. Already,
before Faraday went to work, an elaborate electro-chemical theory
had been established by the renowned Swedish chemist, Berzelius,
which formed the connecting link of the great work of his life, the
systematization of the chemical knowledge of his time. His starting-
point was the series into which Volta had arranged the metals accord-
ing to the electric tension which they exhibit after contact with each
other. A fundamental point which Faraday's experiment contradicted
was the supposition that the quantity of electricity collected in each
atom was dependent on their mutual electro-chemical differences,
which he considered as the cause of their apparently greater chemical
affinity. But, although the fundamental conceptions of Berzelius's
theory have been forsaken, chemists have not ceased to speak of posi-
tive and negative constituents of a compound body. Nobody can
overlook that such a contrast of qualities, as was expressed in Berze-
lius's theory, really exists, well developed at the extremities, less evi-
dent in the middlq terms of the series, playing an important part in all
chemical actions, although often subordinated to other influences.

When Faraday began to study the phenomena of decomposition by
the galvanic current, which of course were considered by Berzelius as
one of the firmest supports of his theory, he put a very simple ques-
tion ; the first question, indeed, which every chemist speculating about
electrolysis ought to have answered. He asked, What is the quantity
of electrolytic decomposition if the same quantity of electricity is
sent through several electrolytic cells ? By this investigation he dis-
covered that most important law, generally known under his name,
but called by him the law of definite electrolytic action.

Faraday concluded from his experiments that a definite quantity
of electricity can not pass a voltametric cell containing acidulated
water between electrodes of platinum without setting free at the nega-
tive electrode a corresponding definite amount of hydrogen, and at the


positive electrode the equivalent quantity of oxygen, one atom of
oxygen for every pair of atoms of hydrogen. If, instead of hydrogen,
any other element capable of substituting hydrogen is separated from
the electrolyte, this is done also in a quantity exactly equivalent to
the quantity of hydrogen which would have been evolved by the
same electric current.

Since that time our experimental methods and our knowledge of
the laws of electrical phenomena have made enormous progress, and a
great many obstacles have now been removed which entangled every
one of Faraday's steps, and obliged him to fight with the confused
ideas and ill-applied theoretical conceptions of some of his contempo-
raries. We need not hesitate to say that, the more experimental
methods were refined, the more the exactness and generality of Fara-
day's law was confirmed.

In the beginning, Berzelius and the adherents of Volta's original
theory of galvanism, based on the effects of metallic contact, raised
many objections against Faraday's law. By the combination of No-
bili's astatic pairs of magnetic needles with Schweigger's multiplicator,
a coil of copper wire with numerous circumvolutions, galvanometers
became so delicate that the electro-chemical equivalent of the smaller
currents they indicated was imperceptible for all chemical methods.
With the newest galvanometers you can very well observe currents
which would want to last a century before decomposing one milligramme
of water, the smallest quantity which is usually weighed on chemical
balances. You see that, if such a current lasts only some seconds or
some minutes, there is not the slightest hope to discover its products
of decomposition by chemical analysis. And, even if it should last a
long time, the feeble quantities of hydrogen collected at the negative
electrode can vanish, because they combine Avith the traces of atmos-
pheric oxygen absorbed by the liquid. Under such conditions a feeble
current may continue as long as you like without producing any visible
trace of electrolysis, even not of galvanic polarization, the appearance
of which can be used as an indication of previous electrolysis. Gal-
vanic polarization, as you know, is an altered state of the metallic
plates which have been used as electrodes during the decomposition of
an electrolyte. Polarized electrodes, when connected by a galvanom-
eter, give a current which they did not give before being polarized.
By this current the plates are discharged again and returned to their
original state of equality.

This depolarizing current is indeed a most delicate means of dis-
covering previous decomposition. I have really ascertained that un-
der favorable conditions one can observe the polarization produced
during some seconds by a current which decomposes one milligramme
of water in a century.

Products of decomposition can not appear at the electrodes without
motions of the constituent molecules of the electrolyte throughout the


whole length of the liquid. This subject has been studied very care-
fully, and for a great number of liquids, by Professor Hittorff, of
Milnster, and Professor G. Wiedemann, of Leipsic.

Professor F. Kohlrausch, of Wilrzburg, has brought to light the
very important fact that, in diluted solutions of salts, including hy-
drates of acids and hydrates of caustic alkalies, every atom under the
influence of currents of the same density moves on with its own pecul-
iar velocity, independently of other atoms moving at the same time
in the same or in opposite directions. The total amount of chemical
motion in every section of the fluid is represented by the sum of the
equivalents of the cation gone forward and of the anion gone back-
ward, in the same way as in the dualistic theory of electricity, and the
total amount of electricity flowing through a section of the conductor

Online LibraryD. S. (David Samuel) MargoliouthThe Popular science monthly (Volume 19) → online text (page 30 of 110)