GIFT OF

THE SCIENTIFIC WORK

OF

MORRIS LOEB

THE SCIENTIFIC WORK

OF

MORRIS LOEB

THE SCIENTIFIC WORK

OF

MORRIS LOEB

FORMERLY PROFESSOR OF CHEMISTRY AND

DIRECTOR OF THE HAVEMEYER CHEMICAL LABORATORY

AT NEW YORK UNIVERSITY

EDITED BY

THEODORE W. RICHARDS

PROFESSOR OF CHEMISTRY AND DIRECTOR OF

THE WOLCOTT GIBBS MEMORIAL LABORATORY

AT HARVARD UNIVERSITY

CAMBRIDGE

HARVARD UNIVERSITY PRESS
1913

COPYRIGHT, 1913, BY HARVARD UNIVERSITY PRESS
ALL RIGHTS RESERVED

PREFACE

THIS volume is published as a memorial to Morris Loeb,
a man of rare gifts who was called in his prime from his
many-sided activities. The book will serve to make more
accessible the thoughtful and suggestive writings of one of
the American pioneers of the new physical chemistry.

All the publications of the late Professor Loeb bearing
upon scientific topics have here been brought together,
except a few brief reviews in Italian possessing only tran-
sient interest; and there have been added such parts of
several essays found in manuscript as he might have been
willing to have printed. The collected papers have been
divided into two groups; the first includes those of a gen-
eral character (such as essays, lectures, and reviews), and
the second those recording the results of his original experi-
mental researches, which are more technical in their nature
and less generally comprehensible. This division into two
groups was made in order that essays having general interest
should not be lost to the average reader by being hidden
among scientific papers beyond his comprehension.

In each group the papers have been arranged in chrono-
logical order. Of those found in manuscript, parts of three
discussions of the same subject have been welded together so
as to make one consistent essay and placed at the beginning
of the first group under the title "The Fundamental Ideas
of Physical Chemistry." The first part of this essay was
evidently given as the introductory lecture of a course on
physical chemistry at Clark University in 1889. Each of
the three papers was fragmentary; but fortunately the gaps

271811

vi PREFACE

occurred in different places, so that it was possible to con-
struct almost entirely in the author's own words a fairly
consistent whole. Although these fragments were not deemed
worthy of publication by their author, and although doubt-
less he would have preferred to revise them before printing,
it has seemed worth while to publish them because they
formed one of the very first presentations of the new phys-
ical chemistry on this side of the Atlantic.

The popular address on "Atoms and Molecules " also was
found in manuscript, and like the preceding essay, has had
incorporated into it several scattered paragraphs upon the
same subject from other incomplete notes. Thus it is hoped
that all of his written work on this subject that is worthy
of printing has been preserved in readable form.

Another paper printed for the first time is that on Sir
Isaac Newton, which is of interest in showing the author's
appreciation of the value of abstract scientific research.

The only other important paper found in manuscript
(placed under the title " Chemistry and Civilization," at the
end of the first group of papers) was intended by Professor
Loeb to be the introduction to a proposed comprehensive book
upon the usefulness of the science in its widest sense. Upon
this book he was working at the time of his death ; and one
cannot but poignantly regret, after reading the introductory
chapter, that the completion of the project was denied him.

Two of the researches included in the second group were
published both in German and in English; in these cases both
versions are reprinted, because the translations are evidently
the author's work, and differ in several details from the
originals.

In each of the scientific articles included in the second
part of the book, the page numbers of the original publica-
tion are inserted in brackets at the proper places, to show

PREFACE vii

where each page begins and ends. This is done for the con-
venience of commentators wishing to refer to the original
articles. All the papers have been reprinted essentially in the
form used by the author. The historical advantage of this
practice is obvious; and although usage in nomenclature,
notation, and spelling has somewhat changed during twenty-
five years, the older forms cannot in any of the present
instances give rise to misunderstanding.

After the scientific contributions, Professor Loeb's labora-
tory manual of experiments for the elementary course in
inorganic chemistry at New York University is printed as an
appendix, together with the description of a brief series of ex-
periments upon the speed of reactions. These are included
not only for the sake of completeness, but also because they
may be suggestive to others confronted with the interesting
but difficult task of giving elementary instruction.

A complete chronological list of all the separate essays is
given at the end of the volume, with the references to the
original sources; and an index of names completes the book.

Other manuscripts and notebooks found in his laboratories
contained much that was almost ready for publication, but
probably nothing more that he himself would have con-
sidered as ready to appear in print. The preliminary search
among these papers was conducted at the request of his
family by Professor Charles Baskerville, of the College of the
City of New York, and Mr. D. D. Berolzheimer, a former
student of Professor Loeb's and the librarian of The Chemists'
Club; thanks are due to both for their valuable assistance in
making a preliminary selection and arrangement of the ma-
terial, and to the latter, as well as to Professor G. S. Forbes,
for their help in reading the proofs. To Professors Charles
Loring Jackson, Elmer P. Kohler and Gregory P. Baxter
also the editor is grateful for advice. T. W. R.

CONTENTS

INTRODUCTION: THE LIFE AND CHARACTER OF MORRIS LOEB . . xv

PART I
LECTURES, ADDRESSES, AND REVIEWS

THE FUNDAMENTAL IDEAS OF PHYSICAL CHEMISTRY .... 3

OSMOTIC PRESSURE AND THE DETERMINATION OF MOLECULAR
WEIGHTS 21

ELECTROLYTIC DISSOCIATION: A REVIEW OF THE HYPOTHESIS OF
SVANTE ARRHENIUS 30

REVIEW OF OSTWALD'S GRUNDRISS DER ALLGEMEINEN CHEMIE . 45

THE PROVINCE OF A GREAT ENDOWMENT FOR RESEARCH ... 46

ATOMS AND MOLECULES 50

HYPOTHESIS OF RADIANT MATTER 64

REPORT OF THE COMMITTEE OF THE OVERSEERS TO VISIT THE

CHEMICAL LABORATORY OF HARVARD COLLEGE .... 78

THE CONDITIONS AFFECTING CHEMISTRY IN NEW YORK ... 93

SIR ISAAC NEWTON 101

OLIVER WOLCOTT GIBBS 108

THE CHEMISTS' CLUB, NEW YORK 118

THE CHEMISTS' BUILDING 121

ADDRESS AS PRESIDENT OF THE CHEMISTS' BUILDING COMPANY . 128
THE COAL-TAR COLORS . . 132

x CONTENTS

THE PERIODIC LAW 143

THE EIGHTH INTERNATIONAL CONGRESS OF APPLIED CHEMISTRY . 152
CHEMISTRY AND CIVILIZATION 156

PART II
ORIGINAL EXPERIMENTAL INVESTIGATIONS

UEBER DIE EINWIRKUNG VON PHOSGEN AUF AETHENDIPHENYL-
DIAMIN 169

UEBER AMIDINDERIVATE 171

DAS PHOSGEN UNO SEINE ABKOMMLINGE NEBST EINIGEN BEITRAGEN

zu DEREN KENNTNISS 177

DAS PHOSGEN: LITTERATUR-VERZEICHNISS 205

DAS PHOSGEN: EXPERIMENTELLER THEIL 209

THE MOLECULAR WEIGHT OF IODINE IN ITS SOLUTIONS . . .230
UEBER DEN MOLEKULARZUSTAND DBS GELOSTEN JODS . . . 239

THE USE OF ANILINE AS AN ABSORBENT OF CYANOGEN IN GAS
ANALYSIS 248

ZUR KlNETIK DER IN LoSUNG BEFINDLICHEN KORPER . . .251

THE RATES OF TRANSFERENCE AND THE CONDUCTING POWER OF

CERTAIN SILVER SALTS 273

THE USE OF THE GOOCH CRUCIBLE AS A SILVER VOLTAMETER . 293
Is CHEMICAL ACTION AFFECTED BY MAGNETISM? 295

APPARATUS FOR THE DELINEATION OF CURVED SURFACES, IN ILLUS-
TRATION OF THE PROPERTIES OF GASES, ETC 306

NOTE ON THE CRYSTALLIZATION OF SODIUM IODIDE FROM ALCO-
HOLS 308

THE VAPOR FRICTION OF ISOMERIC ETHERS 310

ANALYSIS OF SOME BOLIVIAN BRONZES 312

STUDIES IN THE SPEED OF REDUCTIONS .... 314

CONTENTS xi

APPENDIX

LABORATORY MANUAL PREPARED FOR STUDENTS IN ELEMENTARY
INORGANIC CHEMISTRY AT NEW YORK UNIVERSITY .... 321

EXPERIMENTS ON SPEED OF REACTION 338

CHRONOLOGICAL BIBLIOGRAPHY 340

INDEX OF NAMES . . 345

LIST OF ILLUSTRATIONS

MORRIS LOEB Frontispiece

WOLCOTT GIBBS MEMORIAL LABORATORY, HARVARD

UNIVERSITY opposite page 92

THE CHEMISTS' BUILDING, 52 EAST FORTY-FIRST STREET,

NEW YORK opposite page 118

THE LIFE AND CHARACTER OF MORRIS

LOEB

IN the untimely death of Morris Loeb our country lost a
man of rare quality. To serve mankind was the ideal of his
life, and loyalty was his guide in the fulfillment of this service;
few men in so short a span of years have been able to ex-
press so largely their desire by deeds. His helpful acts and
liberal benefactions were modestly carried out; they were
perhaps hardly appreciated in their fullness during his life-
time by any except those who came nearest to him. As an
ameliorator of the lot of the poor of New York he was in the
front rank; at the same time he was a farseeing enthusiast
in the cause of science, and one of the most faithful and
generous graduates of Harvard University. His devotion
to his Alma Mater makes it especially appropriate that this
volume of his writings should appear under her auspices.

Among his various interests chemistry was foremost, al-
though the responsibilities of a great fortune and its attendant
demands prevented him from devoting as much time to re-
search as he would have been glad to give. The study of his
work as disclosed in the following pages will show a mental
attitude unusually thoughtful and philosophic, alive to new
ideas and yet wisely conservative. His conservatism was not
of a reactionary type, because he was ever altruistic in his
point of view. His constant aim was to support that which
seemed to him likely to contribute, either through the ad-
vance of science or in any other way, to the good of mankind.

Morris Loeb was born fifty years ago at Cincinnati, Ohio,
on May 23, 1863, the son of Solomon and Betty (Gallenberg)
Loeb. His father was one of the founders of the great bank-

xvi THE LIFE AND CHARACTER

ing firm of Kuhn, Loeb and Company. While the boy was
still young, his parents removed to New York, and his
primary education took place at the school of Dr. Julius Sachs
in that city. In the autumn of 1879 he entered Harvard Uni-
versity and graduated there with the degree of Bachelor of
Arts in 1883.

He was an able and conscientious student in college. His
interest centred at first in the older discipline of the classics,
but it changed to the newer discipline of chemistry and phys-
ics as his college life advanced. His experience under Charles
Loring Jackson in "Chemistry 1 " during his Freshman year
seems to have awakened that love of science which, fostered
as it was by Wolcott Gibbs in his later years, determined his
life work. As an undergraduate he received a "Detur" or
prize for high scholarship, and at graduation he attained
his degree "Magna cum Laude" on his general average, as
well as with "Honorable Mention" in chemistry and English
composition. His best chemical work in college was done in
the field of organic chemistry under Henry Barker Hill,
and this interest was continued in his studies immediately
afterwards in Germany, as is evidenced in his first two scien-
tific papers.

During the period of his stay in Berlin, where he studied
under August Wilhelm von Hofmann and received the de-
gree of Ph.D. in 1887, the new interest in physical chemistry
had risen above the intellectual horizon of Germany, and
Loeb's farsighted intelligence at once grasped the significance
of the coming science. The winter after he received his de-
gree, he entered the University of Heidelberg for the study
of physical chemistry, and during the following summer he
attended the University of Leipzig, working under the bril-
liant new leader, Wilhelm Ostwald, and in collaboration with
his able assistant, Walther Nernst.

OF MORRIS LOEB xvii

In the autumn of 1888 Loeb returned to America; he was
now so thoroughly imbued with a passionate love for science
that the urgent appeal of the brilliant position in banking
which was open to him was not heeded. Instead of turning
towards finance he entered upon a voluntary private assistant-
ship under Wolcott Gibbs, who had recently retired from his
Rumford Professorship in Harvard University and as Pro-
fessor Emeritus had established a private chemical laboratory
near his house at Newport, Rhode Island. Their mutual
affection, which had begun years before when both were at
Harvard, was intensified by this close association; and it is
typical of the characteristic faithfulness of Loeb's nature
that nearly a quarter of a century afterward he should have
suggested the naming of a new laboratory for research,
founded at Harvard by him and his brother James Loeb
(of the class of 1888), in honor of Gibbs.

In 1889 the young physical chemist was appointed to a
docentship in Clark University. His opening lecture there
was probably the essay given first among the papers included
in this volume; he never published it himself, but the man-
uscript remains in his own handwriting. This lecture shows
his intelligent appreciation of the main problems of the new
physical chemistry and their great importance. He was in-
deed one of the pioneers in America in this new field of
science, and his influence was far-reaching.

In 1891 he was elected to a professorship of chemistry in
New York University, and four years afterwards became direc-
tor of the chemical laboratory there, an office which he held
for eleven years. His resignation in 1906 was due not to any
weakening of his interest in chemistry, but rather to the pres-
sure of countless other demands upon his time, which made
the routine of such a position almost if not quite impossible.

Much of his energy was given to a number of charitable

xviii THE LIFE AND CHARACTER

organizations; for his keen sympathy with human suffering
caused him to be ever responsive to the needs of the un-
fortunate. His charitable work, like his generous activity in
other directions, was by no means restricted to his own race,
although he was of course especially devoted to associations
which had as their object the improvement of the lot of the
great mass of Hebrew poor in New York. He was president
of the United Jewish Charities Building, a member of the
American Jewish Committee, a trustee of the Jewish Theologi-
cal Seminary of America, and was at one time president of
the Jewish Agricultural and Industrial Aid Society. He was,
moreover, president and one of the founders of the Solomon
and Betty Loeb Home for Convalescents, erected in mem-
ory of his parents.

Another enterprise demanding much of his time was The
Chemists' Club of New York, the welfare of which he did
much to promote. Here again he was characteristically earn-
est in his effort to help in every possible way those for whom
he felt himself especially responsible. Twice he was vice-
president and twice president of the club, and it was during
his first presidency in 1909 that the idea of housing the
club and its admirable library in a dignified building first
took shape. He not only gave outright many things to the
unique building which rose under his direction, but also was
one of the chief stockholders in the enterprise. His generous
bequest of all his holdings of stock in the building to the
Chemists' Building Company for cancelation cannot but do
much to fortify the future of the Club and help towards its
permanent existence.

In 1908 he was appointed one of the committee of the Har-
vard Overseers to visit the Chemical Laboratory. As usual he
entered very faithfully into this new responsibility and, unless
in foreign lands, attended every meeting of the committee,

OF MORRIS LOEB xix

although such attendance involved on each occasion a trip
to Boston. Besides making this sacrifice of time and energy
in behalf of his beloved University, he bore always in mind
the difficulties of the struggling Division of Chemistry, and
frequent letters, often written in his own hand from remote
countries, brought valuable suggestions to the department
and attested his constant interest in its welfare and in the
growth of his chosen branch of science at Harvard. As al-
ready stated, it was upon his initiative, through the generous
gift of $50,000 from his brother James Loeb and himself,
that the Wolcott Gibbs Memorial Laboratory for research
in physical and inorganic chemistry was founded at Harvard.

Largely through his interest and endeavor the Association
of Harvard Chemists was formed, from among the alumni of
the University; and his hospitality to this association during
the Eighth International Congress of Applied Chemistry in
1912 will long be remembered by those who were fortunate
enough to be his guests at that time.

His devotion to the Congress was characteristically strong.
Since delegates from all over the world had been invited to
this continent, he felt that Americans should take especial
pains to make the meeting a success. Although he had only
just returned from a long trip to South America, undertaken
with the hope of stimulating interest in the undertaking, he
threw himself with self-sacrificing enthusiasm into the work
of preparing for the reception of the foreign guests in Wash-
ington and New York.

Besides being a member of the Congress (and an unusually
helpful one), Professor Loeb was a fellow of the New York
Academy of Sciences and of the American Association for
the Advancement of Science, and a member of the Amer-
ican Chemical Society, the German Chemical Society, the
American Electrochemical Society, and the New York Elec-

xx THE LIFE AND CHARACTER

trical Association. He received the honorary degree of Doc-
tor of Science from Union College in 1911.

During the twenty-nine years between his graduation and
his death, Morris Loeb published thirty papers, reviews,
and essays. Many of these depended upon experimental work
carried out at the universities in Berlin, Heidelberg, Leipzig,
Worcester, and New York, or in the private laboratories
which he himself established, after his retirement from active
teaching, in New York and on his beautiful country estate
at Sea Bright, New Jersey. For the reasons already set
forth, the extent and scope of his experimental researches
were far less than he wished; but, even so, the work forms a
sum total of which any one might be proud.

His investigations dealt with a wide variety of topics and
showed a steadily increasing desire to penetrate further into
the fundamental mysteries of the nature and mechanism of
chemical reaction. To those not conversant with the subject
it would be impossible here to explain the purport of these
investigations, and to those familiar with its details the
papers speak for themselves. No one can turn the pages
without the conviction that this work was carried out with
the earnest desire, which marks the sincere man of science,
to discover the truth and nothing but the truth.

Morris Loeb's vivid interest in the advance of science did
not preclude an intelligent appreciation of achievement in
other fields of human activity. He was deeply interested in
music and art, and was one of the founders and endowers
of the Betty Loeb Musical Foundation. Himself a teacher
for years, he was greatly interested in all educational causes.
For several years he was a director of the Educational Alli-
ance, and at the time of his death he was a member of the
Board of Education of New York City and president of the
Hebrew Technical Institute.

OF MORRIS LOEB xxi

On April 3, 1895, he was married at Cincinnati, his native
city, to Miss Eda Kuhn, who survives him. After more than
seventeen years of devoted married life, he died on October
8, 1912, falling a victim to typhoid fever and double pneu-
monia. He was a martyr to his noble ideal of service; for one
cannot but believe that the way for his fatal illness was paved
by his over-exertion in welcoming at Washington the mem-
bers of the International Congress. The interment in the
family vault at Salem Fields, Cypress Hills, Long Island,
took place in the presence of a sorrowing throng of men and
women of many creeds and stations.

The esteem in which he was held is manifest in the many
deeply appreciative resolutions now spread upon the records
of the societies of which he was a member. From among these,
two are quoted below, as typical of the general recognition
of his worth.

, At the meeting of the Trustees of The Chemists' Club on
the day of his death, the following preamble and resolution,
drawn up by Ellwood Hendrick, Clifford Richardson, and
Walter E. Rowley, were adopted: —

"WHEREAS, Morris Loeb, the President of the Club, has
been taken from us by death; and

"WHEREAS, he was the leading spirit in bringing to ful-
fillment ambitions and plans that had long been ours; and

"WHEREAS, he was always ready to shoulder burdens and
to give help; and

"WHEREAS, he was a man of order, and of integrity,
in mind and heart, sincere in scholarship, living without
malice or scorn, speaking no evil, and generous in judgment;
and

"WHEREAS, we were drawn to him by ties of deep and
abiding affection; now, therefore, be it

"Resolved, that we make this minute of our poignant grief

xxii THE LIFE AND CHARACTER

at his passing, and that we cherish his memory as another of
his great gifts to science and to humanity."

The following sentences, written by Marston T. Bogert,
Charles F. Chandler, and William H. Nichols, and entered
upon the minutes of the New York Section of the Society of
Chemical Industry, express again the general appreciation
of his life and character: —

"Morris Loeb, chemist, investigator, educator, upright
and useful citizen, altruist, philanthropist, generous patron
and benefactor of art, of sciences, and of all good works, ever
ready to bear more than his share of the burdens of the com-
munity and always to be found on the side of righteousness,
justice, and truth, lived his life of quiet power without arro-
gance or display. Always modest concerning his own dis-
tinguished career and many accomplishments, with charity
towards all and unkind criticism of none, he was ever
a courteous, genial, and polished gentleman of high ideals,
whose chief aim and purpose was to be of assistance to his
fellow-men, and who realized to the full that the highest
reward of service is the privilege of having been of service.

"Now that the temporary scaffolding of life has fallen
away, the true nobility of his character stands clearly revealed
in all its commanding beauty and dignity, an imperishable
monument of a life's work well done and a worthy inspiration
to others. Such manhood is the real glory to any country.
The world is the better for his having lived in it, and we are
the better for having known him."

Any statement of the good wrought by this ardent worker
in the cause of science regarded as an agent for human ad-
vancement would be incomplete without allusion to several
of the provisions of his will. By it he assured, as has been
already said, the permanence of The Chemists' Club as a

OF MORRIS LOEB xxiii

centre of chemical influence in the country; he provided for
the establishment of a museum of rare and typical substances
to be maintained by the American Chemical Society; and,
most important of all, he bequeathed a fund of $500,000
to be used eventually by Harvard University for the fur-
therance of the sciences of chemistry and physics.

These provisions, like many of his earlier benefactions,
will bear blessings far into the future; the fruit of his contribu-
tions to the welfare of humanity will multiply.

In Morris Loeb's life and character our country and
Harvard University have a right to take deep pride. Up-
right, unselfish, generous, loyal, sincere, wise, and modest, he
set a noble example; his memory is treasured by all who had
the privilege of knowing him. When those too have left this
earthly life, he will be kept in remembrance by his great gifts
to science and to charity, and be honored by many generations
in the years to come.

THEODORE W. RICHARDS.

PART I

LECTUBES, ADDRESSES, AND REVIEWS

THE FUNDAMENTAL IDEAS OF PHYSICAL
CHEMISTRY1

IN commencing this course of lectures, whose subject-
matter and title are avowedly new to the American student,
I feel the need of giving some justification, of presenting
some reason why I should seek to add one more round to the
ladder of learning already so alarmingly long. To-day, the
cry against specialization is increasingly raised; and we now
and then hear voices wailing for the good old times, when an
Admirable Crichton could boast of knowing something of
all things knowable, and when a Pico della Miranqlola could
publish his readiness to dispute against all comers, "de
omnibus rebus."

But wishing these times back will not recall them. Loosed
from the leash of rhetoric and dogmatism, the pursuers of
knowledge have spread in all directions over the field, each
so eager on his own particular trail that he has no eye for the
discoveries of his neighbor; he forgets, indeed, that there is
need of keeping in touch to the right and left, lest important
clues be passed unobserved. No wonder if the bewildered
spectators should think that the whole pack has gone mad,
and that the majority, at least, have been diverted, by their
own self-sufficiency, from the noble quarry upon which they
had been set. Nevertheless, we may already see a change
in their methods: they are shaping their courses parallel to
each other, they strive to keep abreast and neighbors in-
stead of running apart; they carefully scan the ground
between themselves, that nothing may lurk there unseen.

1 Introductory lecture of a course probably given at Clark University in 1889.

MORRIS LOEB

To speak in more sober language, while it is still necessary
for the advancement of knowledge that investigators should
concentrate their energies on their particular fields of science,
these various branches are now approaching so close together
that one will aid the other, if properly directed. While, there-
fore, it would be preposterous to demand of the anatomist
a full knowledge of astronomy, or to ask a geologist for his
opinion of the various hypotheses concerning the structure
of benzol, we may justly deride the man who confines him-
self so closely to his own particular hobby that he remains
ignorant of those subjects which are neighboring links in the
chain of knowledge, merely because he does not expect aid
from them. Such men may be most skillful in delving for
new facts, they may light upon discoveries which will make
their names famous, fill their pockets, cover their breasts with
decorations, and stuff their cabinets with diplomas. But the
actual merit of incorporating these facts into the world's
knowledge will belong to him who, with a wider view, will
connect them with other isolated facts to form a harmonious
whole.

Especially has our own science been unfortunate in pro-
ducing hundreds of specialists of the narrowest order. The
ever-increasing number of subjects which claim attention,
the perplexing rapidity with which new views supersede
older ones, the restriction which the work in the laboratory
places upon our time, — these have all had a share in per-
suading chemists to confine their attention to a narrow field
and to give scanty hearing to that which does not concern
their own particular work. But, worse still, we have to con-
tend with the opinion that chemistry is a practical science,
that it is our chief glory to produce new compounds of un-
heard-of intricacy, that our recompense is to be sought in
some discovery which will have a commercial value. Far be it

IDEAS OF PHYSICAL CHEMISTRY 5

from me to detract from the merits of a Liebig, a Hofmann, a
Horsford, a Deville; the discoveries by which they have
enriched mankind are among the brightest ornaments of our
science. But the brilliancy of their achievements has so
dazzled the eyes of the world as to lead men into the danger
of forgetting that the true duty of a science is the investiga-
tion of natural phenomena, and that the employment of
known forces for the production of effects which, however
novel and beautiful, depend merely on ingenious combina-
tions, must soon bring chemistry to the level of an art. Too
many chemists hurry in their studies toward the El Dorado
of carbon synthesis, striving to obtain at the earliest mo-
ment tangible results in the shape of new substances, be they
dyes, drugs, or merely triumphs of synthetical art. In this
eager chase they rush heedlessly over the rich fields of
stoichiometry, of inorganic chemistry, of analysis, of electro-
chemistry, of the problems of chemical affinity.

Like to the miners of '49 the specialist in organic chemistry
has but one thought. Arrived at his diggings, he delves as-
siduously, and if favored by fortune and skill is rewarded with
many a rich nugget. But if, resting awhile from his labors
he decides to retrace his steps and revisit former scenes, he
is astounded to find that lands passed by as cheerless and
barren have been occupied by settlers, who with patience
and care have cultivated and beautified them, and are now
reaping wealth more lasting and productive than his own gold.

Let us, then, who have not staked our claims, travel more
leisurely, tarrying here and there, surveying our fair inherit-
ance and considering whether it be not our duty to turn aside
from the main road,1 in order that we may render fruitful
that which would else be a noisome desert.

1 In 1889 this "main road" was the study of synthetic organic chemistry.
[Editor.]

6 MORRIS LOEB

Chemistry, as I have intimated, owes its great prominence,
in popular estimation, to those material successes of the
branch called organic chemistry, which have rapidly suc-
ceeded each other during the last thirty years. Their founda-
tion was laid by that grand work of systematization, with
which we find connected the most glorious names of modern
chemistry, Liebig and Wohler, Laurent and Gerhardt,
Dumas, Hofmann, Wurtz, Williamson, Couper, Kekule, and
Cannizzaro. So extensive and intricate is this system, and
yet so fruitful in all its ramifications, that it has well repaid
the intense labor bestowed upon it by these men and the hosts
of their pupils and successors. But we must not lose sight of
the fact that, after the first successful generalizations, the
work has been mainly deductive and not inductive. We have
had an algebra devised for us with its own notation and its
own processes of reasoning: it remains for us to combine these
ingeniously, so that they may apply to the special problems
with which we are confronted. Our success is so great, that
it appears that the propositions upon which we started are
axiomatic instead of hypothetical, and general instead of
special; so that, when we have quoted one of them, we believe
that we have stated the first principle to which any question
can be referred. As a matter of fact, organic chemistry by it-
self only clears up the questions of composition and consti-
tution and of change within the molecule. The interesting
problems as to the nature of what we call atoms, the prop-
erties of the elements, the peculiar behavior of the molecules
toward each other, and — grandest problem of physical sci-
ence — the correlation of matter and energy, do not present
themselves to the organic chemist. We shall have occasion
to see how reluctant he is to accept other explanations than
those given by his formulae for phenomena which these
formulae seem incapable of explaining fully.

IDEAS OF PHYSICAL CHEMISTRY 7

Turning now to inorganic chemistry, we find it completely
overshadowed by its younger rival: its votaries are few and
disheartened. I think that I do no injustice in asserting that,
for most students, the mention of this study conveys no idea
but that of laborious quantitative analysis for commercial
and mineralogical purposes. That subdivision which corre-
sponds more closely to organic chemistry, the description
and natural history of the elements and their compounds, is
generally taught chemical students at the very beginning of
their course of study, and must naturally appear to be ele-
mentary and of least importance and interest. They may
indeed also recollect dimly some few introductory lectures,
given as a necessary evil and listened to with imperfect com-
prehension, about the atomic and molecular theories, the na-
ture of reactions and the physical properties of compounds,
but these also are for the most part hidden in the mists of the
past.

Do not understand me as saying that all these subjects
have not had skillful investigators during the last thirty years.
This is by no means the case; we shall come across many re-
vered names in the course of our review. The trouble is that
their work has not received that attention from the whole
community of chemists, which would make it as commonly
known as are the achievements of organic synthesis, and place
it upon its proper pedestal for public admiration. Why should
we know less about silicon, iron, and sulphur, than we know
about carbon, hydrogen, oxygen, and nitrogen? Why should
we care more about the color, melting-point, and boiling-
point of a compound than we do about its behavior towards
other manifestations of energy beside light and heat? Above
all, why should we confine ourselves to the internal consti-
tution of molecules, when we should also concern ourselves
with their behavior toward each other, with those mysteries

8 MORRIS LOEB

of affinity and reaction which cannot be explained by merely
paraphrasing the phenomena? Not merely book-learning
may be acquired by this knowledge; it continually furnishes
us with new weapons for the further investigation of truth.

Gentlemen, the interest in general and physical chemistry
is reawakening, and we may soon hope to see these studies as
prominent as they were in the times of Humphry Davy and
Gay-Lussac, of Berthollet and Dalton, of Berzelius and of
Michael Faraday. I am thankful that this new university
has granted me an opportunity of calling attention to them
in our country; and I shall be happy indeed if I can augment
in you the love for this branch of speculative philosophy,
by pointing out some recent achievements and showing how
much still remains to be done.

Confronted with the necessity of defining the scope of
chemistry, I would say: Chemistry is that branch of Physics
which treats of the differentiation of matter. Treading gin-
gerly on the dangerous ground of metaphysics, we may re-
cognize that there are four principles to which the educated
mind refers natural phenomena, — four first causes, four
categories, four systematic axes, — namely: energy, matter,
space, and time. The practice of referring all outward im-
pressions to these ultimate principles is undoubtedly a great
advance over the assumption of the cruder "elements" of
the Middle Ages, earth, air, fire, and water; but even energy,
matter, space, and time are not by any means ideas to which
we attach a definite, unalterable meaning. Their definition
seems to vary in different minds and at different times in the
same mind. Some prefer to consider time a mode of space,
and others consider both time and space attributes of matter
and energy, but not as independent essentials. All that we
can say of energy and matter is that they exist, at least to
our perceptions. We are apt to consider matter as some-

IDEAS OF PHYSICAL CHEMISTRY 9

thing more tangible and material than energy, but this is be-
cause we confound substance with matter. In fact, we are
no more acquainted with matter than with energy. We know
matter by its reaction with energy, and energy by its re-
action with matter. Since one thus defines and differentiates
the other, we are moving in a vicious circle, and must pretty
well despair of reaching, upon physical grounds, a perfect
view of the real essence of either. Matter must, however, be
defined for our purposes, and let us therefore frankly regard
it as Aristotle did, the v\r}9 or stuff, from which the Universe
is shaped as is the house from timber, or pottery from clay.

Whether this ultimate matter is homogeneous or not, we
have no means of knowing, but our instinctive love of sim-
plification leads us to suppose that it is homogeneous and one.
This, however, is a purely hypothetical assumption. When
we make an impartial study of fact, we find that by com-
bining certain portions of matter with certain portions of
energy, we obtain what is known as substance, and this may
appear in infinitely different forms. It will seem odd to you
that I should define substance as a combination of matter
and energy, but a little reflection will show you that this view
is quite admissible. All substances show certain qualities
which are referable to energy, and may be considered as a
combined phenomenon of matter and energy. Thus we are
almost unable to imagine substance without the energy of
gravitation, of motion, of chemical affinity.

Modern physics teaches us that energy is one, inasmuch as
each form of energy is convertible into every other form, in
certain definite quantitative ratios. The instinct of the al-
chemists told them that all matter was one, and each form
was convertible into every other form. If this were the
modern aim of chemistry, we should be obliged to confess
that very little has been accomplished as yet. We have

10 MORRIS LOEB

reached a class of about sixty-five substances, which we have
not yet been able to decompose or transform, and which we
call the elements. True, many chemists believe that these
elements are themselves composite, but whether this is so,
and whether indeed the supposed substances of a more primi-
tive order would be recognizable by chemical means, is a
question which we are unable to answer. At present we shall
assume that the chemist recognizes the existence of different
substances arising from different relations between the hypo-
thetical matter par excellence and the coordinate essence
which we call energy.

In all this attempt to formulate the essential conditions of
material existence, the tendency of our mind is toward a sim-
plification of our standards of reference, — toward a lessen-
ing of the number of pigeon-holes into which new ideas must
be put. We love to believe that the higher we ascend on the
scale of causation, the smaller becomes the number of co-
ordinate causes. Our experience appears to justify us in this
reasoning, and so, as I have said, we have arranged for our-
selves at that point where our experience appears to stop,
the fiction of these four principles, space, time, matter, and
energy. Let us not flatter ourselves, however, that this is an
achievement of modern physics. The speculations of philos-
ophers long ago led them to the same physical conceptions,
and if Aristotle's elements appear grosser to us, it is because
we have stripped off, as unessential, some of the accessory
qualities with which he had clothed the mathematical skele-
ton. Struggle as we may, we cannot rid our own few prin-
ciples of some quality in common and consequently ulterior:
above all things we give them alike that vague, awesome at-
tribute of existence: essences, let us call them, because they
appear to us to be the ultimate things that exist, according
to our mundane imagination. All that we tell ourselves is,

IDEAS OF PHYSICAL CHEMISTRY 11

that we can ascribe all the phenomena which we see to the
combination of these essential principles, of whose nature
we know nothing, and which are, consequently, infinite to us.
This does not preclude our singling out finite portions of
these, so to speak, and defining them by each other.

We have seen that we are not justified in calling substance
a manifestation of matter free of energy: it is so intimately
connected with certain forces (such as gravitation) which are
convertible into so-called manifestations of pure energy,
that we cannot conceive of it as existing deprived of these,
and yet remaining recognizable. But we may neverthe-
less class all substances together in one general class called
matter.

Thus also, the various modes of energy — heat, motion,
electricity, chemical affinity — are phenomena which we
dare not ascribe to energy alone, for we cannot conceive them
as separated from matter. We can, therefore, speak of their
differentiation also, although we may picture the tran-
scendental energy as one and homogeneous. Indeed, con-
sciously or unconsciously, this distinction is made in the
science of thermodynamics, which proposes to treat energy
in its abstractest form. . . .

In view of these philosophical complications, I propose
that we do not allow ourselves to be hampered by metaphys-
ical notions as to the respective homogeneity of matter and
energy, but that we accept frankly, at the outset, the appear-
ance of substances and forces in various distinct forms.
Physical research will show us that there exist between all
these forms certain relations, about which it is our duty to
procure definite ideas. If the advance of knowledge shall
gratify our love of symmetry, by proving that the correla-
tions of the various forms may be traced to the existence of a
simpler set of relations, of a higher order, well and good ! But

12 MORRIS LOEB

let us not allow our feelings to warp our judgment, or a priori
reasoning to mislead our investigations.

Of the various properties by which we recognize substance,
there are some which are necessary concomitants of the very
existence of matter, — which appear to accompany matter
so faithfully, that no particle can boast of holding much more
than another. Among these we reckon extent, impermeability,
mobility, gravitation, inertia. . . .

Then there are other properties which we do not hesitate
to term accidental; they are so loosely connected with the
substances that we do not recognize the substances as dis-
similar on that account. They might more properly be ap-
plied to the differentiation of energy. Such properties are
position, temperature, electrical or magnetic change. They,
indeed, may appear on one body more than on the other; but
exchange the proportionate quantities in the two bodies, as
well as we may, and yet we shall not be likely to confound one
body with the other. These are all transferable properties,
the one body gaining what the other loses.

There are, however, yet other properties, more or less
concerned with the foregoing, which two bodies may not
possess in like degree, and which it is impossible for one body
to convey to the other. Substances differ in their behavior
toward the same form of energy or toward each other, in
the distribution of their mass in space (specific gravity), in
their effect upon our senses, and upon the animate organism
in general. These properties cannot be transferred from one
body to another; but one substance may modify by its pres-
ence the properties of another. Such are the properties
which really distinguish the different forms of matter, and it
is with these that chemistry has to do.

The indivisible unit for the chemist is to be found in the
homogeneous substance; beyond this he must confess that

IDEAS OF PHYSICAL CHEMISTRY 13

he cannot go. As soon as he has found something in which
he can detect nothing heterogeneous, which he is unable by
any known means to divide, he stops at what he calls the
elementary atom.

You will notice that this is by no means a positive defi-
nition by which we deny to our imagination the right of
subdividing our atom or of dissociating our element. We
merely ask for better proof than that of instinct, before we
allow the inferences that are to be drawn from such a further
subdivision to affect our treatment of the subject. The testi-
mony which we present in favor of the homogeneity of our
ultimate element is purely negative: we have found no hetero-
geneity. For example, we take this piece of rock; to the
geologist, it presents itself as a unit, granite. The lithologist
sees in it a composite mass of quartz, feldspar, and mica,
which again are individuals for his eye. But for the chemist,
feldspar is highly complex: he can isolate from it, silicon,
oxygen, potassium, aluminium, magnesium, iron, and possi-
bly other elements. No means have yet been devised so
subtle as to subdivide these elementary substances.

Recognizing such as our simple substances, we find that
each has certain properties of its own, which serve to dis-
tinguish it from the rest, and which cannot be transferred
from it to one of its fellows. The ancient and mediaeval
alchemists regarded these elements as composites, contain-
ing in different proportions those principles of Aristotle to
which we have already referred. To them, therefore, it
seemed perfectly logical, that by addition or subtraction of
some quality-bearing principle, one metal could be converted
into another. It is only because we have, by carefully con-
ducted experiments, found the metals to be homogeneous,
toward all the agencies which we know, — that we have come
to another conclusion, and ridicule the idea of their mutation.

14 MORRIS LOEB

Their reasoning appeared to them to be as logical as ours is,
when we propose transforming the sap of the pine into the
essence of vanilla, or of converting clay into the true ruby.

As I have said, we recognize upwards of sixty-five elements,
but we rarely see any of these pure. Terrestrial objects must,
then, be made up of combinations of these elements. In
order to study them in the pure state, they must usually be
separated from each other; and they are worthy of very care-
ful study.1 . . .

You are aware of the Periodic Law of Newlands, Lothar
Meyer, and Mendeleeff, which traces such remarkable re-
lations between the various properties of the elementary
substances and the relative masses of their imaginary atoms.
Attempts to connect this law with the idea that the elements
are compounds in a chemical sense are abortive. I believe
that the law can be more readily traced to the relation of the
quantities in which our fundamental ideas of matter, energy,
and space are associated for each element. The atoms of the
elements have undoubtedly different densities. That is to
say, our knowledge of the sizes of the atoms, limited though
it be, does not allow us to suppose that an oxygen atom occu-
pies sixteen times the volume which a hydrogen atom requires,
although this is the ratio of the masses of these two kinds of
atoms. For the same amount of space there seems to be more
matter in the oxygen atom than in the hydrogen atom; we
may assume that similar relations exist in other cases with
regard to energy and matter. For each element we should have
to assume new quantities of matter, space, and energy; and
the ratios of every one of the three with respect to each other
would vary. We might suppose, however, that for a series
of elements the ratio of two of the fundamental quantities

1 The lecture notes on physical chemistry here became fragmentary. The fol-
lowing six pages were taken from two summaries evidently prepared for addresses
on other occasions. [EDITOR.]

IDEAS OF PHYSICAL CHEMISTRY 15

remained fixed, but their ratio toward the third varied; in
such cases we might expect marked similarity in their proper-
ties, as compared with those cases where all the ratios varied.
Such reasoning, carried out more fully, might explain the
peculiarities of the Periodic Law, even though this does not
necessarily imply that no other explanation is possible.

Even if we do not altogether understand the relations
between the elements, our chemical theory concerning the
nature of these elementary substances is very simple. Assum-
ing the elements to exist, each element is represented by one
set of extremely small indivisible atoms, the atoms of the
same element being exactly alike in all respects. They are
independent bodies exerting upon other atoms an attraction
which varies according to their nature. . . .

These atoms are supposed to unite into small clusters that
we call molecules, and consider as the smallest independent
bodies that have the properties of ordinary tangible sub-
stances. They remind us strongly of planetary systems, like
our solar systems, because they execute their own movements
quite independently of the movements of their constituent
atoms. The molecules present comparatively easy problems
to the theorist; their own motions seem to be simple and their
mutual attractions are at least in part those of gravitation.
The so-called "kinetic theory of gases" explains all phenom-
ena of the gaseous state very readily by assuming that
molecules move in straight lines until they hit an obstacle and
are then reflected. If molecules come very close to one an-
other, their relative attraction becomes much greater than
that which corresponds to gravitation. I think it fair to as-
sume that then their more complex chemical attractions
come into play.

Thus our chemical philosophy becomes an attempt to inter-
pret the actions of these imaginary atoms constituting matter

16 MORRIS LOEB

under the play of the various forms of energy which pertain
to them; and these actions must be supposed to take place
in tridimensional space during perceptible time.

Let us turn now to the consideration of energy. We talk
of kinetic energy, or energy performing work, and of poten-
tial energy, or energy which is capable of performing work,
but not yet doing so. In the case of the mechanical energy
of motion, the potential form involves change in time but not
in other obvious ways. It keeps on existing in the shape of
a tendency to move, attraction or the like, while the kinetic
form involves both a change in respect to time and to the
directions of space. We recognize this in the word speed,
or velocity, which expresses the distance traversed in com-
parison with the amount of time consumed. I think this
energy of motion to be the easiest to conceive, and conse-
quently the most natural to imagine as at the bottom of all
phenomena of energy. Certain it is that physicists are finding
more and more reason to believe that all the various forms
of energy are really only manifestations of different sorts of
direct motion.

For example, we find that what we know as heat or light
may be simply interpreted as a manifestation of the motions
of the molecules. If we heat a substance, its molecules may
be supposed to move more rapidly in straight lines and vi-
brate or oscillate more rapidly. The oscillations they are able
to impart to neighboring particles that may be incapacitated
from directly taking up the rectilinear motions. If these mo-
tions or oscillations are very rapid, they affect our sense of
temperature. They may partly belong to the molecule as a
whole, partly to its atoms.

All sorts of molecules may be supposed to receive the straight
motions in equal degree; but each molecule seems to respond
only to certain kinds of oscillations. So we can throw a set

IDEAS OF PHYSICAL CHEMISTRY 17

of bells an equal distance at the same speed; but each bell has
its own rates of vibration, its tones and over-tones. You know
that in light and heat vibrations, the colors of the spectro-
scope are due to the preference which molecules exhibit for
certain rates of vibration. . . .

What now are the forms of energy concerned in causing
chemical action? Until recently the chemist has dealt with
static chemistry, — that is, the science in which the proper-
ties of quiescent substances are discussed, — rather than with
the branch of knowledge which discusses the mechanism of
chemical change. Whenever affinity is treated as a specific
inherent property of the atoms, we naturally adopt the old-
fashioned views first enunciated by Bergmann more than a
century ago, that elements unite according to their specific
affinity for each other. If two substances are presented to a
third which would combine with either of them, it was sup-
posed to take up the one for which it had the greater affinity,
leaving the other uncombined. This doctrine of elective affini-
ties is a comfortable, but unfortunately an incomplete one.
It represents only one side of the question.

If we continue building upon the kinetic theory discussed
above, a more complicated process is to be expected. As a
matter of fact we find that substances act upon each other
not only according to their mutual affinity, but are also
influenced by such conditions as their relative quantities in a
given space, their temperature, etc. To illustrate the former
of these two circumstances, suppose a mixture of equal masses
of A and B, which do not act upon each other, to be pre-
sented to C, with which both can react, but A more readily
than B. A and C will unite, but not to the exclusion of B;
there will be a partition of C between A and B, in which
A, the more active, gets the greater share of C. When, how-
ever, the quantity of B originally present is increased, more of

18 MORRIS LOEB

C will combine with B than would originally combine with it.
This is due to the fact that chemical action is due to exchange
of atoms when molecules meet. In spite of some reluctance
to combine between B and C, the greater number of mole-
cules of B present causes more frequent meetings between
B and C atoms than between A and C atoms. Throughout
chemical reactions it is found to be true that the ultimate
result depends thus upon the relative concentrations of re-
agents quite as much as upon their affinity. This then is a
second aspect of the science of energetics which applies to
chemical action.

Formerly the chemist measured or weighed the substances
which he put together; and then measured and weighed the
ultimate results, wrote an equation and heaved a sigh of
satisfaction at having mastered the mechanism of the reac-
tion. Since the ideas above related have been introduced, we
strive to follow the reaction while it is going on, to detect
the molecules at work. We must often devise special methods
for such a purpose and many difficulties have hitherto seemed
unsurmountable. But when we do obtain such glimpses, we
become more and more convinced of the fewness and sim-
plicity of the fundamental ideas which we require for a basis
of the science.

In any simple reaction, there is a perceptible interval of
time between the mixture of the ingredients and the com-
pletion of the ultimate result. Why is this? Because a
measurable interval elapses before all the molecular changes
have taken place. This will depend, as pointed out above,
first upon the readiness with which the exchange takes place
(a question of affinity), secondly upon the frequency of meet-
ing of the reacting molecules. Molecules will meet more
freely if there are more of them in a given space, and if they
move faster through added energy; and colliding molecules of

IDEAS OF PHYSICAL CHEMISTRY 19

the two reacting substances will combine more frequently,
the greater their mutual affinities. This relation of chemical
change to time is one of the most important aspects of modern
physical chemistry.1

In recent years it has become possible to produce an in-
tense cold, and it has been observed in the laboratories of Pro-
fessor Dewar and others, that as the temperature decreases,
the speed of reaction also decreases. Furthermore, it has long
been known that matter usually contracts, that is to say,
occupies less space, as it grows colder. At a temperature
minus 273° centigrade, all heat energy ceases, all chemical
reactions become exceedingly slow, and all volume approaches
as near as possible to nothing without the actual disappear-
ance of substance. It is fair to assume that at such an abso-
lute zero various other properties by means of which we dif-
ferentiate substances would disappear, and this, too, is veri-
fied by recent observations. Nevertheless, all substances
by no means become identical at this point. Because heat is
a form of energy, and cold is only the absence of that form
of energy, we have here only another aspect of the ever-re-
curring effect of the changing relation of matter to energy
in producing the phenomena of our actual world.

In summing up the outcome of our work in this lecture,
it is clear that we have built a sort of platform, floating upon
a sea of uncertainty, but of sufficient strength and stability
to permit the erection of a more solid edifice of physico-chemi-
cal theory. Let us cast another glance at the planks. We have
the four fundamental ideas, matter, energy, space and time
- which occur in everything superposed upon one another
but not in a constant quantitative ratio; these abstract es-

1 An experiment demonstrating the effect of concentration and temperature
upon the speed of reaction is given at the end of the Appendix to this volume.
[Editor.]

20 MORRIS LOEB

sences cooperate in the manifestation of chemical substances,
of kinetic energy of motion, and of potential energy of posi-
tion. I think that you will agree with me that although we
may not be generally aware of it, these four fundamental
conceptions work together in our minds and our senses in
producing all our perceptions of the chemical phenomena of
nature.

OSMOTIC PRESSURE AND THE DETERMINA-
TION OF MOLECULAR WEIGHTS1

WITHIN recent years it has become more and more appar-
ent that an intimate connection exists between the stoichio-
metrical composition of a solution and its physical behavior.
While earlier efforts towards proving this assumption were
unsuccessful, chiefly because the experimental material was
almost wholly confined to aqueous solutions of salts, which
offer peculiar obstacles to such an investigation, F. Raoult's 2
patient researches upon organic substances in more varied
solutions have enabled him to formulate accurately the long-
expected laws, and to put the chemical world under lasting
obligation for new methods for determining molecular
weights under very favorable conditions. Raoult's law would
read, in its most general form : In dilute solutions the depres-
sions of the vapor tension and of the freezing-point of the
solvent vary directly with the ratio between the numbers of
molecules of solvent and of substance dissolved in the mix-
ture. Provided there be no chemical action involved in the
process of solution, this relation is entirely independent of
the nature of the substances.

Within the ordinary range of conditions, the freezing-point
of a pure liquid is constant; according to Raoult's law, every
molecule of foreign matter occasions the same constant de-
pression. Every liquid, however, has its own constant coeffi-
cient of depression, which may be found by determining the
depression caused by the presence of one molecule of any
substance in one hundred molecules of the liquid.

1 A brief review of preceding work published in the American Chemical Journal,
12, 130 (1890).

2 Campt. rend. 87, 167 (1878); 95, 1030 (1882).

22 MORRIS LOEB

The vapor tension of a liquid is not constant within the
range of ordinary experimentation, since it is a complex func-
tion of the temperature and of the nature of the substance.
But Raoult has shown that its depression shows a relation
to percentage of foreign molecules which is independent of
temperature, provided he expresses the depression, not in
absolute measure, but as a fraction of the tension of the pure
solvent at the same temperature. Then the molecular de-
pression, i.e., the product of the molecular weight of the sub-
stance dissolved into the relative depression of a one per
cent solution, becomes a definite constant for any substances
which that particular liquid may dissolve. It is noticeable
that this constant's numerical value always approaches very
nearly -j^ of the molecular weight of the solvent. The con-
stant is therefore likewise independent of the nature of the
solvent; one may generalize for all solutions, that the ten-
sion of the pure solvent is to the actual depression as is the
number of molecules of solvent to the number of molecules of
substance dissolved.

Laws as simple as these point to conditions, in solutions,
very like those existing in the gaseous state. How great this
analogy is has been shown in the well-matured papers of J. H.
van 't Hoff 1 on osmotic pressure. Osmotic pressure is the
name given by van 't Hoff to the force with which a liquid
will enter into a cell containing the solution of some sub-
stance in that liquid through walls which are pervious to the
solvent alone. Pfeffer2 has shown that when such a cell is
put into a vessel containing the pure solvent, the latter will
enter the cell, increasing the bulk of the solution within, until
this tendency is counterbalanced by the difference of level
in the two vessels or some other pressure. The pressure

' Z. physik. Chem. 1, 481 (1887).

* Monograph, Osmotische Untersuchungen. Leipzig, 1877.

OSMOTIC PRESSURE 23

required to counterbalance this tendency toward endosmose
is always the same for the same concentration of the solu-
tion, and for different concentrations is found to be propor-
tionate to the number of molecules dissolved in the unit
volume. Whether this osmotic pressure be due to the motions
of the dissolved molecules or to the attraction of some other
sort which they exert upon the solvent, it is evident that
the effect must depend upon the number of molecules per
unit volume only when the molecules of the dissolved body
are free to act independently of each other, as do the mole-
cules of a gas. What the real kinetic energy of the molecules
in such a solution is, we do not decide by drawing this con-
clusion. Even if it be as great as in a gas, the great resist-
ance which a solvent opposes to diffusion shows that there
is a force which greatly diminishes the external effect of this
kinetic energy; it can never, therefore, have occurred to
van 't Hoff to claim that osmotic pressure is to be measured
externally in the same absolute unit as gaseous pressure.
But this opinion seems to have gained a foothold, so that
the kinetic treatment of the subject is combated by M.
Pupin,1 on the ground that the kinetic energy of the mole-
cules in a solution ought to burst the containing vessel when
it was concentrated to what would correspond, in the gaseous
state, to a volume under the pressure of many atmospheres.
For this reason he demands that osmotic pressure should be
treated as a static phenomenon. To the writer, Dr. Pupin
appears to confound molar and molecular kinetics. Because
the mass as a whole is in equilibrium and at rest, it does not
follow that the molecules must be; in fact very few physicists
would care to call any force static in the sense that it was
not occasioned by kinetic forces held in equilibrium for the
moment.

1 Dissertation, Der osmotische Druck, etc., University of Berlin, 1889.

24 MORRIS LOEB

That the vessel is not exploded by the pressure of the
molecules, as Dr. Pupin demands, is due to the same force
of solution which prevents their evaporating at the free sur-
face. How great this force can become we may guess from the
enormous condensation taking place in the absorption of
gases by liquids; that the force is a kinetic one is shown by
its being a function of temperature, a purely kinetic phenom-
enon. Bredig1 has recently endeavored to show how this
force can be made to diminish the external effect of the
kinetic energy of the molecules of dissolved substance in
such a manner that there is still freedom of action within the
mass; and upon this line of reasoning we must depend for a
final explanation of the phenomena.

For van 't Hoff it was, however, sufficient that an osmotic
pressure does exist which is dependent upon the kinetic
energy of the molecules. By simple application of the
method of Carnot's cycle, he shows that the osmotic pressure
must be proportional to the absolute temperature, and that,
for solutions of gases, it corresponds precisely to the tension
of the gas in the solution. A natural inference from all this
is that Boyle's, Gay-Lussac's, Henry's, and Avogadro's laws
find their counterparts in the laws governing osmotic pres-
sure.

Suppose now solutions of two different substances in the
same solvent to possess the same tension for the vapor of
the latter; it is necessary that they shall also have the same
osmotic pressure. For suppose them separated by a wall
which is permeable to the solvent alone, but with their free
surfaces in communication through the atmosphere. The
vapor tension of both being the same, a little of the solvent
might distill from one solution to the other without the per-
formance of any work; but if at the same time their osmotic
1 Z. phydk. Chem. 4, 444 (1889).

OSMOTIC PRESSURE 25

pressure were different, work would be performed by the re-
transfer of the same quantity of solvent through the mem-
branous wall; this would mean a continuous process in an
isolated system, attended by gain or loss of energy. As this
is impossible, equal vapor tension means equal osmotic pres-
sure, and vice versa. Consequently the same number of
molecules always produce the same depression of vapor
tension in a solvent. Exactly the same sort of reasoning
would show that solutions having the same freezing-point
have like osmotic pressures. Both of these laws are identical
with those found empirically by Raoult. Thermodynamic
reasoning further shows that the molecular depression of
vapor tension is indeed one hundredth of the molecular weight
of the solvent, while the depression of the freezing-point

depends more directly upon the nature of the solvent, being

TZ
a function of its latent heat of liquefaction: £=0.02— » where

T is the absolute temperature of congelation of the pure sol-
vent, W is the latent heat per kilogram, and t is the molec-
ular depression.

These are the main results of van 't Hoff 's deductions, as
far as molecular weight determinations are concerned. They
enable us to employ for this purpose, with perfect confidence,
observations upon the phenomena of evaporation, freezing,
and osmose.

The direct measurement of osmotic pressure, as was done
by Pfeffer, is difficult and not universally feasible. On the
other hand, de Vries has shown how to compare such pres-
sures by means of plant cells.1 It is found that the living pro-

1 Pringsheim's Jahrbucher fur Wissenschaftl. Botanik, 14, 4. See also Z. physik.
Chem. 2,414 (1888). Bonders and Hamburger have shown that the same phenom-
ena can be studied in the behavior of blood-corpuscles; Archiv. fiir Anatomic und
Physiologic, Physiolog. Abth. 1886, 476, also Hamburger, Maanbl. Nat. Wetensch.
1889, 63.

26 MORRIS LOEB

toplasm of such cells, placed in a solution whose solvent only
can penetrate the membrane, will yield water to the solution
if the latter be concentrated, while it will take it up again if
the solution be diluted. The protoplasm will therefore re-
cede from the walls of its cell, or again approach it, and this
expansion or contraction can be observed with the micro-
scope. By systematic dilution, a point may be determined
for every substance where it is isotonic with another, i.e., will
neither expand nor contract a protoplasm which had come
to rest in the other. Interesting as this method is, and ca-
pable of yielding good results in the hands of a skillful micro-
scopist, it is hardly useful in the chemical laboratory, where,
aside from lack of familiarity with microscopic work, the
investigator would be hampered by the exclusion of all
substances which will kill plant life.

The freezing-point method has recently been reviewed in
this magazine; it therefore only remains for the writer to
express his view of its scope. While originally only those few
liquids were used as solvents whose freezing-points approached
that of water, recent investigators have successfully em-
ployed substances like paraffine and the more fusible metals
as the solvent; there are, therefore, few substances which are
not amenable to the method. But the following errors should
be avoided: the use of thermometers not sufficiently sensi-
tive to admit of observations at high dilutions; contenting
one's self with observations within too limited a range of con-
centration to exclude a chance of overlooking abnormal be-
havior at some point; allowing too great a change of concen-
tration to occur through the separation of the solvent in the
solid state; using solvents which have a chemical effect upon
the substance under investigation. Substances dissociate in
one liquid which remain in complexer molecules in another.
Chemists, in applying Raoult's methods, must remember

OSMOTIC PRESSURE 37

that all electrolytes behave abnormally in aqueous solutions*
and that the presence of hydrates may affect the result.

The method of determining the molecular weight from the
vapor tension of the solution is not yet applied so generally;
but its scope is even greater, because the range of solvents and
of temperatures is so largely increased. Raoult and Planck1
have shown independently of each other that the formula
for the molecular weight of the dissolved substance is

where M 0 is the molecular weight of the solvent, p the per-
centage of substance in 100 grams of solvent, / and /' the
tensions of the pure solvent and the solution respectively.

Raoult measures / and /' by the heights of the mercury in
eudiometers containing the liquids. A knowledge of the true
value of p depends upon the determination of /', as part of
the solvent leaves the solution as vapor under that tension;
therefore an error in determining /' affects the result three
times in the same direction. The method is less exact and
more inconvenient than that of determining the freezing-
point.

A dynamic way, applied under Ostwald's direction by
Walker,2 is very much easier: determine the amount of water
which different solutions will yield to the same amount of air.
The measurements are made on the balance, and the appa-
ratus consists of one set of bulbs to contain the solution,
another to hold an absorbent for water, and an aspirator.
The method has been generalized by Will and Bredig3 for
other solvents.

Lowering the tension means raising the point of ebullition

1 Z. physik. Chem. 2, 353 seq., 405 seq. (1888).

2 Z. physik. Chem. 2, 602 (1888).
8 Berichte, 21, 1084 (1889).

28 MORRIS LOEB

for normal pressure, and the boiling-point is, of course,
capable of most exact determination. The method has been
elaborated by Beckmann,1 while the reader will remember
a recent paper by Wiley on this subject, which does not, how-
ever, give sufficient details, as Beckmann's paper had al-
ready been announced.

The latter 's apparatus consists of a vessel of about 100 cc.
capacity, having a rounded bottom and three necks. Of these,
the central one connects with a Soxhlet condenser, the second
carries a Beckmann thermometer, whose bulb is completely
submerged, and the third neck serves for the introduction of
the substance.

Steady boiling is assured by filling the vessel to a certain
height with beads or garnets, and by sealing platinum wires
into the bottom to promote conduction. The pure solvent is
first raised to the boiling-point, its temperature noted, and
the weighed substance is thereupon introduced. As soon as
the thermometer has become constant, the rise is noted; a
fresh quantity of substance may then be introduced, and
the observation repeated. The formula for the molecular
elevation of the boiling-point is precisely like that found by
van 't Hoff for the freezing-point,

0.02 T2
t = >

W

with the exception that here T means the boiling-point of the
pure liquid and W its heat of vaporization. The constant t
being found by calculation or experiment, whenever we deter-
mine that for p grams of substance to 100 grams of solvent
there is an elevation e, the molecular weight of the sub-
stance being M ,

M^
e

1 Z. physik. Chem. t, 532 (1880).

OSMOTIC PRESSURE 29

The experimental data to show the value of this method
have not been published as yet, but it appears to be des-
tined to play as great a part as does the freezing-point
method introduced in its most convenient form by the same
chemist.

ELECTROLYTIC DISSOCIATION: A REVIEW OP
THE HYPOTHESIS OP SVANTE ARRHENIUS l

IN 1857, almost simultaneously, Williamson and Clausius
put forward the hypothesis that, in the fluid state at least, the
molecules of compounds are not stable, in the sense that they
are persisting aggregations of the identical molecules which
originally united to form them; on the contrary, it was as-
sumed that these molecules in so far resemble living organ-
isms that, while the external appearance remains unchanged,
the constituents are constantly being cast off and replaced
by new ones of the same kind, so that there must always be a
few molecules in a state of dissociation. This hypothesis has
been favorably regarded as an explanation of the possibility
of the coexistence of two opposing reactions, like those of
etherification and saponification, where it is left to the chance
encounter of molecules to occasion the existence of water and
ether, or of alcohol and acid; it has likewise been regarded
as a plausible explanation of the readiness with which an
electrolyte will obey the influence of currents so feeble that
their energy should not suffice to decompose a single mole-
cule whose atoms were held together by their full chemical
attraction. But when, six years ago, the attempt was made
by Arrhenius to give a quantitative expression to the hypoth-
esis and to apply it to the explanation of all the anomalies ob-
served in the physical behavior of solutions, much latent
hostility was called forth, and a general discussion was aroused,
which has continued until the present time. It appears, how-
ever, to the reviewer that a point has now been reached
where the burden of proof should rest upon the opponents

1 Reprinted from Am. Chem. Journ. 12, 506 (1890).

ELECTROLYTIC DISSOCIATION 31

rather than upon the supporters of the hypothesis. An analy-
sis of this discussion, set forth in proper order, might prove
both lengthy and confusing, and I therefore relegate a chrono-
logical list of the original papers to the end of this review and
confine myself to a brief exposition of the hypothesis as it
stands at present, and of the chief objections which have
been raised to it.

The fundamental idea is this: In electrical conductors of
the second class electricity can be transported only by elec-
trically "active" molecules, i.e., those in which the electro-
static charges are not neutralized within the molecule; the
ions are able to receive and transport charges, positive and
negative respectively, as long as they are separated, but not
when they are firmly knit into a neutral molecule. It follows
that there can be no conduction without a preexistent partial
dissociation of the molecules, which may be occasioned either
by heat or more generally by the presence of a foreign body,
such as water. It is, for instance, a well-known fact that some
of the best conductors, like the strong acids, become insula-
tors when freed from the last traces of water, while water
itself is classed among the poorest conductors when free from
impurities. The mechanism by which water, par excellence,
should produce electrolytic dissociation, while alcohol and
other solvents do not, has yet to be explained; it does seem
strange that such an effect should be produced without a cor-
responding dissociation of the water, an idea which Arrhen-
ius rejects or admits only to a minimal extent. However
that may be, electrolytic dissociation is assumed to be a phe-
nomenon closely corresponding to gaseous dissociation and
obedient to laws expressed by the same thermodynamic for-
mulae, with this difference, that "osmotic" pressure must
replace gas pressure. Consequently, dissociation must be
increased by dilution (increase of volume) and by heat; but

32 MORRIS LOEB

for different substances the corresponding coefficients may
differ.

1. The first application of this hypothesis affects Kohl-
rausch's law of conduction;1 the conducting power of an elec-
trolyte is no longer the sum of the velocities of all the ions,
but of that proportion which are free to move. Only for
extreme dilutions do we find a rigorous adherence to the
equation \=u+v, which becomes in less dilute solutions
\ = a(u +v) (I), where a expresses the "coefficient of ac-
tivity," or that proportion of the whole number of mole-
cules which is dissociated. Experiments having given very
reliable results for u and v in the case of quite a number of
ions, and X being known for a large number of compounds
at various degrees of concentration, the respective values of
a are readily obtained.

2. The number of molecules in the solution is increased by
the dissociation. If each molecule is dissociated into k con-
stituent ions, and n\ molecules are thus broken up, while n
remain associated, the osmotic pressure must correspond to
the presence of n+krii molecules, instead of n+ni. We shall
have for the relation of the true osmotic pressure to that
calculated upon the assumption that the molecules remain

intact, i

The definition of the coefficient of activity has introduced
the value a= — — > whence

-l)a (II)

This explains the fact, alluded to in a recent review, that
the molecular weight of an electrolyte, as determined by any
of the "osmotic" methods, must be found smaller than

1 Compare Am. Chem. Journ. 11, 116 (1889).

ELECTROLYTIC DISSOCIATION 33

theory would require. The coefficient i has been determined
for many electrolytes, both by the freezing-point method and
de Vries's and Hamburger's isotonism methods, and has in
almost every case been found to agree astonishingly well
with the corresponding value obtained from equation II,
after calculating a by equation I. The few exceptions are
found for salts which behave anomalously in other respects,
andfcan be explained by making further assumptions which
need not be discussed here.

3. If k =2, that is if the electrolyte consists of but two
ions, as in the case of monobasic acids and their salts with
monovalent metals, the dissociation ought to obey the law
which has been found to hold for gaseous dissociation where

one molecule breaks up into two constituents, — = const.,

Pi

p now referring to the osmotic pressure of the integral mole-
cules and pi to that of either set of ions of the dissociated
ones. The osmotic pressure depends upon the number of
molecules in the unit volume of solution. Therefore, if we

call the volume of the solution V9 p=— , p\=— l, and — =

V V n\

const.

If the dissociation were complete, a result reached at in-
finite dilution, the molecular conductivity would reach a
maximum value /m«>, but at the finite dilution F, it has a
smaller value pv9 which is a measure of the number of dis-
sociated molecules in the total. We can substitute in the

last equation the value n\=— » and n=l-^-£» and obtain

In this form the ratio has been examined by Ostwald,
and has been found to remain practically constant for any

34 MORRIS LOEB

one substance from one-fourth normal solution up to the
very highest dilution amenable to experiment. For different
acids, this constant assumes different values which have
proved to be closely connected with the chemical activity of

these acids. Putting m=^ and K=-, we can note for refer-

fr C

ence the equation to which Ostwald now reduces his results :

— ^— =K (III)
(l-m)F

4. If the solution of an electrolyte really contains free
ions, how is it that this does not at once become apparent,
either by the decomposition of water, or by some physical
heterogeneity of the system? The answer lies in the further
definition that these free ions bear equal and opposite electro-
static charges, which do not permit any local preponderance
of one sort of ions over another, as this would mean a local
accumulation of electricity in a system which is in equi-
librium. Consequently — although the ions travel with dif-
ferent velocities — if they are traveling in the same direction
as in diffusion, the attraction of their electrostatic charges
compels them to accommodate their rates one to another, so
that the slower ion is accelerated while the faster is retarded;
the rate of diffusion of the salt is therefore intermediate be-
tween the velocities of the two ions. These conditions have
received a rigorous mathematical formulation, and the close
agreement between the theoretical and experimental results
affords a beautiful confirmation of the fundamental hypoth-
esis. (Nernst.)

5. Any cause, on the other hand, which produces a rela-
tive dislocation of the positive and negative ions must occa-
sion electrical heterogeneity, showing itself by differences
of potential at different points. Upon this idea a plausible

ELECTROLYTIC DISSOCIATION 35

"osmotic" theory of voltaic electricity has been based and
substantiated by experiment. (Nernst.)

6. Conversely, any difference of electrical potential in the
solution must produce a motion of the ions. Here we have
the Clausius hypothesis of electrolysis. The introduction of
electrodes disturbs the equilibrium of the solution, the posi-
tive ion moves to the cathode, where it gives up its charge,
while the negative ion does the same at the cathode. It is
only when the ions are relieved of their charges that they are
capable of attacking the metal of the electrodes, or of de-
composing water, causing the well-known secondary effects;
charged, and in the paralyzing presence of an opposite charge,
they are supposed to be incapable of doing this. In this
connection may be cited an experiment which appears in-
comprehensible unless free ions are assumed to exist in the
solution. Dilute sulphuric acid, contained in a flask whose
exterior was coated with tin foil, was connected by a wick
with aLippmann electrometer; upon giving a positive charge
to the exterior of the flask the electrometer indicated the
presence of positive electricity, and some bubbles of hydro-
gen were evolved near it. Consequently, the flask, being a
modified Leyden jar, negative ions (SO4) had collected on the
interior, while the corresponding hydrogen had been driven
over toward the electrometer.

7. Properties like density, refractive power, capillarity
and viscosity of saline solutions, whose numerical values ap-
pear to depend upon the sum of two factors characteristic of
the acid and of the metal, should show this additive nature
best where the salts are most dissociated; this appears to be
the case.

8. We have now to consider the chemical side of the
hypothesis, and we are met by the startling assertion that
those acids show the greatest degree of dissociation which we

36 MORRIS LOEB

consider the strongest. Indeed, according to Arrhenius,
chemical activity depends upon the degree of electrolytic dis-
sociation, only the dissociated molecules being capable of
entering into reaction. A fundamental difference is hereby
inferred to exist between reactions among electrolytes and
reactions introducing only non-electrolytes, or, to recall
antiquated notions, between reactions which involve sub-
stances of the water and hydrochloric acid types, and those
involving merely the hydrogen and ammonia types. Valid
objections raised to this distinction would upset the theory
from the chemist's standpoint: examples in favor of the dis-
tinction have been adduced, such as the fact that the char-
acteristic halogen reaction with silver nitrate is only shown
by such compounds in which the halogen can be supposed to
exist as a free ion, while with those which contain the halo-
gen within the radicle, like trichloracetic acid, the reaction
fails. Considering by themselves the reactions between
electrolytes, it is noticeable that the presence of water or
another solvent appears to be necessary (cf . the passivity of
absolutely dry gases). The law of Guldberg and Waage must
be modified in so far that the speed of reaction is not a func-
tion of the total masses of the electrolytes in solution, but
of the masses of dissociated ions : van 't Hoff has introduced
the coefficient i (isotonic coefficient) successfully enough into
these considerations, and i has already been shown to be a
function of a (II). In the acceleration or retardation of
etherification and saponification, the acids and bases must
act proportionately to their stages of dissociation, so that
Ostwald's old affinity-coefficients must correspond with the
values of k in equation III, which is also found to be true;
for the same reason the effectiveness of weaker acids (non-
dissociated) increases more rapidly for additional dilution
than does that of stronger acids which are much nearer their

ELECTROLYTIC DISSOCIATION 37

limit. The evidence to be obtained from the study of the
kinetics of chemical reaction all appears to favor the theory.
9. New ideas are introduced with regard to chemical equi-
librium. The laws of dissociation, where gases are concerned,
lead to the well-established postulate that dissociation shall
be greatest where the atmosphere contains no excess of either
of the constituents into which the molecule will break up; dis-
sociation is unaffected by the presence of any other indiffer-
ent substances. By analogy, if a solution already contains a
number of free ions of a particular sort, any substance con-
sisting in part of this same sort of ions will not dissociate as
fully as in pure water. Consequently an acid will be weak-
ened by the presence of one of its neutral salts, but the effect
will be much more perceptible for a weak acid than for a
strong one. This has been verified by Arrhenius. Comparing
on the other hand, acids which have the positive ion H in
common, a mixture of the two must affect their respective
degrees of dissociation, unless before mixing the H had the
same osmotic partial pressure in both solutions. This means
that there shall be the same degree of dissociation in the
two solutions, that they shall be "isohydric." Under such
conditions, if ra parts of one solution having the conductivity
a be mixed with n parts of the other having the conductivity
6, the resulting solution will conduct as if each electrolyte
were conducting independently and unchanged. Its conductiv-
ity is - — , no matter what the relative values of m and
m+n

n are. Furthermore, if two solutions are "isohydric" with a
third, they must be isohydrous with each other. These two
consequences have been substantiated by the examination
of the conductivity of mixtures of "isohydric" solutions of
acids with one another and with those of their respective
neutral salts, of neutral salts with one another and with the

38 MORRIS LOEB

solutions of their respective bases, and finally of the bases
with one another.

But if solutions are mixed together which are not "iso-
hydric," the resultant conductivity will be greater than

ma , if calculation shows that the stronger acid is thereby
m+n

partially reassociated and the weaker partially dissociated,
while it will be less than the normal if the stronger acid is
being dissociated and the weaker reassociated. This depends
upon the fact that the dissociation of the same number of
molecules produces a relatively greater effect when the acid
is farther from the limit of dissociation which all approach
asymptotically. In keeping with these facts is Nernst's ob-
servation that the solubility of a salt is decreased by the pres-
ence of compounds having a common ion with it; thus the
solubility of silver acetate is equally affected by the pres-
ence of silver nitrate and sodium acetate.

10. The theory of "isohydric" solutions leads up to the
important point of the neutralization of acids by bases. In
the first place, salts in dilute solutions are no longer con-
sidered to be the product of a reaction like the following : —

KOH+HC1 =KC1+HOH.

Where there is perfect dissociation, at extreme dilutions,
the reaction is represented thus : —

K+OH+Cl+H=K-fCl+HOH.

At greater concentrations this is accompanied by a certain
reassociation of K-j-Cl and a dissociation K, OH and H, Cl,
but K+C1 is supposed to be very small in all cases, as the
dissociation of salts proves to be relatively very great. Neu-
tralization would therefore practically mean a formation of
water from H and OH, and salts as such would only exist in
concentrated solutions or as a combination of a very weak
acid with a very weak base. A result of this would be that

ELECTROLYTIC DISSOCIATION 39

the heat of neutralization in dilute solutions should be the
same for all sorts of strong acids and bases, and should, in
fact, equal that produced by the reaction H+OH, a very
familiar fact. Mixtures of such salts should not be accom-
panied by a heat effect, which explains the phenomenon of
thermo-neutrality. But a weak base or a weak acid introduces
the positive or negative heat of dissociation pertaining to it;
consequently the thermal effect of neutralization must vary
from that of H+OH, but this variation must decrease with
the increase of temperature. If a stronger and a weaker acid
are together mixed with a base, it is only the weaker anion which
really unites with the metal to a limited extent, while the
stronger anion keeps the relatively greater amount of metal
in electrolytic dissociation, their neutralization being charac-
terized by the union of their former conjugates H+OH. It is
noticeable that electrolytic dissociation is to be sharply
separated from the hydrolysis of sugars and of very weak
salts like ammonium acetate, in which the reaction belongs
rather to the class of non-electrolytes, although electro-
lytes are involved.

A final point with regard to chemical equilibrium is this,
that when equilibrium has been reached in a solution con-
taining a number of electrolytes, each one of these is in a
state of dissociation, which depends upon the equilibrium
of osmotic pressure between the non-dissociated molecules
and all the free ions of the kinds which compose it. A dis-
tribution of metals and acids as it is usually assumed in older
views is therefore rendered out of question, because a free
ion belongs neither to one compound nor to another, it
merely counterbalances that free ion of opposite charge near-
est which it happens for the moment to be.

Having sketched Arrhenius' hypothesis, with some of its
logical consequences, the task of judging it must be left to

40 MORRIS LOEB

those readers who will compare the mass of experimental
material and will convince themselves of the simple relations
which the various phenomena appear to bear toward each
other. As far as this test is concerned, the hypothesis will be
found to fulfill its purpose. Shall it therefore be accepted?

The objections which have been raised are twofold, phys-
ical and chemical. Oliver J. Lodge concedes the inge-
nuity and physical "orthodoxy" of the treatment, and it
might appear that his criticisms to the earlier papers have
been largely obviated by the further development of the
theory; indeed they apply chiefly to points which I have
omitted as no longer seeming essential to the theory, such as
relations between the viscosity and the friction which a
solvent opposes to the motion of the ions. But he appears
mainly to object to the neglect of conduction by the solvent,
which he believes would explain the rate of transference
of the ions, without the assumption of unequal velocities of
negative and positive ions. It is doubtful whether such an
explanation would also elucidate the troublesome diffu-
sion phenomena as well as does "dissociation" in the hands
of Nernst. E. Wiedemann thinks that hydrates are the cause
of better conduction, and explains osmotic anomalies by the
assumption of a polymerization of the solvent. Aside from
Planck's proof, on thermodynamic grounds, that such poly-
merization would not affect the vapor tension phenomenon
in this way, in very dilute solutions, Ostwald pertinently
asks why the electrolyte need cause a polymerization which
no non-electrolyte does.

The objections from a chemical standpoint have been
chiefly raised by Henry E. Armstrong, and are not all co-
gent. The following appear to be the most important at
the present time: —

1. Anhydrous hydrochloric acid and pure water do not

ELECTROLYTIC DISSOCIATION 41

conduct, while fused silver iodide does, which is an anomaly.
Arrhenius finds an explanation in the dissociation of silver
iodide by heat.

2. Hydrochloric, hydrobromic and hydriodic acids differ
markedly in stability, but they are all assigned the same
dissociation ratio. This is evidently a case of misapprehen-
sion, as the instability lies in the negative ion itself, and not
in the compound.

3. Why does not alcohol dissociate electrolytes as well as
water, and why does not water conduct?

4. According to Ostwald's measurements, phenylpropionic,
cinnamic, and phenylpropiolic acids range in the order of
their conducting power, —

C6H5.C.C.COOH>CftH5.CH.CH.COOH>CflH5.CH2.CH2.COOH.
Therefore that acid is most dissociated which can least spare
its hydrogen.

This argument illustrates the necessity of keeping the
types of reactions apart. Nothing appears to justify his as-
sumption that the carboxyl group should be affected in this
way by what happens in a neighboring group, where hydro-
gen plays an entirely different role.

The main opposition to the dissociation hypothesis is to
be found in a rival hypothesis which has found advocates
in Mendeleeff, Armstrong, Pickering, Crompton, Bonty and
E. Wiedemann, — the"hydration" hypothesis connected with
the "residual affinity" idea. Bonty holds that electrolytes are
of two classes, those in which both ions show equal rates of
transference, and the "abnormal" ones, in which this is not
the case. All abnormal salts are said to be capable of form-
ing hydrates and do so. The law of equivalent ratio holds
absolutely in so few cases that these considerations may
be dismissed, in view of the more powerful ideas of Kohl-
rausch. E. Wiedemann argues from the change of color of

42 MORRIS LOEB

salts of nickel, copper, cobalt, etc., upon dilution and heating,
effects which Arrhenius ascribes to a difference in color be-
tween the free ion and the compound. Armstrong and
Pickering present the "residual affinity" theory with much
vigor. The atomic valences are not assumed to be whole
numbers, so that it rarely happens that the positive and
negative valences in a compound just balance. Consequently,
a small residual affinity remains to each molecule, by virtue
of which larger aggregations are formed, molecular com-
pounds, either among the molecules of the same sort or with
the molecules of the solvent. Armstrong's valences represent
the old Berzelian negative and positive electricities, which
cause their respective atoms to tend to opposite electrodes
during the passage of the current, the atoms being set free
by the complexes "straining" at each other as they pass
each other. The idea of unequal electrical charges appears
incompatible with Faraday's law that the current produces
the same effect in all electrolytes. Pickering bases his opposi-
tion upon more modern ideas, separating affinity from elec-
tric charges, and sees in the phenomena of electrolysis and
dilution effects of the dissociation and formation of various
hydrates. The basis for this lies in the observations by Men-
deleeff, Pickering, and Crompton, that various properties of
acids and salts, such as conductivity, density, the heat of
solution, when plotted as ordinates, with the percentage
composition of the solution as abscissas, do not present reg-
ular curves. A study of their first or second differentials
would appear to reveal the presence of points of abrupt
change, and these points are supposed to represent definite
chemical compounds. It does not appear that Arrhenius has
entirely invalidated the proofs of the existence of such com-
pounds, and there is no doubt that they present a very
awkward obstacle to his theory, which he has still to sur-

ELECTROLYTIC DISSOCIATION 43

mount. On the other hand, Pickering's explanations of the
phenomena of freezing are extremely complex, and I am not
aware of any positive attempt to explain facts like diffusion
upon them. The thermo-chemical phenomena might be
fairly explained by Pickering's reasoning.

LITERATURE

1883. S. Arrhenius, Sur la conductibilite galvanique des Electrolytes.
Bihang til Kong. Vet. Ak. Vorh. 1884, Stockholm.

1884. Theorie chimique des Electrolytes.

Van't Hoff, Etudes de dynamique chimique. Amsterdam.

1884. Bonty, Sur la conductibilite, etc., Journ. de Physique (2) 3, 325,
333.

1885. Report of the British Association Committee on Electrolysis,
British Association Report, pp. 723-772.

Pickering, Proc. Chem. Soc. 1, p. 122.

1886. H. E. Armstrong, President's Address, Section C of British
Association of 1885, in Proc. Royal Soc. 40, 268.

Report of Electrolysis Committee for 1886, British Association Re-
port, pp. 308-389, containing criticisms and replies by Lodge, Kohlrausch,
Arrhenius, Bonty, as well as abstracts of papers appearing elsewhere.

1887. Sv. Arrhenius, Einfluss der Neutralsalze auf Verseifungsgeschwind-
igkeit, Zeit. physik. Chem. 1, 110. Innere Reibung verdiinnter wdssriger
Losungen, ibid. 285. Theorie der isohydrischen Losungen, Wied. Ann.
Phys. Chem. 30, 54.

S. IT. Pickering, The Influence of Temperature on the Heat of Dissolution
of Salts, Journ. Chem. Soc. 51, p. 290.

Mendeleeff , Specifisches Gewicht der Schwefelsdurelosungen, Zeit.-physik.
Chem. 1, 273.

Bonty, Sur la conductibilite, etc., Journ. de Physique (2) 6, p. 6.

Van 't Hoff, Ueber osmotischen Druck, Zeit. physik. Chem. 1, 500.

1888. British Association Report of Electrolysis Committee, by O. J.
Lodge, p. 351. Answers, by H. E. Armstrong and S. Arrhenius.

Ostwald, Zur Theorie der Elektrolyte, Zeit. physik. Chem. 2, 36, 270.

Planck, Ueber Gleichgevrichtszustande, etc., Wied. Ann. Phys. Chem. 34,
149.

E. Wiedemann, Ueber die Hypothese der Dissociation, etc., Zeit. physik.
Chem. 2, 241.

Ostwald, Reply, ibid. 243.

Planck, Reply to Wiedemann, ibid. 343.

Arrhenius, Theorie der isohydrischen Losungen, ibid. 284. Gefrierpunkte
verdiinnter wdssriger Losungen, ibid. 491.

de Vries, Osmotische Versuche, ibid. 415.

Nernst, Zur Kinetik der Losungen, ibid. 613.

44 MORRIS LOEB

Van H Hoff and Reicher, Ueber die Dissociationstheorie, etc., ibid. 781.
Pickering, Thermochemical Investigations, etc., Journ. Chem. Soc. 63, 865.

1889. Pickering, Nature of Solutions, etc., Proc. Chem. Soc. 57, 92
(1888-89); Journ. Chem. Soc. Trans. 56, 323.

Ostwald and Nernst, Ueber freie lonen, Zeit. physik. Chem. 3, 120.
Ostwald, Affinitdtsgrossen organischer Sduren, ibid. 241, 369, 588.
de Vries, Isotonische Coeffizienten, ibid. 103.

Arrhenius, On Electrolyte Dissociation vs. Hydration, Phil. Mag. 28, 30.
Arrhenius, Ueber die Dissociationswarme, etc., Zeit. physik. Chem. 4, 96.
Nernst, Elektromotorische Wirksamkeit der lonen, ibid. 129.
Arrhenius, Reaktionsgeschioindigkeit bei Inversion des Rohrzuckers, etc.,
ibid. 226.

Nernst, Gegenseitige Beeinflussung der Loslichkeit von Salzent ibid. 372.
Arrhenius, Gleichgemchtsverhdltnisse zwischen Elektrolyten, ibid. 6, 1.

1890. Pickering, Nature of Solutions, Proc. Chem. Soc. 6, 86 and Phil.
Mag. 29, 429.

A BRIEF REVIEW OF WILHELM OSTWALD'S
"GRUNDRISS DER ALLGEMEINEN CHEMIE " 1

A SINCERE admirer of Professor Ostwald's monumental
"Lehrbuch" must regret that the present textbook should
have been chosen to present the recent developments of
physical chemistry, rather than a second edition of the
earlier, larger work. While the present volume is intended,
according to the preface, to interest in physical chemistry
those as yet unacquainted with the subject, it seems question-
able whether this object can best be obtained by cutting away
much that renders the larger work such delightful reading;
nor does it seem plausible that a non-mathematical mind
should grasp a mathematical formula better because the strict
proof is omitted as too abstruse, and that the reader who is
conversant with calculus should therefore be debarred from
this aid to the comprehension. There is no doubt, however,
that this little volume gives all the subject-matter proper of
the two older volumes, with some additions; condensation
has been obtained by employing smaller type, omitting many
tables and much purely historical matter, and, finally, by
omitting all references to titles of papers, instead of which
the year of publication has been inserted in the text. The chap-
ters have been rearranged into a very logical sequence, and
the new points of view introduced by the hypothesis of os-
motic pressure receive a very full and withal very compre-
hensible treatment.

For such as desire a rather hurried glance over a large
field, this book can be very well recommended; but it is to
be hoped that its presence in the chemist's library will not be
supposed to atone for the absence of the "Lehrbuch."

1 Reprinted from Am. Chem. Journ. 12, 516 (1890).

THE PROVINCE OF A GREAT ENDOWMENT FOR

RESEARCH l

IN response to the request for the views of American men
of science on the mission of the Carnegie Institution, I would
first of all express the hope that the trustees will reject those
propositions which would most seriously menace the free de-
velopment and untrammeled activity of our various scientific
bodies and institutions of learning — especially the establish-
ment of a huge reserve fund, with the annual distribution of
its income among the " deserving poor." It seems to me that,
while there may be occasional demands for large sums to equip
exploring parties on behalf of some of the descriptive sciences,
the legitimate demands for assistance in research in the exact
sciences ought not to be very large, in any one year; in fact,
I venture the assertion that the existence of large sums to be
devoted in this way might lead to wastefulness in methods,
rather than to the development of that resourcefulness which
has been the characteristic of the greatest investigators.
Favored beneficiaries might choose a field of work from which
others would be debarred by questions of cost, rather than
strike out upon lines of greater originality and importance.
Again, it cannot be denied that the establishment of a stand-
ard of measurement with the utmost precision is work well
worthy of national support: but if the Carnegie Institution
were to encourage, by means of its stipends, all our most capa-
ble physicists to devote themselves to this class of work, ad-
vance in this department of knowledge would be seriously
hampered. Is it a hardy prediction, however, that the votes of

1 Reprinted from Science, N. S., vol. 16, 1902, pp. 485-86.

ENDOWMENT FOR RESEARCH 47

a committee on distribution would always favor such definite
projects, as against a proposition to explore some vaguely de-
fined problem of physics or chemistry?

I think, therefore, that the proportion of the income to be
devoted to the immediate subvention of research ought to be
small at best; the aid would probably be more efficient, if
administered through existing scientific societies, who would
receive from time to time such additions to their research
funds as would seem commensurate with their previous suc-
cess in promoting investigation. The existence of a central
reviewing body would act as a wholesome restraint upon these
smaller scientific bodies, while the relative needs of investi-
gators could be better judged by a jury of experts in their im-
mediate field of work, than by such a heterogeneous committee
as would be furnished by the trustees themselves.

On the other hand, the suggestion that the institution
should play the part of a private benefactor to our universi-
ties, by adding to their endowment, building and equipping
laboratories, augmenting professors' salaries or providing
them with private assistants, seems to me to savor of paternal-
ism and to open the way to serious abuses, while at the same
time it might cause colleges to shape their course with the sole
view of pleasing the guardians of the fund, for the time being.

It seems doubtful whether any salary could be paid to a
body of academicians, sufficient to enable them to devote
their whole time to research; and it is a fair question whether
it would really be desirable to set a body of men apart in a
scientific academy, at the present day, without that contact
with students which a university provides. It must be remem-
bered that the Royal Institution of London is not an academy
in the strictest sense; nor do the resident lecturers owe a duty
to a foundation, but rather to the subscribers. With the
enormous distances separating our educational centres, it

48 MORRIS LOEB

would not be conceivable that a lecturer could assemble
around him so national an audience as would listen to a Fara-
day or a Rayleigh.

All these plans remind one of the hot-house method of stim-
ulating plant-growth; why not attempt the open-air method
of cultivating the soil? The Carnegie Institution might facili-
tate research for all, instead of offering incentives to a chosen
few. For this reason, the satisfactory equipment of marine
biological stations, open to all qualified observers, and of
similar institutions that would render the natural phenomena
more readily accessible to general study, would seem eminently
proper; while one might doubt the propriety of establishing
observatories simply for the intense study of single problems.
The efficacy of special research laboratories in the physical
sciences, such as England owes to the generosity of Mr. Mond,
has yet to be proven in contrast with that of university labora-
tories; to the writer, their establishment in this country would
appear premature, since many of our well-equipped educa-
tional laboratories are not so crowded that they would be
obliged to refuse accommodation to an independent investi-
gator who sought their hospitality.

The same general argument would oppose the financial
support of periodicals and publishing organizations, while it
would strongly favor the equipment of a scientific printing
office, for the prompt and cheap reproduction of the results of
research, for the account of individuals as well as of associa-
tions. However, if the trustees desired to obviate the most
serious difficulties which beset the American scientist in his
laboratory work, they would establish workshops for the con-
struction of special apparatus and the preparation of the
more recondite materials, such as rare chemicals, microscopic
mounts, etc. What stipend, for instance, could put the Ameri-
can chemist on a level with his German colleague, when the

ENDOWMENT FOR RESEARCH 49

latter can obtain, within twenty-four hours, any preparation
that is catalogued, while the former must allow six weeks for
obtaining anything that is not so commonly known as to be
literally a "drug on the market"? By enabling the private
investigator to supply his needs quickly and at a reasonable
cost, without the unjust discrimination of " duty-free" impor-
tation, a stimulus would be given to private research, inside
and outside the college laboratory. Who can estimate the
amount of time frittered away in this country through the
lack of ready access to the mechanical adjuncts to investiga-
tion? Workshops to supply these would not only improve our
immediate condition; but, if properly organized, they might
serve to educate a body of mechanicians and preparators,
whose help would be invaluable in the various scientific in-
stitutions of the country.

If these suggestions should illustrate the view that the
Carnegie Institution can do measurable harm by seeking to
supplant private initiative with artificial stimulus, but can do
immeasurable good by clearing away the obstacles that now
trammel the general growth of the scientific spirit in America,
they will best express the opinion of

MORRIS LOEB.

ATOMS AND MOLECULES1

IT is often a question with the scientific student as to
whether his investigation can lead to any real advancement of
knowledge, or whether the outcome will merely add to the
scraps of information that are scattered here and there in the
storehouse of human intelligence. How often, when walking
or bicycling in an unfamiliar country, does one turn into a
lane, wondering whether it is to lead one into a new highway
or end blindly , forcing the traveler to retrace his path ! Fortu-
nately, the many discoveries and inventions based on studies
by previous generations made without any expectation of a
practical outcome, have silenced those who scoff at anybody
who looks for something that cannot at once be made into a
scarf-pin or shoe-buttoner or patent medicine or the like.

Among the matters that will necessarily escape practical
application longest are the infinitely great and the infini-
tesimally small. It is true enough that astronomy is a useful
science to the navigator and to the geographical surveyor;
but it would be hard to convince me that, for many genera-
tions to come, the price of iron will be affected by our knowl-
edge that huge quantities of that metal exist in the solar
atmosphere. Nevertheless, it gives us a wonderfully encourag-
ing realization of the power of the human intellect to con-
template the steps by means of which this apparently useless
bit of knowledge was secured. How grand is the thought that
a Lilliputian man has been able to weigh heavenly bodies
far bigger than the earth itself, and so far distant that our own
distance from the sun becomes quite small by comparison!

1 A popular address evidently delivered in the spring of 1906; the place and exact
time are unknown. This address was illustrated by experiments. [EDITOR.]

ATOMS AND MOLECULES 51

Chemistry and physics, however, bring us to the opposite
end of the scale, and we are led to the assumption of bodies
that are so exceedingly small and so close together, that we
cannot conceive of their dimensions any more clearly than
we can conceive of our distance from the sun or from Neptune.
The problem of estimating these distances must, therefore,
appeal to us as similarly deprived of immediate usefulness.

There is nevertheless this difference. We are all convinced
of the existence of the stars : we follow HerschePs descrip-
tion of their multitude with amazement, but we do not for
a moment doubt the reality of his statements. The atom
and the molecule are every now and then denied reality; that
great thinker, Ostwald, who visited us this winter, has emphat-
ically expressed the opinion that matter itself is non-existent
and that the atom and molecule are conceptions which must
sooner or later be abandoned. The permanence of the atom
is assailed by the supporters of the new electron theory and is,
in a measure, shaken by recent discoveries respecting radium
and helium. How about the molecule? It is too small to be
seen, too subtle to be handled and weighed as an individual.
But we can nevertheless weigh and measure it by different
means; and because results attained in various ways agree
fairly well with one another, strong evidence is afforded of the
reality of the molecule. It would be a very remarkable coinci-
dence if three or four different processes gave us an identical
measure for a certain thing and the thing itself did not exist.
If, in traveling, we noticed a considerable number of rail-
roads converging toward a common centre, we should expect
to find something interesting and definite at that point.
Similarly, I see evidence of the probable existence of the
molecule in the fact that many lines of calculation converge
upon the same order of magnitude.

The ancient philosophers who first thought concerning the

52 MORRIS LOEB

nature of substances as we see them around us, had many
vague notions as to the causes from which the various proper-
ties of the substances might arise. One might almost say that
the various Greek philosophers devised every conceivable
notion as to the origin of matter which a sensible man could
happen upon. Among these there were two which must claim
our attention, because they throw much light upon the differ-
ing hypotheses about physical phenomena up to the present
day. One notion was that every substance is made up of cer-
tain ingredients whose presence caused it to have its own par-
ticular properties, which were really the properties of the in-
gredients. Aristotle called these ingredients elements, and
he mentioned as such elements, fire, air, earth and water, of
which he considered earth as that which was cold and dry,
water that which was cold and moist, fire that which was hot
and dry, and air that which was hot and moist. More elements
were added during the Middle Ages, so that the ancient al-
chemist spoke of six or seven different elements out of which
all known substances were imagined to be composed. Now,
since gold, silver and lead, for instance, are all composed of
the same Aristotelian elements, it seemed natural that if one
changed the proportion of these elements, lead, for instance,
might be converted into silver or gold.

To the present time we have retained the word element, but
we have given to it a somewhat altered meaning, because we
have recognized that some of the substances thought by the
ancient and mediaeval philosophers to be simple are really com-
pounds or mixtures; while many of the substances which they
considered composite baffle the skill of the chemist when he
attempts to disintegrate them. The simple metals are now all
of them considered as chemical elements; and we were until
very recently apt to look back with a good deal of scorn upon
the alchemists who strove to change one metal into another.

ATOMS AND MOLECULES 53

But they were right from their point of view, just as we are
right from ours, for with the knowledge that coal tar contains
the elements carbon, hydrogen, nitrogen and oxygen, which
are also contained in indigo, in quinine and in oil of bitter
almonds or in vanilla, we attempt to convert the coal tar into
one of these. The difference is that the alchemists failed while
we succeed, and our success is largely based upon the experi-
ence obtained from the unsuccessful efforts of our predecessors.
The other notion which originated in Greece was that of the
atoms, out of which all matter was supposed to be composed.
Democritus of Abdera is supposed to have invented the sug-
gestion that all matter is made up of little particles which
have their own separate existence and move about freely
until they happen to attach themselves to one another.
This idea occupied the attention of some other Greeks and
Romans, but during the Middle Ages it was entirely lost to
view; and in fact, its real importance was only recognized
after the already mentioned change had occurred in our views
concerning the elements. Now, under the lead of John Dai-
ton, we believe that the finest particles of which matter is
composed that we are able to recognize, are little bodies
which cannot be decomposed further by ordinary chemical
means, and which behave very much as if they were little
round pellets possessed of independent motion, and only in-
fluenced by those other little pellets that lie around them.
These atoms must have very many properties of their own,
and the different atoms do not necessarily have the same
properties. When two atoms, therefore, are alike in their
properties, we call them atoms of the same element; when the
properties differ, they are atoms of different elements. Now,
inasmuch as there are over seventy-five elements known to the
chemist, there must be at least seventy-five different species
of atoms. Whether these atoms are themselves made up of

54 MORRIS LOEB

seventy-five different sorts of substances is a question with
which we cannot concern ourselves. Some chemists choose to
believe that they are made up of only one sort of substance,
arranged in different fashion for each kind of atom, and others
have ideas that are even more difficult to grasp than this one.
But inasmuch as the chemist acknowledges that he, at least,
cannot go further in his subdivision than the atom, it is safe
for us to stop there in our study this evening. We can never
expect to see an atom, or to distinguish it by one of our senses
from its neighbor. What, therefore, the real, actual proper-
ties of the atom may be, is just as hard for us to conceive, as
it is to imagine how the inhabitants of some other planet
would look. Nevertheless, if somebody tells us that there are
inhabitants of Mars, we straightway fall to imagining that
those Martians must look more or less like ourselves, or like
something that we see on earth. In the same fashion we reason
by analogy concerning the atoms, and readily reach conclu-
sions concerning their general properties from the behavior of
the substances which they compose. Nevertheless I would
especially guard those of you who are interested in chemistry
against imagining that we really know so very much about
atoms, although we know a good deal about the elements
after which they are named.

Let us in the first place attempt to get some experimental
idea of the size of *an atom. I take here a red substance (the
well-known aniline dye called fuchsine) which is made up, as
I happen to know, of several elements; and a very little of it
gives, as you see, an intensely red coloration to a little water.
If I pour this small amount of liquid into a measuring glass,
and add to it one hundred times as much water, the color is
still very distinct, and taking one-tenth of this and again
diluting it with yet one hundred parts of water, you can still
faintly perceive the red color. Now the original weight of the

ATOMS AND MOLECULES 55

coloring matter, which covered only the point of a knife, was
barely one grain; dispersed over the great bulk of water which
you see here, it nevertheless retained its pink coloration,
which must be a proof to you how finely its substance is capa-
ble of subdivision without being decomposed. One faintly
pink drop of the most dilute solution must contain at least one
of the smallest particles of the red fuchsine; and each of these
small particles or molecules must be made up of a number of
smaller particles or atoms of four elements, one solid and
black, the three others colorless gases with which you are
undoubtedly familiar, and which make up the important parts
of the atmosphere and of water. If these four elements had
been merely mixed together, one would separate at once, as
happens now when I mix a little carbon dust with air. Hence
we conclude that in the red compound the carbon, oxygen, hy-
drogen, and nitrogen exist not as we know them, but with the
atoms joined intimately together to form a new chemical
compound; and it is only when we split this compound into a
condition bordering on the fineness of the atoms, that we can
be said to decompose it into its constituent parts. The point
to which we can reduce the compound before it breaks up is
called the molecule, often defined as the smallest portion of
the compound which can exist and still retain the properties
of that substance. In the dilution just shown, the molecules
were very widely separated and were surrounded by molecules
of water.

What, then, is the size of a molecule? This is one of the
most interesting problems that has been put before the physi-
cist, and it is a great triumph for science that four or five
different methods have been discovered for determining this
size, and that the results have been found to agree tolerably
well with one another. We are accustomed to look with more
awe on big things than on little ones; and so, when we are told

56 MORRIS LOEB

of the distance between the earth and the sun, or of the great-
ness of the sun's diameter, we exclaim at the magnitude of the
figure, while we talk unconcernedly of molecules. Is it, how-
ever, so easy to realize the exceeding smallness of the mole-
cule?

The measurement of the magnitude of molecules can be
performed in the following fashion. As a soap bubble expands
with its increasing inflation its film can be greatly stretched.
The thin bubble becomes more and more brilliant in color as
it grows thinner; and then a moment comes when the film
suddenly loses its color and becomes black. This is because a
certain thickness between the front and rear wall of a film is
required in order that the film shall show colors by reflection.
When it has become colorless, we know that we have stretched
it so that it no longer possesses this requisite thickness; it is
thinner than the length of a wave of light. In order that it
should be a continuous film, it must consist of at least one
row of molecules; therefore, a molecule is less thick than the
wave length of light is long. Immediately after the film is
stretched to this extreme thinness, it breaks, which is a proof
to us that there is not so very much difference between the
magnitude of the wave length of light and the molecule.

Another interesting method of measuring the size of a mole-
cule is to be derived from the behavior of gases as they rub
upon one another, and while this involves much that could
not be studied here, it suffices to say that the same results are
obtained as by the previous method. Still other, but yet con-
cordant results can be obtained from a study of the expansion
of gases by heat, and their contraction under great pressure.
From all these we reach the conclusion that the molecules
have some real definite size, and likewise, that they consist of
comparatively few atoms apiece.

In order that we may understand better what the rela-

ATOMS AND MOLECULES 57

tions of atoms and molecules are, I now take up some interest-
ing experiments with substances that are elements; this is
because we know that when we are dealing with a single ele-
ment no change will occur which involves more than one kind
of atom. I have here a jar of the substance originally known as
oxygen, and the arrangement is such that I am able to pass
this oxygen through various pieces of apparatus, illustrating
properties of oxygen. By simply exposing the gas to a current
of electricity I give to it entirely different properties, as you
will see when I pass a little oxygen over this piece of paper,
and then expose a strip of the same piece to the action of the
electrified oxygen, or ozone, as it is called. You must not sup-
pose that there is any electricity in this ozone which makes it
different from the oxygen. I have here some ozone made by a
totally different process, and it shows the same effect. The
ozone can be converted back into the oxygen, as you will see
when I pass it through this heated tube; it now has lost its
power of affecting the impregnated paper; it has been con-
verted back into original oxygen. In fact, all our study shows
us that the sole difference between ozone and oxygen consists
in the arrangement of the atoms; one molecule of oxygen must
be assumed to contain two atoms, and one molecule of ozone
three atoms.

If this were a single instance standing entirely by itself, the
opinion might be attacked; but we have many similar cases
in chemistry, although it is not always so easy to prove the
matter as in the case of the oxygen. I have here two specimens
of phosphorus, which to all appearances are entirely different
in their nature; the one is a coherent yellow mass, the other is
a red powder; and many of the properties are different like-
wise. This one is poisonous, that one not; this one catches
fire with great ease, the other will catch fire only after consider-
able heating. Once I have set the two a-burning, however, the

58 MORRIS LOEB

result of their union with the oxygen of the air is precisely the
same. The white, powdery oxide of phosphorus forms in each
case, and if I take the same quantity of two kinds of phos-
phorus, I shall have, in each case, the same quantity of oxide
formed. These facts prove that the two substances are identi-
cal in composition, although probably differing in the arrange-
ment of their atoms. It fact, it is a common operation of the
chemical manufacturer to convert yellow phosphorus into
red, as it merely requires heating under pressure to effect the
conversion.

Here is another element, sulphur, which shows the same
tendency to appear under different guises representing differ-
ent arrangements of the atoms. If I melt sulphur, it becomes
a thin liquid; but on heating further it thickens and cannot
be poured, even upon the inversion of the test-tube. Yet more
heating converts it yet again to a liquid; and if I now pour
it into water so as to cool it suddenly, I obtain the sulphur in
a very remarkable condition, appearing in many respects
like a gum; but it is still sulphur. This might be proved by
drying it and setting it aside in a vessel entirely free from
all other chemical agencies, when it would in time go back
into the condition of the yellow sulphur. By kneading it
in my hands, I am able to effect this conversion much more
speedily.

These and various other cases of change happening to a
simple substance, separated from other substances, force us to
assume that the actual element has undergone no change, but
that its atoms have rearranged themselves into new patterns.
Such changes are best suited to make clear to you why we
make the distinction between the molecules and the atoms.
Every substance that we know of is supposed then to be
made of molecules built up of one or more atoms. If the
molecules are broken up, or their atoms rearranged, we ob-

ATOMS AND MOLECULES 59

tain different kinds of molecules, therefore different kinds of
substance; but the atoms are not changed in the operation,
and we know no method of changing them.

You may well ask, how can we get hold of molecules in
order to study them? It is impossible to catch a single mole-
cule and examine it, or even a hundred molecules; but we have
every reason to believe that in gases the molecules behave
more independently than they do in liquids or in solids.
Hence when we wish to study molecules we begin by studying
gases. Imagine a big globe filled with inconceivably small
pellets that shoot to and fro in straight lines and never come
to rest, and you have a notion of our conception of a vessel
filled with a gas. Whenever one of these molecules hits the
side of the vessel it pushes against it and tries to push it out-
wards; the sum total of countless impulses of this kind is
supposed to constitute the pressure of a gas upon its confining
walls. If I stand on a street corner on a windy day, the mole-
cules of air strike my face, and I feel this as a direct pressure
which seems to me continuous because there are so many
billions of molecules striking my face in succession. The
more molecules there are in a given space of gas, the more
frequently they must hit the walls, and the greater becomes
the pressure. The hotter the gas is, the livelier the molecules
become; they travel faster; thus we explain the fact that
heating increases the pressure of the gas upon its confining
walls.

In the liquid or solid state, the molecules no longer travel
around freely in all directions, but hang together, and occupy
a limited portion of the vessel into which they are put, so that
it is much harder to know what they are really doing. In the
gas each molecule is supposed to be acting for itself, in the
liquid or solid they must all act together.

Interesting evidence of the fact that molecules are little

60 MORRIS LOEB

independent bodies moving in a very definite way and having
very definite size, is found in a well-known experiment known
as osmose. Suppose that in this room there was a partition
which was pierced by a number of narrow doors, and on the
one side were a number of grown persons and on the other an
equal number of children, and the order was given that they
should distribute themselves equally over the total space.
The children, moving more quickly, and having no difficulty
in squeezing through the narrow doors, would soon get over
to the other side, while the grown persons were still struggling
to get through. The result would be that at first the actual
number of people on that side of the room where the children
had first been would be less than the number on the other
side. Now, instead of persons, I take light and heavy mole-
cules, the lightest molecules we know being hydrogen, and the
molecules constituting the gases of the air being over fourteen
times as heavy. In order to imitate the partition wall, I take
this tube made of porous porcelain; the openings are so fine
that we may well imagine the gas molecules having some trouble
in getting through. If I fill the inside of this tube with air,
and now fill this jar outside with hydrogen, the hydrogen will
get in very much faster than the air can get out, and the result
will be that we have a larger number of particles or molecules
per cubic inch inside than there were originally; they have
to find more room for these, and you see how they obtain it,
by pressing this liquid out in a sort of fountain. If I reverse
the experiment, I obtain the opposite effect. There is a rather
ingenious practical application of this principle which is per-
haps worth showing. Instead of holding water to be pressed
out, this tube contains mercury; as the liquid metal is pressed
down it will rise on the opposite side and make an electric
contact, which causes this bell to ring. Instead of taking
hydrogen I shall this time take illuminating gas, — and here

ATOMS AND MOLECULES 61

you see how soon an alarm is given. Such an arrangement
might well be used where a dangerous or harmful gas is apt to
appear; it was really invented for coal mines, in which there
is a danger of the formation of explosive mixtures of lighter
combustible gases with air.

In this way it is possible to distinguish, as you see, between
lighter and heavier molecules. This method may be of value
to the investigator, as we shall see. I have here a substance
whose molecules are fairly large; they are ordinarily in a solid
state, and they represent a substance which is neutral, as we
say in chemistry, — a salt that has no effect upon vegetable
colors. I throw a little of it upon these pieces of red and blue
litmus paper, and you see that there is no change. Now a
piece of this salt (which we call chloride of ammonium) is
placed in this glass tube next to a porous partition wall; when
I warm the salt it breaks up into two substances called am-
monia and hydrochloric acid, which may be separated by the
method of osmosis just used to ring an electric bell. The
ammonia consists of molecules so light that it passes very
readily through this partition wall, while the hydrochloric
acid with heavier molecules passes less readily. You will be
able to notice this when I pump air through both parts of the
apparatus and let the two currents of air flow over these two
pieces of colored paper. You see how the red paper is turning
blue, and the blue paper is turning red; this is due to the fact
that the hydrochloric turns blue paper red and more of it re-
mains on the near side of the partition; the ammonia turns
red paper blue, and more of it has gone through the partition.
The experiment not only illustrates to you what I have shown
before in a somewhat different form, but it also shows us that
the big molecules of chloride of ammonia can be broken up
into two sets of smaller molecules, which themselves differ
from one another in size. We can even, although I am unable

62 MORRIS LOEB

to show it here, break up this hydrochloric acid and this
ammonia into still smaller molecules, and beyond these still
are supposed to be the atoms. Every rearrangement of atoms
into molecules produces a new substance, and it is the marvel-
ous ability of the atoms to arrange themselves into hundreds
of thousands of ways that enables the organic chemist to
build up out of three or four elements the many compounds
which nature is building up for us daily and hourly in plants
and animals.

Such then, is the idea entertained by the chemist of to-day
concerning the nature of the mechanism carrying out the
changes which it is his business to study. But we must re-
member that this idea is hypothetical — it is no more than a
plausible guess. While the few master-minds of a century
can grasp such theories as pure abstractions, uninfluenced by
preconceived notions, the rest of us cannot free ourselves of
the prejudices derived from the familiar phenomena upon
which the theories are based. We are as little able to strip our
imagined infinitesimal particles of Matter and Energy from
the attributes of the grosser masses of our daily observation,
as was the Greek to impart other than human qualities to his
gods, whom he portrayed in human form. This is one of the
reasons for the many more or less fantastic attempts to over-
turn the atomic theory as it now exists. I do not believe that
the theory is perfect or ultimately correct, but a study of
most of the attacks upon it leads to the conclusion that the
attack is made, not upon the pure theory, but upon that par-
ticular image which has been set up to represent the theory
in an iconoclast's intellectual neighborhood. Thus we some-
times find persons who imagine they are attacking the atomic
theory, when they contend only against the gratuitous idea
that 'atoms are hard, round pellets, rather than vortices of
an infinitely elastic fluid or the like. But we have no time

ATOMS AND MOLECULES 63

to-night for these objections and criticisms, — it is enough if I
have succeeded in giving you some idea of what the chemist
means by atoms and molecules, and how these conceptions
help him to explain and understand the intricate and subtle
processes of chemical reaction.

HYPOTHESIS OF RADIANT MATTER1

THE enormous literature which has developed from the
discovery of radium and from the study of cognate pheno-
mena has made it increasingly difficult to form a calm
opinion upon the merits of all the claims which have been
advanced, and upon the validity of the theories which have
been based upon them. Undoubtedly, the great bulk of the
experimental data is exact, although time may show that
some of the results which were recorded before the technique
was fully developed may require correction. Without ques-
tioning in the slightest degree the experiments reported
by some of the skillful observers of modern times, one is,
nevertheless, permitted to hesitate in adopting hypotheses
that not only subvert formerly accepted ideas, but also seem,
in many cases, inconsistent with one another.

The chemical world has been accused of accepting too dog-
matically the theory of the conservation of matter, the in-
divisibility of the atom, etc. Ought we not, then, to guard
ourselves against a similar fault in adopting newer views?

I propose to take up seriatim the methods of reasoning
which have led to the present hypothesis of radiant matter
as expressed by its chief exponents, and to indicate some
points which seem to me to be inconsistent with older views,
or in conflict with one another; and I shall begin with what
may, from the present point of view, be called a static
phenomenon, the behavior of the atom toward light. It is
known that Lorentz modified Maxwell's electro-magnetic

1 Extracts from a review presented to the New York Section of the American
Chemical Society at its meetings, November, 1907, and published in The Popular
Science Monthly, 73, p. 52, July, 1908. Reprinted by permission.

HYPOTHESIS OF RADIANT MATTER 65

theory of light, by assuming that the vibrations from which
light-waves originate are not produced by the atom as a
whole, but rather by the vibration of its positive or negative
electric charge conceived as a special entity, which we may
now personify, as it were, by the more recently coined name
" electron." The electron vibrates in an elliptical path which
is really the result of two circular oscillations in opposite
directions, and of differing amplitudes, but of identical period.
An alteration of the radii of these circles would merely alter
the shape of the ellipse; but if the periods of the two circular
motions were made to differ, no single resultant could appear,
for the two vibrations would produce waves of different length,
i.e., light rays of different refrangibility. Now, a magnetic
strain ought to exert some influence on an electron; if it
accelerated its dextrogyratory motion, it would retard its
laevo-gy ration, or vice versa. This is precisely what Zeeman
found when he examined the emission-spectra of vapors that
were placed in an electromagnetic field; single lines are broken
up into two or more finer lines, placed symmetrically with
regard to the position of the original one. Righi has general-
ized the reasoning so that it covers practically every relation
between the vibrating electron and the external magnetic
strain to which it is subjected, and reaches two conclusions:
First, the vibrating electron is electro-negative; second, the
ratio e/m, i.e., electric charge over mass, is about 1000 times
as great as the ratio between the electric charge and mass
of the hydrogen ion. Assuming, perhaps arbitrarily, that the
electric charge is the same, the mass of the electron is about
1/1000 that of the hydrogen ion; it can be no mere coinci-
dence that Thomson, Kaufmann, and others arrive at vir-
tually the same figure for the mass of the corpuscles which
carry the negative charges in ionized gases of whatever chemi-
cal constitution; in fact, everybody recognizes their identity.

66 MORRIS LOEB

To quote Righi, the neutral chemical atom (as distinguished
from the ion) consists of a central mass of positive charge,
around which revolve as satellites one or more electro-
negative corpuscles, retained in their orbits by some centrip-
etal force.

In connection with this definition, the following points
seem to require emphasis: the number of electrons per atom
are few, practically corresponding to the valency; this
seems to be corroborated by recent experiments of Becquerel
on the phosphorescence of uranium minerals at low tempera-
tures, which likewise point out that light-emission is not
always confined to the negative corpuscle, as Righi would
have it. The total mass of the free electrons in an atom is
not sufficient to affect the ratio between specific heats for con-
stant pressure and constant volume of monatomic vapors,
like mercury and cadmium; their velocity in their orbits does
not approach that of light, and they have no high momentum
retained by comparatively powerful internal attractions.
These electrons can not be identical with the X-particles
which are projected with terrific force from the uranium,
radium and other atoms, according to Rutherford and his
followers.

I need only touch briefly on the electric discharges in vac-
uum tubes: it is generally accepted that we distinguish
Lenard or cathode rays, which are negative, and positive
Goldstein or canal rays within the tube. They can be de-
flected by electric or magnetic fields, they produce mechani-
cal and heating effects, cast visible shadows, etc., and they
behave in general like streams of actual particles charged
with electricity. When the cathode ray strikes an impene-
trable obstacle, like glass, the X-rays are produced as a sec-
ondary effect: these do not behave as if conveyed by neutral
particles; have vast penetrating power; contain no electric

HYPOTHESIS OF RADIANT MATTER 67

charge, as they are not influenced by magnetic or electric
fields, and are neither refracted nor reflected. Ijwould em-
phasize, however, their ability to discharge an electrometer,
as well as to influence the photographic plate. Their peculiar-
ities have been recently ascribed to the fact that they repre-
sented aperiodic impulses given to the luminiferous ether
— which conveys no meaning to my mind, excepting that they
can not be explained by the undulatory theory. The velocity
of the canal rays has been determined, and the mass of their
hypothetical particles measured by the amount of their de-
flection in magnetic fields of varying strength; both values
approximate those found for the ordinary chemical atoms
or molecules; in the case of the negative cathode rays, how-
ever, the velocities and mass correspond to those assumed
for the electrons. I confess to a serious difficulty in harmon-
izing the notion of a corpuscular structure of the atoms with
the explanation given by the same school for the need of
high vacua for the production of cathode rays. It is said
that the electrons must have a considerable free path in order
that they may travel with undiminished velocity toward the
anode: but if the atoms, instead of being compact elastic
bodies, be mere nebulae of electrons, the relation of whose
sizes and interstices is comparable to that of the molecules
in a normal gas, it follows that a free electron, hurled vehe-
mently forward from the cathode, could pass quite through
a number of atoms without collision with any of their con-
stituent corpuscles; the free path of the electron is so enor-
mous, on this hypothesis, that the order of its magnitude
could not be materially affected by the degree of rarefaction
of the gas customary in the Crookes tube.

We must recollect, however, that the hypothesis, first
elaborated by Larmor, that the electrons are the primordial
constituents of the atoms, does not, like that of Prout,

68 MORRIS LOEB

simply extend the limits of the divisibility of matter. The
electron is not to be considered as a small speck of matter at
all, but as a permanent manifestation of energy concentrated
on a minute portion of the luminif erous ether. The view and
the explanation of many phenomena on such a basis has been
acclaimed as the triumph of energetics, the final elimination
of the conception of matter. An unbiased reading of J. J.
Thomson's Yale lectures, however, will impress anybody
that he decidedly materializes both energy and ether. Per-
haps much of this materialization is purely symbolic, to bring
his mathematical reasoning within the comprehension of his
audience; but to me it seems that an electric charge which
has quantity, mass, inertia, elasticity, and expansibility, which
obeys the laws of hydrostatics, and virtually has a surface
beyond which it can only produce effects by the medium of
mysterious lines of force, has a marvelous resemblance to the
picture which the ordinary chemist's mind would form of
material substance. His ether is not only that puzzling para-
dox, at once impalpable and inconceivably dense, rigid and
frictionless, which we have accepted as the whole means of
explaining the transmission of motion through a vacuum;
to extend its importance as the substratum of all phenomena
it must become heterogeneous and capable of deformation;
to form a neutral atom, some of it must become a spherical
jelly in which other parts of itself are imbedded as rigid par-
ticles. It has, consequently, different degrees of hardness,
and is subject to internal attractions. Thomson even volun-
teers the admission that, for the explanation of certain
phenomena, his ether must have structure, or, at least, be
stratified.

This can, of course, be no insinuation against the work of
some of the greatest living physicists and mathematicians:
accepting their premises, I do not doubt that they have

HYPOTHESIS OF RADIANT MATTER 69

drawn the consequences in the most rigid fashion. I do assert,
however, that some of their fundamental terms are used in a
different sense from that to which we are accustomed, and
that we are, therefore, entitled to doubt whether the con-
clusions which they reach really affect the phenomena with
which the chemist deals: as if one were to discuss the crystal-
lographic structure of Pentelian marble with reference to the
architecture of the Parthenon.

A few examples, pertinent to our inquiry, will more pre-
cisely establish my meaning. One of the fundamental postu-
lates of Professor Thomson's mathematical argument is the
definition of momentum as the product of mass by velocity.
Although this is not axiomatic, we accept it as such by reason
of the many ballistic experiments which have proved its truth,
so long as the projectile's mass was assumed to remain con-
stant: we should hesitate if we were told that mass was to
vary, i.e., that a bullet which weighs the same before and after
the shot, was heavier during its flight. But the momentum
of Thomson's electrons increases faster than their velocity,
when the latter approaches that of light; hence, he says, the
mass of the electrons increases with their swiftness. True, he
calls it an electro-magnetic mass, but some of his followers
have forgotten the distinction. At all events, his terms " mo-
mentum " and " mass " must not be accepted by us in their
usual meaning.

It is perfectly true that Thomson's calculations are corrob-
orated by Kaufmann's experiments on the velocity of
radium rays in combined electric and magnetic fields, if the
latter 's data are calculated according to Thomson's views;
without even seeking a radically different basis — which
would not be difficult — we can follow Thomson to a point
where his departure from ordinary assumptions becomes evi-
dent. He shows that the value elm diminishes at high veloc-

70 MORRIS LOEB

ities and then he assumes that e> the electrostatic charge,
is constant; therefore m, the mass, varies. Now, the value
of e is derived from Faraday's law, which would never have
been announced if Faraday had not dealt with the equivalent
weights as fixed mathematical quantities. In fact, just so
far as Thomson substantializes electricity by giving it atomic
structure, with invariable mass, the chemical atom becomes
wavy and matter evanesces into the ghost-like form which
energy has assumed in the chemical mind. If our scientific
terms are, as it were, to receive the reciprocals of their present
significance — progress may ultimately result, but we should
enter into topsy-turvy dom with our eyes open.

The electron theory possesses the merit of furnishing a
working hypothesis upon which to coordinate the various
electrical phenomena of vacuum tube and radio-active origin :
chief among which is the increased conductivity of gases.
Either direct current measurement or the more sensitive
electrometer, determinative of the decrease of electrostatic
potential, indicates that gases begin to conduct electricity
when affected by ultra-violet light, by cathode and X-rays,
by radium, thorium, etc. Ingenious experiments have proved
that portions of the gas are positively, others negatively,
charged; that they behave as if ionized; the numbers, masses
and charges of the hypothetical ions have been measured and
found to agree with the assumption that the negative ions
have the magnitude of the electrons, the positive ions that of
the regular molecules, i.e., the negative ions are always very
small and mobile, with the same value for all gases; the posi-
tive ions are, at least, 1000 times as large, and vary for dif-
ferent gases. If the gas moves away from the locality of ion-
izing influence, its conductivity disappears gradually at a rate
to suggest reunion of the ions. Plausible, if not quite conclu-
sive, reasoning connects the ionization hypothesis with the

HYPOTHESIS OF RADIANT MATTER 71

novel phenomenon of the saturation constant; viz., the fact
that the flow of electricity through a conducting gas increases
proportionately to the voltage between the electrodes up to
a maximum, when further increase of potential has practically
no effect on the current. This saturation current, it may be
remarked, is used to characterize radioactivity; it is admit-
tedly a complex phenomenon, and I should be inclined to lay
more stress upon the qualitative than the precise quantita-
tive results obtained in a number of recent experiments.

Those who, like Armstrong, oppose the electrolytic dis-
sociation hypothesis of Arrhenius, naturally attack the ioni-
zation hypothesis with still greater vehemence, and I believe
that this will be the battleground of opposing theories for
some time to come. As the phenomenon is distinctly a sec-
ondary reaction, from our point of view, we need not discuss
it in its various aspects, beyond noting that even without
detectable radioactive agencies the atmospheric air conducts
electricity to a slight extent, varying with location, as well as
with the hours of the day.

The radiations from the active chemical substances present
a very complex aspect; besides light and heat, radium and
its congeners send out a-, J3-, and 7-rays, respectively elec-
tro-positive, electro-negative and neutral when tested in elec-
tric and magnetic fields.

From radium a-rays are sent out about four times as abun-
dantly as /3-rays, the 7 variety being relatively few. a-rays
are electro-positive, have a speed one tenth of the velocity
of light, and a molecular mass of atomic magnitude. They
penetrate a few centimeters into air, pass through thin
aluminum foil but are stopped by denser metals. As they
are but slightly deviable in a magnetic field, their momen-
tum is calculated to be enormous; until, however, better evi-
dence of the total positive charge which they carry has been

72 MORRIS LOEB

obtained, we cannot consider the magnitude of the momen-
tum as definitely established; especially since their speed
does not appear to be uniform. From experiments wherein
a particles are allowed to escape freely, and again restrained
by a lead cylinder surrounding radium, much of the appar-
ent heat of the latter body appears to be due to the impinging
of the a-rays upon the surrounding surfaces.

/3-rays are similar to cathode rays; they are less absorb-
able than the a variety, and proceed at various speeds, many
approaching the velocity of light; they are stopped by solids
in proportion to their density.

7-rays are similar to X-rays, of great penetrating power,
and they are thought by some to be secondary effects of a-
and /3-rays, just as the X-rays originate from the impact of
cathode rays on the glass wall of the Crookes tube. Besides,
we have a multitude of conflicting accounts of secondary
tertiary rays, resulting from these three varieties.

The chief method of research is the study of ionization,
with the interposition of screens and magnetic fields, to
separate the different kinds of rays. On the other hand, the
varieties of rays emitted, their relative strength, and their
variations of intensity, are the characteristics upon which
the identification of the various so-called transformation-
products of radioactive material is based. I have, therefore,
copied from Professor Rutherford's book 1 tabulations of these
properties.

With regard to these various transformations, we should
realize that the majority of the names are titles of hypothet-
ical substances whose existence within certain mixtures is
assumed upon the evidence of their momentary radioactiv-
ity. The only one really isolated is that emanation which has
all the properties of a gas, including that of condensibility

1 Radioactivity, 1905.

HYPOTHESIS OF RADIANT MATTER 73

at low temperatures — with the exception that its liquid
form shows no vapor pressure — but has in addition remark-
able energy effects, and has, undoubtedly, undergone trans-
formation in Ramsay's hands. Bearing in mind the infinitesi-
mal quantities of emanation which Ramsay and his associates
could obtain, we are alike astounded by their marvelous
manipulative dexterity and by the nature of their observa-
tions. First we had the gradual appearance of helium, when
the emanation was stored by itself; then came the appearance
of neon, when the emanation came into contact with water,
the latter being partially decomposed into oxygen and hydro-
gen; lastly the partial reduction of copper nitrate solution,
with the simultaneous appearance of lithium, while the ema-
nation underwent a change into argon. The lithium, we are
assured/ could not be found in the original materials; it repre-
sents about .01 per cent of the sodium and calcium found in the
same experiment; its actual amount, after correcting a slight
oversight in Ramsay's estimate, would be 0.00000003 gram.
For such a quantity the amount of copper transformed would
be too minute for the detection of a loss from the 0.3 gram
of copper which the original solution may be assumed to have
contained: but, until a loss of copper be ascertained, to corre-
spond with the gain in lithium, it appears to me that the as-
sumption of transformation is premature. Ramsay found that
this solution contained in all 1.67 mg. alkaline chlorides,
chiefly sodium chloride; while 0.79 mg. was produced in a
blank experiment, when the emanation was excluded. While
this latter amount is admittedly derived from the glass bulb,
the excess obtained in the presence of emanation is ascribed
to the degradation of the copper, neglecting the fact that this
second solution must have been fairly acid and would, there-
fore, have attacked the glass more vigorously. Accepting his
suggestion, however, the deficit of copper ought to approach

74

MORRIS LOEB

TRANSFORMATION PRODUCTS OF THORIUM, ACTINIUM, AND
RADIUM ACCORDING TO RUTHERFORD

Product

Time to be half transformed

Radiations

Thorium

a-rays

1

Th.X

4 days

a-rays

I

Emanation

54 seconds

a-rays

I

Thorium A

11 hours ^

no rays

1 >*33

Thorium B

55 minutes J

«-. /3-» 7-rays

i

Actinium

p

no rays

Actinium X

10.2 days

a (0 and 7)

Emanation

3.9 seconds

a-rays

Actinium A

35.7 minutes

no rays

Actinium B

2.15 minutes

a, /3, and y

Radium

1,200 years

a-rays

I

Emanation

3.8 days

a-rays

i

•

Radium A J "o «

3 minutes

a-rays

Radium B ? 3

21 minutes

no rays'*

Radium C J <

28 minutes

o-, 6-, 7-rays

i

Radium D *s w>

about 40 years

no rays

i 1-5

Radium E w ^

6 days

/3- (and "y-)rays

1 2 0

* '-§53
Radium F J .§ «g

143 days

a-rays

i

HYPOTHESIS OF RADIANT MATTER 75

0.8 mg., an amount which ordinary analysis can detect. We
may, therefore, hope that further experiments by Professor
Ramsay will throw light upon this side of the subject.

Of Ramsay's present conclusion, the following resume may
be given: Emanation is a gas of about atomic weight 216.5,
derived from radium, of atomic weight 225, simultaneously
with a-particles which are not helium. When emanation and
the a-particles are shut up together, the bombardment of
the latter breaks up the emanation into helium; but if heavier
molecules, like water, be present, they receive some of the
bombardment, and the emanation is only degraded into
neon; the pressure of copper nitrate still further protecting
the emanation, so that it only breaks down to argon. This
kinetic explanation is not impeccable; for, according to the
principles of mass-action, the preponderance of water mole-
cules in the copper nitrate solution, as well as the predomi-
nance of hydrogen and oxygen in its decomposition products,
would imply the presence of considerable amounts of neon to
accompany the argon. As neon is said to be absent, we must
either seek some other hypothesis or explain how the neon
reverts to argon after it is once formed.

Ramsay's views contradict those of Rutherford and others,
who seek to identify helium with the a-rays, and the latter
would thereby lose a good deal of their substantive character.
Furthermore, it is to be noted that the a-particles bear posi-
tive charges: if they were merely chemical atoms, such a
charge might possibly be obtained as they tore themselves
loose from the larger complex, during radiation; but if they
be non-substantive masses of free energy, it will be difficult
to reconcile the various assumed transformations with the
electro-chemical properties, valencies, etc., of the elements
in question.

It must be recalled that Rutherford does assume that the

76 MORRIS LOEB

successive transformations of radium, for instance, are ef-
fected by the expulsions of the a-particles and that these have
atomic mass: an atom of radium, therefore, contains a finite
number of them. As the transformations are atomic and
not molecular, Rutherford's application of the mathematics
of mass-action can mean but one thing: that the various rates
of transformation depend upon the chances of encounter
and relative positions of the particles within the atom. These
rates, however, as measured by the period of decay, vary from
thousands of years to a few seconds for the different educts,
and that irregularly in the order of transformation — such
great differences could only be explained by an infinite number
of components, with large free paths, — in other words, elec-
trons. It would then remain to be shown what caused a
certain great number of negative electrons to form an electro-
positive a-particle, and become expelled with great violence
from their surroundings.

Naturally, the failure of an hypothesis to explain certain
facts does not invalidate the latter. Rutherford's brilliant
analysis of the curves of increasing and decreasing ionization
and the agreement observed with calculated results prove that
he is not dealing with mere fortuitous coincidences. Many of
his conclusions seem incontrovertible upon his premises;
but here again, the advocatus didboli must step in and ask
whether the premises are axiomatic: two of them appear to
me to be doubtful. (1) A curve of decay is based on electro-
scopic measurements upon the tacit assumption that the rays
sent out by that particular phase are always the same; but we
are told that both a- and /3-rays vary greatly in speed and
momentum, hence neither variety would show a uniform ion-
izing power; assuming that a substance did send out a-rays
for a long time, but that their velocities were gradually re-
duced, would not the ionization indicate a more rapid decay

HYPOTHESIS OF RADIANT MATTER 77

than was really the case? (2) It is practically assumed
throughout that ionization is directly proportioned to the
amount of radio-active material present: but this remains to
be proved. Where layers of any density are involved, we
know that it is not true, owing to internal absorption, etc.;
for ideally thin layers, weighing and other measurement are
out of the question.

I do not think that this latter objection ought to be dis-
missed lightly, when we find such a phenomenon as the al-
most universal ionization of the atmosphere ascribed to the
presence of radium or its educts. Thomson himself has shown
a variety of ways for ionizing air, when any variation in the
amount of radium present — or, rather, absent — is out of
the question; some of these serve particularly well to explain
the phenomena in the open air. Recently, indeed, quite a
number of investigators have observed diurnal variations in
this atmospheric ionization, sufficiently marked to require
some other explanation than the production of emanations
from the earth or surrounding materials. Gustave Le Bon,
in his "Evolution de la Matiere," shows how the gold-leaf
electroscope is discharged when connected with some very
dry sulphate of quinine, which is taking up hygroscopic
moisture. Are we ready, with him, to assume that the quinine
is catalyzing some atoms into Nirvana, or that the electro-
scope may indicate many changes that are not intra-atomic?

REPORT OF THE COMMITTEE OF THE OVER-
SEERS TO VISIT THE CHEMICAL LABORATORY
OF HARVARD COLLEGE

To THE BOARD OF OVERSEERS OF HARVARD COLLEGE: —
Your Committee beg leave to report that they visited
the Chemical Laboratory on Tuesday, March 9th, 1909,
and were received by Professors Jackson, Sanger, Richards,
Torrey, and Baxter, and Dr. Henderson. At the opening of
the meeting an expression of deep regret at the recent death
of Dr. Wolcott Gibbs, Professor Emeritus and distinguished
chemist, was recorded. After the reading of reports on the
present condition of the building, and some discussion, the
Committee were shown over the laboratories.

The condition of the laboratories in Boylston Hall has been
so fully set forth in previous reports that it seems now hardly
worth while to repeat in full the criticisms as to their condi-
tion, which have been so repeatedly made. It may be, how-
ever, of advantage on this occasion to refer to one or two
points of pressing importance. The needs of those desiring to
study chemistry at this University may be divided into two
classes: first, the needs of the undergraduates, and, second,
the needs of those conducting research.

So far as the undergraduates may be concerned, the most
pressing necessity at the present time is for the better accom-
modation of students in qualitative analysis. The space as-
signed to this work has been so inadequate that additional
accommodations have been found for the students in the
west wing and basement of Dane Hall. For those who are
working in what is now termed Chemistry 1, there is such

REPORT ON CHEMICAL LABORATORY 79

imperfect accommodation that about half of the students
have been forced to carry on work in the unsanitary cel-
lar, now called Room A. There is no space anywhere for
laboratory instruction in elementary organic or in technical
chemistry.

Turning now to the needs for research : For organic research
the accommodation is fair, but not ample or comfortable.
For inorganic and physico-chemical research the facilities
are very bad, and for technical research there are no facilities
at all, nor is agricultural, sanitary, or biological chemistry at
all provided for in Cambridge.

In precise investigation of atomic weights, Harvard prob-
ably leads the world. Such work demands well-ventilated
rooms, free from dust and noxious vapors of all kinds, — for
these may ruin the purity of the substance to which months
of care have been devoted. Researches in physical chemistry
need rooms of constant temperature, free from vibrations
and changes in electrical field. This work is now so badly
provided for that it is greatly hampered.

The lecture-rooms, which for the most part were designed
at the time of the first occupancy of Boylston Hall in 1857,
are now not only inadequate for the number of students to
be accommodated, but are lacking in ventilation, and are too
few for the proper preparation of experimental lectures.

One of the most important needs at the present time is a
better provision for the administration of laboratory and
storeroom, — a very important feature in the economical
carrying on of a well-conducted laboratory.

When the present building was built, there were about one
hundred students in the required lecture and recitation course,
but few laboratory students. The number of the latter stead-
ily increased from time to time, and the other departments
of the University which also found room in Boylston Hall

80 MORRIS LOEB

were gradually crowded out, until in 1900 every nook and
corner in the building which could be utilized had been ex-
hausted. The consequence was that when over six hundred
men applied for desks that year there was a waiting list of
forty men. This continued for several years, and the Univer-
sity was in the position of not being able to make good its
announcements concerning chemistry. With this overcrowd-
ing, a steady deterioration has taken place in the equipment
of the building, and the result is that many men are now de-
terred from taking the elementary course in chemistry on
account of the known conditions of the laboratory. It is also
probable that many students do not go on with advanced
work on account of the unfavorable conditions under which
they have to work.

It has been suggested that the present building should be
entirely refitted internally, but its arrangement at the present
time is so entirely unadapted to alterations of any kind that it
would be necessary to tear out the whole interior of the build-
ing, and even then it is not probable that a satisfactory ar-
rangement of a new set of laboratories and lecture-rooms on
a modern basis could be planned within its four walls, as
careful measurements of Boylston Hall show that the avail-
able space within the walls would not be adequate for the needs
of the department if the building were to be remodeled. A
further use of Dane Hall, aside from the obvious inconven-
ience of two separated buildings, would not give sufficient
room for expansion. In short, any remodeling or enlarging of
present quarters would be but a makeshift. For this reason
it was borne home strongly to the members of the Committee
as it has been for a long time to the members of the teaching
staff, that these needs can be met in an adequate way only
by the construction of a number of new buildings, — the
separate buildings being devoted to different branches of

REPORT ON CHEMICAL LABORATORY 81

chemistry, and placed not far apart, to be connected with
each other by a central Administration Building. The latter
might contain also the chief lecture-rooms, a chemical museum,
as well as a library, and other facilities to be used in common
by all; separate buildings, as has been stated, to be devoted
to the different branches of chemistry. One could be devoted
to organic and industrial chemistry; a second to inorganic
chemistry; a third to physical chemistry, and a fourth to
quantitative and qualitative analysis. Portions of one or more
of these buildings could be set aside as research laboratories,
of their respective kinds. In this way provision would advan-
tageously be made for the adequate separation of work in-
jurious to other parts, either because of noise, vibration, or
noxious gases; on the other hand, connection with the cen-
tral Administration Building would promote unity of interest.

Preliminary sketches of several ways in which these build-
ings might be arranged were shown to the Committee. Such
a scheme of a group of buildings devoted to chemistry would
necessarily demand considerable space of ground, but the
Committee understand that land for this purpose is available
in Cambridge in a situation which would not only be well
adapted to the purposes of the buildings erected upon it, but
would enable them to become an ornamental addition to the
various groups of buildings now in the University grounds.

Such a proposed radical departure of the administration
of the Department of Chemistry would undoubtedly involve
a large expenditure, but when we consider the importance of
the subject and the character of the teachers and investiga-
tors who are interested in this department of science, we do
not hesitate to recommend most urgently that steps be
taken in order that a beginning may be made to work out an
entirely new foundation for this department.

With the immense development of the various departments

82 MORRIS LOEB

of science which has taken place since the chemical depart-
ment was first established on its present basis, attention has
been so acutely drawn to other fields of labor that the public
has failed to grasp the important rdle which has been played
by pure chemistry in almost all of the departments of indus-
try and science which have contributed toward the advance-
ment of the material prosperity of mankind. It seems proper,
therefore, to call attention at this time to the r61e which
chemistry has played in this great awakening of science in its
application to humanity.

In the first place, in this age of steel, much depends upon
the chemical manufacture of the various kinds of hardened
iron. As iron does not occur in commercial quantities in a
native state, the preparation of all the enormous quantity
which is used depends entirely upon making a sufficiently
pure product by a method which avoids unnecessary waste.
Both the elaboration of the method and the determination of
the purity of the material can be accomplished only by trained
chemists; moreover, the protection of the finished product
from the chemical change of rusting lies also in the same hands.
When one takes into consideration the fact that steel serves
not only a chief role in the construction of ships, bridges,
and buildings, but also is concerned in the manufacture of
almost every article which we use, because of the need of
steel tools of suitable quality, one can see how great an in-
direct part chemistry plays in every act of our life. Indeed,
all the building materials of the future, such as the composi-
tion of concrete, and the manufacture of glass and of pottery,
present at the present time chemical problems of enormous
interest.

Another great industry, the soda industry, is, of course,
wholly chemical, and so is the soap industry, which depends
upon it. Before chemists had shown the world how alkalies

REPORT ON CHEMICAL LABORATORY 83

could be made on a large scale, these all important sub-
stances were to be obtained only from the ashes of wood and of
seaweed. The consequence was that both soap and glass were
very expensive, and the result to the growth of civilization
was lamentable. The cleanliness, and therefore the health,
of the world is due to Leblanc, and since then to Solvay, two
chemists who have made soap cheap enough to replace the
mediaeval perfumes which were made to conceal the dirt.

The two great departments of applied biological chemis-
try are medicine and agriculture, and it is only now that sys-
tematic and hopeful attempts are being made to apply chemi-
cal knowledge broadly in these fields. Already there can be
no doubt that progress in this direction in the next few
decades will be enormous. It has been arrested during the
last five or six decades because pure chemistry, after develop-
ing for years in connection with medicine and agriculture,
found itself at a point where it had to turn to a systematic
development of its whole field. Now, however, this develop-
ment has gone on so far that much can be done with our pres-
ent knowledge of organic chemistry and physical chemistry,
and much more will be possible in the future if this develop-
ment of pure chemistry goes on with the same acceleration
as in the past.

For the welfare of the human race, it is essential that this
acceleration should continue, and there is no loftier public
service than advancing these activities. The advantageous
results of dealing scientifically with such subjects are to be
found everywhere in health and comfort, in relative freedom
from pain, in increased immunity to disease, so far as medi-
cine is concerned; in greatly lessened labor and enormously
increased efficiency of labor, resulting in wonderful increase
of productivity, and general economic amelioration for scien-
tific agriculture.

84 MORRIS LOEB

In the industries in which fermentation is a problem to be
dealt with, individual chemical research plays an important
role, and it was while pursuing such investigations that Pas-
teur discovered the great r61e of bacteria, revolutionizing at
the same time the whole domain of another department of
science, — medicine.

In agriculture we find a striking example of the value of
pure science, for here it was that the investigations and ex-
periments of Liebig clarified and simplified the subject.

The fertility of the earth depends upon the chemical man-
ures, and it is calculated that in thirty years the present source
of nitrogen (Chile saltpetre) will be exhausted. The loss of
nitrogen in combustion, and otherwise in civilization, is a
permanent one. Chemical means exist for getting it back
from the air. With power from electricity producing a high
temperature, we can get nitric acid from the air, so that the
danger of giving up intensive agriculture from lack of nitrog-
enous manure has been averted by chemistry.

The chief product of farming is starch, which forms the
bulk of all edible vegetables, for that is the chief food of
man, and in a larger degree it is the chief food of the herb-
ivorous domestic animals. The amount of starch which is
consumed as food by man and the domestic animals in the
United States alone cannot be far below fifty million tons
per year. In addition to this enormous use of the sub-
stance, great quantities of it are being converted into glu-
cose and into alcohol, and the use of starch for these
purposes as our scientific technology develops in this di-
rection, promises to be far greater than at present. We
may, indeed, expect that glucose will largely replace cane
sugar, and we are now assured from our present improved
devices that alcohol may be, at need, substituted for coal
and the products of petroleum in the production of heat and

REPORT ON CHEMICAL LABORATORY 85

power. The technology, then, of an inconspicuous substance,
if we may use the term, such as starch, becomes at once one
of the greatest problems in the whole field of economics, the
proper treatment of which depends upon the past achieve-
ments in the field of pure chemistry and progress to come in
that field.

The development of paper from wood pulp is now a source
of great danger to our forests. The question of getting
pulp from straw and cornstalks for this purpose becomes,
therefore, an important one, in the solution of which the
prosperity of the country is intimately involved.

The improvements of our textile fabrics, such as the manu-
facture of artificial silk, have great possibilities for advance-
ment.

All the new processes for reproducing photographic pic-
tures are largely chemical problems, as are also coinage,
chemical assaying, and the whole domain of metallurgy.

Coming now to the medical side of the question, we see at
once that the science of nutrition and the value of every dif-
ferent kind of food in the maintenance of health, and its
adaptation to disease, are all chemical problems, which are
becoming topics of increasing interest to those who are assist-
ing actively in the advance of practical medicine. The actual
control of the food supply is largely chemical, and the pure
food laws can be enforced only through chemistry.

Of the many applications of chemistry to medicine, the
problem of immunity in its broadest sense is perhaps one of
the most important, and then we have also the problem re-
garding those diseases which are in the largest sense sys-
temic, — like diabetes, gout, and some of the atrophies, and
even senility itself. It is possible even that the question of
the origin of cancer, one of the few diseases which has thus far
baffled research, and which so far as we know is probably not

86 MORRIS LOEB

of microbic origin, may turn out eventually to be a purely
chemical problem.

The whole domain of hygiene and preventive or state
medicine is a field of investigation which only those well
trained in chemical research can deal with intelligently. A
chemical training is, therefore, an essential part of the educa-
tion of the health officer, who plays so increasingly important
a r61e in the economy of our modern civilization.

It is hardly necessary to maintain at length here the boon
to humanity which such chemical substances as ether, chloro-
form, and cocaine have been, and the important role which
many of the coal tar products have played in pharma-
cology.

The law against arsenic in wall-papers was the result of
a movement which was started from the University Labora-
tory, being put on a scientific basis by Professor Sanger's
proof that arsenical wall-papers were injurious, by analyses
of the urine of patients. The debt which surgery owes to
this University for the part it played in the introduction of
ether as an anesthetic in surgical operations should not be
forgotten.

The structure of many physiologically active substances
has now been made out, and by making allied substances
with similar structure, by an experimental transposition of
molecules in the hands of trained workers, many new and
equally valuable drugs may be obtained. This scientific
search for medicine, which is still in its infancy, is sure of
bringing great results in the future.

Finally, from a purely business point of view, the encourage-
ment of chemical research is of the highest importance. As
competition increases, the successful man will more and more
be the one who lets nothing go to waste, but adopts the most
efficient processes and devises new ones still more efficient;

REPORT ON CHEMICAL LABORATORY 87

who works up his by-products into some useful, and, there-
fore, valuable substances, who economizes energy, whether
k this energy comes from coal or water power, or human labor.
The field is too large and chemical laws too complex to have
the results come accidentally. They can be accomplished only
by a systematic investigation of the whole field of chemistry.
Only upon the study of pure chemistry and the laws which
underlie it, can be built the practice of chemical technology,
just as our whole modern technique of electricity was built
upon the purely scientific experiments of Faraday, or the
modern system of wireless telegraphy was built upon the cal-
culations of Clerk Maxwell, and the scientific experiments of
Hertz. An improvement of a chemical process which betters
the yield by five per cent may mean $10,000,000 a year to a
single large corporation in a time not far distant, if not even
to-day.1 Colossal fortunes have already been made in this
way. It is slowly creeping into the minds of business men
and manufacturers, that a trained chemist can improve an
output or effect economies, and that something more than
a mere analyst is necessary in a manufacturing concern. But
how many persons understand that chemistry is essential
in most plans for the social uplifting of the people?

In Europe it is a truism that well-endowed and active
laboratories of pure chemistry are a source of wealth to the
community, and nothing is more striking than the close co-
operation between the German chemical professors and the
"works-chemists" of the great German chemical industries.
This cooperation it is which has put the German chemical
industry at the head, with no other country a respectable
second. England is fast losing her supremacy in manufac-
turing where chemistry plays a part, and the success of the

1 The gross income of the Steel Corporation in 1907 was $757,000,000; its net
income available for sinking funds, interest, dividends, etc., was $160,000,000.

88 MORRIS LOEB

Germans and the backwardness of the English is to be at-
tributed to the difference of the educational systems of the
two countries, in the large supply of highly educated chemists
in Germany, and the smaller supply and want of their employ-
ment in England. In a very large degree, the commercial
prosperity of the German Empire is dependent upon this
supremacy. The German Emperor himself has said this, and
it is generally believed in German universities. The Badische
Anilin und Soda Fabrik employs more than one hundred
men on pure research, and other corporations in proportion,
not only for purely chemical work, but for the manufacture
of iron and steel, and in other kinds of industry.

There are two chemical plants in Germany, each as big as
the General Electric Company's plant, whose works are so
correlated that the waste products of one serve as the valu-
able products for the other. From one to two hundred doc-
tors of philosophy in chemistry are employed in some of these
great establishments.

The importance of chemistry on the continent of Europe
is attested in a remarkable manner by the expenditures of
the several governments for the equipment and mainte-
nance of the chemical laboratories of their universities and
schools of technology. In Berlin, for example, the cost of a
laboratory built about twelve years ago for Fischer, was
1,316,000 marks, with 64,000 marks more for a connected
dwelling-house for the director. There are in Berlin, in ad-
dition to this laboratory, laboratories of inorganic chemistry
and of physical chemistry for the university, and a fine large
chemical laboratory for the technical school. All these labora-
tories together probably cost a good deal more than 3,000,000
marks.

Strassburg is a university with about one third as many
teachers and students of chemistry as Harvard. The Strass-

REPORT ON CHEMICAL LABORATORY 89

burg laboratory is devoted to organic and inorganic chemistry
exclusively. To build it to-day in Cambridge would cost
about $300,000. Allowing for difference in cost of construc-
tion, either of these cases indicates that the Prussian govern-
ment would, in a case like Harvard's, devote about $1,000,-
000 to the construction of chemical laboratories.

Not less significant are the yearly budgets of some of the
European universities. In Berlin the chemical laboratory
above mentioned has from the government 80,000 marks a
year for running expenses, the physico-chemical laboratory
20,000 marks. These sums are in no part derived from tui-
tion fees, but are direct subsidies. Together with the similar
appropriations for the other chemical laboratories of the uni-
versity and the technical school they certainly exceed 150,000
marks yearly.1

In Berlin the physical laboratory receives 33,000 marks a
year. The university library has 121,000 marks, which is not
more than three fourths the sum devoted to all the chemical
laboratories of the university and the technical school, and
only fifty per cent more than the sum devoted to one of
them.

In Leipsic the three chemical laboratories have 80,000
marks a year for running expenses, the physical laboratory
only about 27,000 marks.

In Strassburg the chemical laboratory has 34,000 marks
a year, the physical laboratory 14,000 marks; the library,
which serves both university and province (Alsace-Lorraine),
has about 72,000 marks. If one assigns one half of this library
budget to the university and one half to the province, it ap-
pears that a chemical laboratory which is dealing with only
two of the important divisions of chemistry and has but one

1 The Harvard laboratory has from the Corporation approximately $900 yearly
for running expenses. Other sources of income are similar in the two countries.

90 MORRIS LOEB

professor ordinarius, and but one professor extraordinarius,
receives nearly as much money as the university library for
running expenses.

In Zurich the university chemical laboratory is voted
f .24,800 a year. This sum is approximately equal to the total
yearly appropriations for the laboratories of physics, bot-
any, zoology, anatomy, physiology, and pathology together
(f. 25,600).

These facts indicate that a German or Swiss government
would, in a case like Harvard's, devote about $25,000 a year
to the maintenance of chemical laboratories. These data,
together with the confirmatory facts, also indicate that in
Germany and Switzerland the chemical laboratories are re-
garded as of equal importance with the university library,
about three times as important as physical laboratories, and
as equalling in importance the institutes of six other sciences
taken together.

Speakers at meetings in America which have any bearing
on chemistry intimate that we are beginning to profit by
this lesson, and are using trained scientific knowledge in ever
increasing proportion, and that the results can be already
seen.

The General Electric Company employs from twenty to
twenty-five physicists and chemists, and the Eastman Kodak
Company, which is highly successful, employs three or four
research chemists. The Pennsylvania Railroad has a large
staff of chemists assisting their research chemist in studying
the qualities of steel.

If we admit as a principle that the funds should be distrib-
uted to each department of the University in due proportion,
then we think that the claims of the Department of Chemistry
should stand very high. Harvard has always been a leader
in university education in this country, and it is still aiming

REPORT ON CHEMICAL LABORATORY 91

strenuously to maintain that position. Is it not wise, there-
fore, in planning the education of her students, to give due
encouragement to the distinguished staff which is now labor-
ing under exceeding difficulties to maintain a well-earned
supremacy in this department?

Is it not advisable that Harvard should recognize the new
movement of industrial chemistry? Should she not be a leader
in this line of research, and come thus in close touch with the
wants of the people by showing them how to make produc-
tion more effective? By following the policy already adopted
by some of the state universities and giving instruction in
agricultural chemistry, it is not too wild a dream to hope that
the abandoned farms of New England may be blossoming
like gardens in the next fifty years.

Your Committee do not, therefore, hesitate to indorse the
plan already outlined by this department. It is estimated
that buildings of the character contemplated can be built for
$500,000; a further sum of $500,000 would be needed for the
proper endowment of such a plan. This is in itself doubtless
a large sum, but small in comparison with amounts expended
on many industrial projects.

Although it may not be possible to carry out this scheme
at once on the scale contemplated, the establishment of a re-
search laboratory as a beginning would be of great benefit,
if the project could be carried out on a consistent plan,
which should be adopted at the outset. The estimates for
such a laboratory have been made, and in round numbers
would amount to about $50,000 for building and installa-
tion. A further sum of $50,000 would be needed for en-
dowment.

The Committee would, therefore, urge strongly that an
attempt be made at once to obtain $100,000 for this pur-
pose, and thus make a beginning of the development of this

92 MORRIS LOEB

department on a scale suited to its needs at the present
time.1

The last century has been a century of mechanical power,
made available by the perfection of machinery and the
development of electricity. The coming century promises to
be a chemical century. Should Harvard, if all this be true,
be content until it has obtained the best chemical laboratory
in the world?

J. COLLINS WARREN,
CLIFFORD RICHARDSON,
JAMES M. CRAFTS,
MORRIS LOEB.

March 27, 1909.

1 Within a month from the date of this report Professor Loeb and his brother
James Loeb generously carried out the Committee's recommendation by offering
$50,000 for the proposed building, provided that other friends of the University
should subscribe an equal sum. The project is now completed, and the research
laboratory, named the Wolcott Gibbs Memorial Laboratory through the suggestion
of Dr. Loeb, is now in full operation. [Editor, April, 1913.]

THE CONDITIONS AFFECTING CHEMISTRY
IN NEW YORK1

IN assuming the chair, I am confident that the coming
year will be one of great progress in our section's history,
not through any merit of its officers, but through the ever-
increasing spirit of cooperation among the members, and the
rapid strides which research and industry are making in this
country. You will hear reports, this evening, of two im-
portant general meetings of interest to our membership,
that of our own society at Detroit and that of the Interna-
tional Congress of Applied Chemistry at London. In both,
members of this section bore a worthy share, and it is a grati-
fying tribute to American progress in science and industry,
that the International Congress chose America for its next
meeting-place. It is not only the foreigner who lands at
Ellis Island that deems America synonymous with New
York, and the members of this section must be prepared to
do their full duty, during the next three years, in order that
our foreign brethren may carry back from their visit a crys-
talline rather than a colloidal vision of chemistry in America.

And so, gentlemen, I have preferred to devote the minutes
which custom permits your chairman to employ in airing his
personal views, to a survey of the conditions affecting chem-
istry in New York, rather than to the presentation of some
debatable scientific ideas, as I had originally intended. The
choice of the more subjective topic is rendered more appro-
priate by the fact that this meeting is to be followed by a

1 Address of the chairman of the New York Section of the American Chemical
Society, delivered October 8, 1909. Reprinted from Science, N. S., 30, No. 776,
pp. 664-£8, November 12, 1909.

94 MORRIS LOEB

session of The Chemists' Club, called for the purpose of
settling a question vitally affecting the interests of New
York chemists.

Eighteen years ago, when the men who had carried the
American Chemical Society through so many vicissitudes
organized this section, in order that the general society
might become a truly national one, I had the honor, rather
than the duty, of being the first local secretary. The meetings
were so poorly attended, the original papers so scarce, and
the general business so unimportant, that no heavy work
devolved upon its officers. We met in the chapel of the old
university building, where Professor Hall and I had our primi-
tive laboratories, out of which we carved, with some difficulty,
shelf -room for the fragmentary society library. When we felt
in need of a little variety, we sat in Professor Chandler's
lecture-room in 49th Street and listened to the passing trains;
or in East 23d Street, peered at the chairman ensconced
behind batteries of Professor Doremus's bell-jars and air-
pumps. An attendance of forty members, I believe, was a
record-breaking event.

I need hardly expatiate upon the wonderful changes that
have been wrought since 1891. Our three colleges have moved
far uptown, and the splendid Havemeyer laboratories of
Columbia and New York University, and the beautiful new
chemistry building on St. Nicholas Terrace, make us glad
to miss the dingy and crowded places where chemistry was
taught an academic generation ago. Our own section and
kindred societies have been meeting in this hall of The Chem-
ists' Club for the past ten seasons, and no one can estimate
what share a fixed and commodious meeting-place has borne
in the marvelous increase in membership and attendance.
The other important factor is, of course, the growth of chem-
ical industry in this vicinity.

CHEMISTRY IN NEW YORK 95

While we can, therefore, congratulate ourselves upon the
great strides that have been made, during the past two dec-
ades, it behooves us to inquire whether there are not still
some drawbacks to our progress, not by way of carping criti-
cism, but for the purpose of seeking such effective remedies
that future progress may be made absolutely certain.

For obvious reasons, we need not ask whether the internal
conditions in the chemical factories are satisfactory; since
there the managers must know that their success depends
upon the scientific abilities of their chemists. It is doubtful
whether the same can be said of the establishments which
employ a chemist or two to apply specific tests; and it is cer-
tain that there are still many factories which conduct, by
rule of thumb, operations that should be continually con-
trolled by scientific tests, if shameful waste is to be avoided.

The American people are but slowly learning the importance
of the educated banker and the expert accountant alongside
the brilliant financier and the bold speculator; similarly,
while they acclaim the clever inventor and the skillful engineer,
they have yet to recognize the worth of that expert account-
ant of material economy, the industrial chemist. Quite aside,
therefore, from any wish for greater profits to our associates
who are gaining their daily bread as commercial or analytical
chemists, patriotic motives lead us to the earnest hope that
closer watch upon the economy of production may bring
about that conservation of natural resources of which the
politicians prate, but for which the chemist works. How, then,
can the status of the independent commercial chemist be
raised in our city? By giving him a central rally-point; a
home that proves to the layman that his is a skilled profes-
sion, not a mere job-hunting trade; a place where the manu-
facturer or merchant can find the man he wants without a
rambling search through the city directory. Doubtless, some

96 MORRIS LOEB

of our colleagues are so well known, that all the business comes
to them which they can handle. But the many additional
independent chemists, whom our commercial situation de-
mands, can only establish themselves if they can secure proper
laboratory facilities, without hiring attics in tumble-down
rookeries.

Every year scores of New Yorkers graduate in chemistry
from our local institutions and return from years of protracted
study in other American and European institutions. They are
enthusiastic for research; in completing their theses they have
laid aside definite ideas for subsequent experimentation;
but they have no laboratory. While waiting to hear from the
teachers' agency where they have registered, while carrying
on desultory correspondence with manufacturers who may
give them a chance, they do not venture upon expenditure
of time and money to fit out a private laboratory, which they
may be called upon to quit any minute upon the appearance
of that desired appointment. Often necessity or tedium will
cause them to accept temporary work of an entirely different
character and indefinitely postpone the execution of the ex-
periments which they had mapped out. Who will estimate
the loss of scientific momentum, the economic and intellec-
tual waste, which this lack of laboratory facilities for the
graduate inflicts upon New York, as compared with Berlin,
Vienna, Paris, and London? Either our universities and
colleges, or private enterprise, should provide temporary
desk-room for the independent research chemist.

So much for the purely practical side of our question.
How about the opportunities for presenting the results of
investigation? We all appreciate the excellence of the three
chemical journals published by our own society, as well as
that of the Society of Chemical Industry, and we may say
that these, together with the independently conducted peri-

CHEMISTRY IN NEW YORK 97

odicals, enable everybody to obtain a hearing; but it does
seem to me that the cost of subscribing to all of these journals
is excessive, and that much unnecessary expense is incurred
through duplication of administrative efforts, as well as
through duplication of abstracts, etc. This, of course, is a
problem with which we, as a local section, are not directly
called upon to deal; nevertheless, it is proper to call the at-
tention of those who are interested in the management of
chemical societies in America to the fact that membership
alone in the various chemical organizations of New York costs
upwards of fifty dollars per year, and that it would be but
fair to so arrange matters that the total cost would be re-
duced by a sort of clubbing arrangement, proportionately
to the number of societies to which a member belongs. It
seems to me, however, that in one particular point we are at
a distinct disadvantage as compared with the foreign chem-
ists: the frequency of regular meetings at which papers can
be presented for the purpose of securing priority of publica-
tion. Would it not be possible for our various local sections,
including the Chemical Section of the New York Academy
of Sciences, to arrange the dates of their meetings conjointly
in such a way that a meeting would occur once a week during
nine months, and once a month during the summer, thus se-
curing for the New York chemist the same opportunities for
the early presentation of a scientific discovery that are pos-
sessed by his brethren in European centres? There is, of
course, another remedy which appeals to me, though I do not
express it with any degree of urgency; namely, the consolida-
tion of all local sections into a single organization which would
affiliate its members automatically with all the national bodies
now in existence, and would turn over the scientific material
of its meetings to those journals for which it seemed most
suited. As a matter of fact, glancing over the annual lists of

98 MORRIS LOEB

our various local organizations, I find a remarkable inter-
changeability of officers, and can hardly imagine that the
interests of their memberships can be very far apart if the
chairman of the New York Section of the American Chemical
Society in one year is the next year expected to guide the for-
tunes of the New York Section of the American Electro-
chemical Society or of the Society of Chemical Industry. If
this were done and we could then exert our influence upon
the various general societies to avoid duplication of work,
by issuing their chemical abstracts jointly, the strain on the
purses as well as the shelves of American chemists would be
greatly relieved.

There is still another point, however, in which the Ameri-
can chemist is at a great disadvantage as compared with the
European: the ease of securing material for his research and
of comparing his results with those of others. In Europe,
especially in Germany, research is never seriously delayed
by lack of a needed preparation, whereas none of our supply
houses carry a full stock of chemicals. To obtain a single
gram of some particular substance, needed for a few pre-
liminary tests, frequently causes weeks of delay, as well as
the disproportionate custom house and brokerage expenses
involved in the importation of small quantities. Besides,
owing to the better centralization of scientific laboratories
in Europe, and the existence in each case of a fairly complete
set of specimens accumulated in the researches of large num-
bers of academic investigators, it is comparatively easy to
obtain by correspondence research material or typical speci-
mens for comparison. In this country, on the other hand, lab-
oratories are scattered throughout the numerous colleges
and universities, and there are no established rules by which
specimens must be deposited with the laboratory. In smaller
laboratories, especially, the chances of preservation after the

CHEMISTRY IN NEW YORK 99

departure of the investigator are not very good. It would be,
consequently, very much more difficult to obtain such speci-
mens here. I would suggest, therefore, that a chemical mu-
seum be established in New York, to perform for the Amer-
ican chemists the functions that the Smithsonian Institution
so admirably carries on for the benefit of American naturalists.
This museum would not attempt to be a popular show-place,
but would embody, in the first place, as complete a collec-
tion as possible of chemically pure materials of the rarer kinds,
so as to supplement, but not in any manner compete with,
the stock of commercial supply-houses. Any scientific in-
vestigator would be entitled to borrow or purchase mate-
rial required for immediate experimentation, and all used
articles would be replaced as quickly as possible.1

In the second place, it would be the depository for speci-
mens of new substances obtained in American research.
Every chemist would be invited to send to the museum a
small quantity of each substance newly prepared by him, not,
indeed, as an evidence of the good faith of his investigation,
but, rather, to enable future workers to obtain such material,
either for comparison, or for further experimentation with
the least possible delay. Many substances that are now car-
ried away from universities by students who subsequently
abandon chemical research, or which belong to the families
of deceased chemists who do not know what to do with them,
would thereby be rescued from oblivion, and might ultimately
become of the greatest value for a special purpose.

Thirdly, this museum would invite chemical manufacturers
to send standard samples of their products, and thereby facili-
tate the commercial relations between consumer and manu-
facturer.

To such a museum there could be attached a competent

1 A museum of this kind was provided for in Dr. Loeb's will. [EDITOR.]

100 MORRIS LOEB

staff of workers for the preparation of samples not other-
wise available. In the analysis of samples submitted as offi-
cial standards, we should have the beginning of that Che-
mische Reichsanstalt which is now the chief object to which
German chemists are directing their attention.

The past twenty years have seen the construction of in-
numerable teaching laboratories in our vicinity. They have
seen an undreamt-of development and growth of chemical
industry, and, above all, they have seen the coming together
of the scattered chemists into a large and powerful society.
Now is the time when we should make every effort to direct
these forces that we have marshaled toward the attainment
of definite objects, and coordinate all our enterprises in those
directions that will make for the improvement of the intel-
lectual as well as the material conditions of our beloved city.

SIR ISAAC NEWTON1

WE celebrate so frequently the heroic deeds of warriors
that it may be a welcome change to spend a short hour in the
consideration of a great man whose renown depends entirely
upon peaceful victories. Isaac Newton was a farmer's son,
who lived a quiet life of eighty-five years almost entirely unaf-
fected by the events of the world about him, but who left,
nevertheless, monuments as important as those which com-
memorate any victory on land or sea. He fought and con-
quered ignorance and error; he established new laws of
thought; he discovered for us new beauties in nature; and he
opened before our eyes the harmonies of light that are as
wonderful and as elevating as the harmonies of music. Un-
selfish and regardless of worldly gain, he succeeded in add-
ing untold wealth and comfort to our common store. Mathe-
matics, astronomy, navigation and mechanics all owe a mighty
debt to this quiet student; and in Westminster Abbey his
monument is well placed among England's hereos of thought
and action.

Sir Isaac Newton's name means something to every one
of us; but I doubt whether the majority of this audience
would be able to indicate exactly his claims to fame, and you
may be glad to have some of them pointed out.

He was born at Woolsthorpe, in Lincolnshire, on Decem-
ber 26, 1642, — the year of Galileo's death. His father, Isaac,
he never knew, and he was brought up by his mother, Han-
nah Ayscough, and her brother. He was educated at Gran-

1 There is no clue on the manuscript as to where this lecture was delivered. It
was evidently intended for a popular audience having little knowledge of science.
Marginal notes show that it was illustrated by experiments and lantern slides.

[EDITOR.]

102 MORRIS LOEB

tham Grammar School, and in 1657 he returned to his
mother's farm; but he cannot have been a very successful
farmer, since he was described as a very dreamy boy, and al-
ways prone to study. Four years afterwards, by his uncle's
advice, he entered Trinity College, Cambridge, and very soon
made his mark as a mathematician. It was just at this time
that a great advance inaugurated by Descartes, the applica-
tion of algebra to geometrical calculations, was arousing the
interest of mathematicians. Stimulated by this, young New-
ton developed a still grander advance by the discovery of the
method of infinitesimals.

His study at Trinity College was interrupted in 1665 by the
appearance of the plague in Cambridge, and he took refuge
at Woolsthorpe. A somewhat doubtful but well known
legend reports that here, in the summer of 1666, while he was
lying under an appletree and ruminating upon some mathe-
matical question, a falling apple drew his attention to those
phenomena which he later elucidated through his law of
gravitation.

In 1667 he returned to Cambridge as one of the governing
board of his college, and two years later, at the age of twenty-
six, he became Lucasian Professor of Mathematics, and lec-
tured chiefly on optics, in which branch of physics he made
some of his most remarkable discoveries. From that time
on his life was a continuation of successes. In 1672 he was
elected to the newly founded Royal Society, practically the
oldest society for scientific research in the world, of which he
became President in 1703. In 1687 he published his magnum
opus, entitled " Philosophise Naturalis Principia Mathemat-
ical He was elected to Parliament in 1689, and served for
many years. In 1694 he was appointed Warden of the Mint,
and in 1697 Master of the Mint; and since his time it has
been the custom to entrust the British Mint to some master of

SIR ISAAC NEWTON 103

physical science. As a result I believe that the London Mint
has always been foremost in the application of scientific pro-
cesses to the problem of securing permanent and stable coin
for the realm.

In 1705 Isaac Newton was knighted by Queen Anne, and
in 1727, on March 20, laden with all the honors which his
country could bestow upon him, he died peacefully, mourned
by all, hated by none. He was buried with all honors in West-
minster Abbey, and a fitting monument was erected over
his grave.

His character is said to have been of the kindliest, and all
contemporaneous records speak of his amiability. A patient
student, a keen observer of nature, and a brilliant inventor,
he stands out through his work as one of the greatest scien-
tific men of all time. His great services to mankind embraced
discoveries in mathematics, astronomy, and physics. Perhaps
his mathematical work ought to be considered the most im-
portant, for it might be considered to be at the root of all our
scientific knowledge, and yet I despair of explaining to you
in what these mathematical discoveries consisted. Up to
his time it was only possible to calculate with quantities that
were not supposed to change during the calculations. He
showed us how to work with quantities that varied. Before
him it was necessary to imagine bodies to be at rest before
their relations could be ascertained; he showed how to deal
with moving bodies. His invention " Fluxions" (now called
the " Differential Calculus") was for the mathematician what
the Rontgen discovery is for the physician. The fact that
Leibnitz almost at the same time independently made the
same discovery, does not detract from Newton's merit.

Having devised this great improvement in calculating he
began to see clearly things that Copernicus, Kepler, and
Galileo had vainly attempted to comprehend. Perhaps the

104 MORRIS LOEB

earlier investigators had actually understood these things
in part, but not clearly enough to explain them to others.
For example, there were several ideas of Galileo's about mo-
tion which Newton has made so clear to us that we now call
them Newton's Laws, namely:

First Law: If no force acts upon a body in motion it con-
tinues to move uniformly in a straight line. Formerly men
imagined that a body must be continuously pushed to keep
it moving. Now we know that force is needed to stop it.
Ordinarily the force applied is friction, but if a body moves
with little friction over a smooth surface, as in skating, a
single push causes it to travel a long distance.

Second Law: If force acts on a body it produces a change
of motion proportional to the force and in the same direction.

Third Law: When a body exerts force upon another body
it experiences an equivalent reaction from the latter.

The results of these laws were long known, but the prin-
ciple was not understood. When David killed Goliath, as we
read in the Bible, he shot a little stone at him from a sling.
He knew that if he swung the sling around, the pebble would
be held back by the sling that only allowed it to go a certain
distance from his hand, but as soon as it was released it did
not fly in a circle, but in a straight line. Here we have New-
ton's first law; and the sling represented the force which
caused the pebble to apply the second law and change its
direction.

Again, the fact of gravitation was known long before New-
ton studied it. Many an object must have fallen upon a
philosopher's head before Newton was aroused by his mythical
apple, and we have experiments by Galileo that showed a
pretty clear notion of the law of gravitation as regards terres-
trial objects. That all objects are attracted equally to the
earth cannot be shown unless we remove obstructions from

SIR ISAAC NEWTON 105

their path. The buoyancy of the air will affect light masses
more than dense ones; if the air be removed all substances will
fall to earth with equal rapidity. Newton's great step was the
extension of the idea of gravitation to celestial objects; and
he claimed that all masses attract each other at all times, but
that distance influences the intensity of this attraction.

By means of Newton's generalization astronomers have been
able to calculate the mutual attraction of the various planets
for each other and for the sun. The more closely celestial
bodies approach one another, the more they affect each
other's motions; with the help of Newton's law these irregu-
larities in the orbits have been explained. The matter has
been carried even further; from such perturbations of Saturn,
Leverrier was able to predict the existence of the then un-
known planet Neptune, and to tell owners of better tele-
scopes than he possessed where to look for it.

Again, Newton was the first to explain the tides, and to
show how they were due to the action of the moon and the
sun upon the ocean, although the larger body, the sun, is so
much farther from the earth than is the moon that its attrac-
tion is less apparent. The moon appears to revolve around the
earth once in about twenty-four and one half hours, whereas
the average interval between the successive appearances
of the sun is twenty-four hours. The solar tide and lunar tide
therefore pursue unequal rates. On the occasions when they
come together we have the high or spring tides. When they
oppose each other we have the low or neap tides.

More practical still were Newton's discoveries in optics.
Telescopes had been made by Galileo and others before
him, but the lenses employed were imperfect owing to the
difficulties in the manufacture of glass, and the light in pass-
ing through them showed queer colorations. The images
were blurred and surrounded by colored fringes. It is only

106 MORRIS LOEB

in recent days that all these imperfections have been cor-
rected, and we now have glass lenses of forty inches' diameter,
as in the great Chicago telescope. But Newton invented a
telescope which was quite independent of glasses, using the
principle which you can discover for yourselves by looking
into the bowl of an ordinary tablespoon. The reflecting
telescope has been much used, and the highest point reached
in its construction was Lord Rosse's instrument, which was
fifty feet long, six feet in diameter, and possessed a mirror
weighing six tons.

Yet another practical device comes even more closely
home to us. Navigators are indebted to Newton for the in-
strument next in importance to the compass, — the sextant.

The chromatic errors of lenses led Newton to study the
nature of light so profoundly that he not only avoided the
errors of his predecessors but also profited by them. Allowing
a beam of sunlight to pass through the round hole of a shutter
and fall upon a prism, he found that it was broken up, and
that in place of a single white dot it became a streak of various
colors. From this he inferred that white light is not simple but
consists of various rays that can be separated by a prism. He
attempted to recompose the light out of the colors into which
he had dissociated it, and found here again that he was suc-
cessful. From this discovery of Newton's there have been
distinct advances in later times. It is found better to re-
place the round hole in the shutter by a slit. We then find
that white light is decomposed to give a band of purer
colors than that obtained through a round opening. It is
called a spectrum, and is well known to most of you. This
band can be shown to be made of little images of the slit
placed side by side. Afterwards Fraunhofer showed that if
the slit was made narrow enough, a large number of fine lines
appeared across the spectrum. And later still, Bunsen and

SIR ISAAC NEWTON 107

Kirchhoff showed, first, that each chemical element emits
certain rays having fixed places in the spectrum, and sec-
ondly, that many elements emit rays that coincide in their
position with the lines discovered by Fraunhofer in the solar
spectrum. From these coincidences we are enabled to assert
positive knowledge as to the chemical constitution of the sun
and other heavenly bodies far beyond the reach of any other
known method of analysis.

Thus Newton seems by his magic touch to have opened
doors to mysterious chambers in nature's mansion, some
destined to become workshops for man's practical needs,
some treasuries of his mental wealth. Well did he deserve
the eulogy of the poet Pope: —

" Nature and nature's laws lay hid in night,
God said, ' Let Newton be,' and all was light!"

OLIVER WOLCOTT GIBBS1

WHEN Oliver Wolcott Gibbs died, on December 9th, 1908,
American chemists were bereft of one of their leaders,
to whom they could look, with affectionate respect, as a
pioneer in research, and the true example of the tireless seeker
after truth, withal an earnest patriot and a noble gentleman.
He was never at the head of a great university laboratory,
and the last twenty-five years of his life were spent in retire-
ment from all academic duties; no great body of students
is left to mourn the loss of their former teacher. He wrote
comparatively few papers of general interest and no books;
he shrank instinctively from appearing in the public eye,
and the idea of making even an informal after-dinner speech
was hateful to him. His austere demeanor and dignified re-
serve must have always prevented his gaining popularity
with the masses, even if his tastes had not led him to prefer
scholarly seclusion. To what, then, shall we ascribe the
influence which he wielded in the world of chemistry, so that
foreign as well as American institutions of learning delighted
in showering honors upon him, and considered themselves
fortunate if they could obtain his cooperation and advice ?
Was it not because we all realized that this was a true High-
Priest of knowledge, a guardian of the sanctuary, rather than
an exploiter of its mysteries; one who could read without an
accusing pang, that beautiful distich in which Schiller says
of Science : —

" Einem ist sie die hohe, die himmlische Gottin, dem Andern
Eine tiichtige Kuh, die ihn mit Butter versorgt."

1 Reprinted from Proceedings, Am. Chem. Soc. (1910), p. 69.

OLIVER WOLCOTT GIBBS 109

Gibbs, a man of modest wants, was probably always pos-
sessed of such means that he could restrict himself to the aca-
demic side of his profession, and his family traditions and
early training would hardly have fitted him for business. I
remember conversations with him about the successful ca-
reers of his friends, A. W. Hofmann and Joseph Wharton,
which made it clear that he would not have attacked a tech-
nical problem with any degree of confidence. Perhaps, there-
fore, a knowledge of his own limitations may have assisted
his natural predilections in determining the direction of his
work toward pure, one may almost say abstruse, science.
But his contemporaries saw a man seeking truth for truth's
sake, and they put their trust in his disinterestedness, as
well as in his scientific acumen and experimental skill. Justly
conscious of his own worth, he was quick to recognize what
was meritorious in the work of others, and to applaud, without
reserve, the advances along lines quite foreign to his own point
of view, while maintaining an almost pathetic veneration
for his own great masters, between whom and the present
generation he remained one of the last links. Cant, religious,
moral or scientific, was abhorrent to him, and he could be
cruelly caustic in his denunciation of what he deemed charla-
tanry or insincerity. On the other hand, where he once placed
his trust, he left it implicitly, and, when his advice and help
were sought, in good faith, he gave of his best. In appearance,
and in some respect manners, he resembled James Russell
Lowell, to whom I believe he was distantly related. It would
have taken considerable boldness to be flippant in his presence,
and his students, at all periods of his life, seem to have stood
in great awe of him. But he was dearly beloved by friends
in and out of academic circles, and he seemed to have the
power of impressing his own enthusiasm upon those with
whom he collaborated for the public good, as well as for the

110 MORRIS LOEB

advancement of science. The Union League and Century
Clubs, of New York City, owe their foundation largely to his
efforts, just as did the National Academy of Science in Wash-
ington; his effectiveness as a member of theU. S. Sanitary
Commission, during the Civil War, seemed to have exacted
the lifelong respect of all his associates.

While, therefore, it was an inestimable gain to the Law-
rence Scientific School to secure this master of research, one
cannot help wondering whether the narrowness which kept
him out of his own alma mater, and forced him to leave the
city of his birth, did not curtail some of his most useful powers.
Furthermore, the policy which subsequent events have proved
thoroughly mistaken, of reducing the Lawrence Scientific
School in 1871 from its status as virtually a graduate faculty
of natural and exact science, to a shadowy existence as an
appendage of Harvard College, deprived Professor Gibbs
of his teaching laboratory, and barred American students of
chemistry from working under the direction of a guide who
remained for another quarter of a century the master of in-
organic research. In fact, during less than eight years of
his entire career was he in a position to assign topics for
independent research to students in his laboratory, and thus
carry out those parallel tests which are the great resource of
the modern university professor. Thus it is that the figure
of Wolcott Gibbs, even though so recently faded from our
eyes, towers in our memory like that of one of the early
frontiersmen blazing out new paths in a primeval forest;
like the heroes of James Fenimore Cooper, who seek the
wilderness from love of nature, not from hatred of man, and
who are solitary, not from a saturnine disposition, but from
lack of followers willing to forsake easy harvest for the chances
of a laborious chase.

But to those who were his immediate contemporaries,

OLIVER WOLCOTT GIBBS 111

Gibbs could not have appeared as a recluse. In the "Ameri-
can Journal of Science," he was for twenty-two years the
eloquent interpreter of the trend of chemistry to workers
in other fields of science, and, similarly, the early volumes of
the "Berichte der deutschen chemischen Gesellschaft" con-
tain his concise but adequate reports of the achievements
of American chemistry. His understanding and sympathy
for other branches of exact sciences was great, and, in fact,
thermodynamics and optics received much of his attention:
he it was who first appreciated the work of his namesake,
J. Willard Gibbs, and insisted on the award of the Rumford
Medal for that treatise on "Equilibrium in Heterogeneous
Systems," which became famous twenty years later, when
Le Chatelier rediscovered it for the benefit of modern chem-
ists. I could instance, from personal observation, other
judgments rendered by him on scientific matters of less mo-
ment, in which the clearness of his vision and the thoroughness
of his examination proved that no accidental circumstances
led him thus to anticipate the trend of physical thought.
His contemporaries were stimulated both by the ideas which
he freely placed at their disposal, and by the appreciative
discrimination which he exercised toward their own scientific
efforts.

Born in New York City, on February 21, 1821, as the second
son of Colonel George and of Laura Gibbs, he was named
after his maternal grandfather, Oliver Wolcott, Secretary of
the Treasury under Washington and Adams. His boyhood
was chiefly spent on his father's farm at Newtown (near
what is now Astoria), Long Island, and he was educated at
the Columbia Grammar School and Columbia College, from
which he received the degrees of A.B. in 1841 and A.M. in
1844. He also graduated in medicine from the College of
Physicians and Surgeons in 1845, though he never practiced

MORRIS LOEB

as a physician. His taste for physics and chemistry developed
early; he published one or two papers as an undergraduate,
worked with Dr. Robert Hare in Philadelphia in 1842, and
went abroad in 1845 to specialize in chemistry, under Ram-
melsberg and Heinrich Rose in Berlin, and under Laurent,
Dumas, and Regnault in Paris. Returning in 1848, he lec-
tured at Delaware College and the College of Physicians and
Surgeons, and was appointed Professor of Physics and Chem-
istry at the Free Academy of New York City, now the Col-
lege of the City of New York, but then practically of high
school grade. Here he taught, chiefly by lectures and reci-
tations, until 1863, when he was called to Harvard to fill
the Rumford Professorship on the Application of Science
to the Useful Arts, then recently vacated by Eben Horsford.
Attached to this professorship was the Chemical Laboratory
of the Lawrence Scientific School, but this was consolidated
with the College Laboratory in 1871, under Professor J. P.
Cooke, and Professor Gibbs thereafter limited himself to
courses in Physical Chemistry, continuing his chemical in-
vestigations with the aid of paid assistants.

In 1887, he was made Professor Emeritus, and retired to
Newport, Rhode Island, where he had always spent his sum-
mers on property long in the possession of his family. Here
he built a small laboratory, overlooking the beach, in which
he continued to work for another decade, until his waning
strength warned him to desist. He had lost his dearly loved
wife, Josephine Mauran, shortly before his retirement from
Cambridge, and he lived very quietly at Newport, attended
by a devoted niece, interesting himself chiefly in horticulture
as a pastime. He had little taste for the fine arts, but was
passionately fond of nature and a friend of all living things.
I vividly remember his indignation, one day, when, in the
course of a walk, we came across a contractor who was pre-

OLIVER WOLCOTT GIBBS 113

paring to lop off from a beautiful old tree a great branch that
extended into a street through which he wished to move the
villa of a summer resident. When the man refused to listen
to remonstrances, I was left to guard the tree, while the Doc-
tor set off to find a policeman and finally routed out the
Mayor of Newport, with the result that the house had a
quarter mile more to travel and the tree was saved.

I have already stated that Gibbs's opportunity to teach
advanced chemistry to students was limited to eight years:
Professor F. W. Clarke has given an authoritative account
of his teaching at this period, in his beautiful lecture before
the Chemical Society of London.1 My own experience came
later, when I fortunately joined the very small class which
attended the course in Chemical Physics to which he confined
himself after 1871. The formal part of the lesson was fre-
quently dismissed in a few minutes, in which he handed out
his full lecture notes, to be copied at home: the remainder
of the hour was devoted to experimentation or to purely in-
formal discussion of problems arising out of the general topic.
I do not think that the subject was ever treated exhaustively,
but we all felt enriched and stimulated when the hour was
over. Unfortunately, the course was not correlated to any
other work in the University, and I doubt whether, at any
one time, more than a dozen undergraduates knew Professor
Gibbs by sight.

Privileged, half a dozen years later, to assist him at his pri-
vate research laboratory, in Newport, I was able to observe
more closely his methods of thought and work. He belonged
emphatically to what might be termed the Berzelius type of
chemist, basing his views upon an intimate knowledge of the
reactions of a selected number of elements, and preferring
direct deduction from qualitative or quantitative evidence

1 Journ. Chem. Soc. Trans. 95, 1299 (1909).

114 MORRIS LOEB

to the experimental substantiation of a hypothesis reached by
inductive speculation. His synthetic researches were chiefly
carried out in test tubes, without overexact measurements
of reacting quantities, of temperature or other conditions.
The elaborate search for an optimum production of a given
compound, so familiar in recent inorganic work, did not ap-
peal to him, and he frequently emphasized his desire to point
out the directions in which complex compounds should be
sought, leaving their careful study to others. Working with
the simplest apparatus, almost exclusively in aqueous solu-
tions, he certainly produced an astonishing number of new
compounds, whose correlations he was able to point out with
considerable verisimilitude. Perhaps he missed a reaction
here and there; but few of his critics have been able to state
that they failed to find what he did, when they followed his
directions closely. As an analyst, he enriched us with some
elegant methods, which are not sufficiently emphasized in
textbooks: the determination of manganese as pyrophos-
phate; the use of mercuric oxide instead of a fixed alkali in
precipitating various acids with mercuric nitrate; improve-
ments in the estimation of bases as sulphates and oxalates;
the detection of cerium by means of bismuth tetroxide or
lead peroxide; the use of luteocobalt salts to characterize
various acids. The determination of metals by electrolysis,
the operation of difficult fusions downward instead of upward,
the use of a comparison tube in eudiometric measurements,
were all methods first published by him, and many methods
developed by others were due to his suggestions. In physics,
he early remedied defects in some types of galvanic cell, now
obsolete, and he devised improvements of considerable value
in the prism spectroscope.

A curious departure from his customary work was his
reversion, late in life, to physiological chemistry, when he

OLIVER WOLCOTT GIBBS 115

undertook in 1889 with H. A. Hare and later with E. T.
Reichert the systematic study of the action of definitely re-
lated organic compounds upon animals. His ideal was the
establishment of principles whereby the physiological effect
of drugs might be enhanced or modified step by step, so as to
produce gradations of physiological effect comparable to the
shading of the spectral colors. The experimental work was
done by his associates, and did not progress far enough to
lead to definite conclusions upon this idea.

The name of Gibbs will, however, be chiefly associated
with his three great researches on the cobalt-ammines, the
platinum metals and the complex acids. The oxidation of
cobalt in ammoniacal solutions had been observed by Gmelin
as early as 1822; but F. A. Genth first produced well-defined
salts of an ammonia-cobalt base in 1847, publishing his results
in 1851, in which latter year papers were published in France
by Claudet and by Fremy, who defined four distinct series.
Gibbs discovered xanthocobalt in 1852, and thereupon asso-
ciated himself with Professor Genth, then at the University
of Pennsylvania, in a thoroughly systematic study, to which
Gibbs seems to have contributed the greater portion of the
experimental detail. The results were published by the
Smithsonian Institution in December, 1856; but the second
series of the work was presented by Gibbs alone to the Ameri-
can Academy of Arts and Sciences in 1874 and 1875. These
papers are noteworthy for the thoroughness with which
each of the many series was studied, analytically as well as
synthetically; he not only showed that the same type of
cobalt-ammine could persist through various combinations
with different acids, but also proved that certain acid groups,
like NO2, must be frequently considered an integral part of
the base, and that this was notably true of the water, con-
sidered by others mere crystal- water, which distinguished the

116 MORRIS LOEB

composition of the roseo- from the purpureo-cobalts. His re-
searches were the natural foundation of Werner's theory,
which has gained general recognition during the past fifteen
years.

Analogy to cobalt-ammines appeared to exist in a com-
pound obtained by Fremy in 1844, by the action of ammoni-
um chloride upon potassium osmiate, and Gibbs proved this,
in a brief note published with Genth in 1857, by showing
that chlorine could be replaced by other negative radicals
without altering the Os : NHs ratio. In his final paper, in
1881, he named these compounds the osmyl-tetrammine
series. But he was deflected from the continued study of the
ammines of the platinum group, which he had evidently pro-
posed to himself in 1858, by the interest which the separa-
tion and complete characterization of these metals them-
selves had excited. Working chiefly with refractory California
ores, he found it necessary to develop new methods of attack,
and his work may well be placed by the side of that of
Claus and St. Clair-Deville.

Meanwhile, the platino-ammines were fully studied by
other observers, and Gibbs rather devoted his attention to the
behavior of the platinum group to acids. In 1877 he found that
the oxides of these metals would unite with the tungstates, to
form the salts of complex acids, analogous to the silico-tung-
states of Marignac, and this was the starting-point for his
great researches on the complex acids, which virtually mo-
nopolized the remainder of his experimental activity. Begin-
ning with attempts at systematizing the straggling data on
silico-tungstates, phospho-tungstates, etc., recorded by other
observers, through the preparation of parallel compounds, he
was led to draw one element after another into the compli-
cated molecules that gather around the tungstic or molybdic
nucleus. With a large corps of assistants at his disposal, the

OLIVER WOLCOTT GIBBS 117

work would have assumed gigantic dimensions; but, with a
single assistant to carry out the most subtile quantitative sep-
arations, his theories must, perforce, await mathematical con-
firmation, and his cabinet must contain scores of unanalyzed
compounds. I believe that he regarded the tungstic acids
more or less as the inorganic analogues of hydrocarbons, with
certain typical arrangements, into which other groups could
enter by direct substitution, largely merging their own iden-
tity. Probably, the majority of modern investigators ascribe
a more important r61e to these elements of lesser atomic
mass; but viewed from the standpoint which I have indicated,
the work of Gibbs will show a remarkable consistency, just
as his experimental data will, undoubtedly, be confirmed in
all essentials by the work of his successors.

And thus the American Chemical Society may well inscribe
among its immortals the name of an honorary member, with
the words of one of his favorite authors: —

"Wer es den Besten seiner Zeit hat gleich gethan
Der hat gelebt fur alle Zeiten."

THE CHEMISTS' CLUB, NEW YORK1

THE Club occupies the lower portion of the new Chemists'
Building, at 50-54 East 41st Street, completed in March,
1911. This building occupies a lot 56 feet by 100 feet, in the
immediate vicinity of the Public Library and the Grand
Central Station. It is owned by a stock company whose
shareholders are chemists, manufacturers and companies em-
ploying chemical processes, and it is to be conducted for the
furtherance of chemical industry and research: in certain
eventualities, The Chemists' Club can acquire ownership of
the building.2 The five uppermost stories — not controlled
by the Club — are constructed for chemical laboratories.

The Club's quarters may be described as follows: The ves-
tibule opens into a large oak-paneled entrance-hall, one side
of which serves as an office, the other as a lounging-room;
a wide corridor leads thence to the main stairway and to the
auditorium, which occupies the entire rear half of the lot.
This auditorium seats 300 persons and has a lecture plat-
form completely equipped for scientific demonstrations : it is
decorated in classic style, and is a very lofty and well-pro-
portioned room.

The upper floors of the Club House are reached by a very
beautiful stairway, quite independent of the public stairway
and elevators. The first landing leads to the auditorium bal-
cony and also to the lavatories. Then comes the first, or social,
floor, the front half of which, a mahogany room 52 by 23 feet,
is furnished for general social purposes; in the rear is the

1 Reprinted from the Year Book of the Club for 1910-11.

2 Dr. Loeb himself was the largest shareholder, and in his will left his holdings
to the Chemists' Building Company for cancellation, thus very materially reducing
the amount of stock to be acquired by the Club. [EDITOR.]

THE CHEMISTS' BUILDING,
52 EAST FORTY-FIRST STREET, NEW YORK

THE CHEMISTS' CLUB, NEW YORK 119

restaurant, with a roof -garden for summer use. The adja-
cent spacious pantry is connected by dumb-waiters with the
kitchen and supply-rooms that are situated in the basement.
For Club banquets the entire floor-space is available. The
second story is known as the Scientific Floor : it is exception-
ally lofty, to accommodate a gallery in the Library, which
has the same dimensions as the social room, immediately
below, and whose shelves can hold upwards of 16,000 volumes,
with additional space in reserve. This room is named Chand-
ler Hall, after the first president of the Club, and it will prove
an ideal work-room for the scientific student. The rear half
of this floor is to be used as a scientific museum, according
to a plan devised by a committee of the American Chemical
Society, but not yet fully developed. Out of it there opens
the board-room, which, in conformity to the character of the
museum, has been designed in imitation of an alchemist's
laboratory and adapted to the preservation of specimens of
old chemical apparatus. A small photographic dark-room
and storage for unbound pamphlets are likewise to be found
on this floor.

The fourth and fifth stories are residential, and provided
with rooms for either transient or permanent occupancy.
There are two suites, consisting of sitting-room, bedroom and
bath-room, with a private corridor, and eighteen other bed-
rooms, a number of which are provided with private bath-
rooms. Each suite or room is named after a college or uni-
versity, whose alumni have furnished it, and this serves to
accentuate the academic spirit of the Club membership. The
institutions thus commemorated are : Harvard, Yale, Prince-
ton, Columbia, Pennsylvania, New York University, Massa-
chusetts Institute of Technology, German Universities,
Cornell, British Schools and Universities, Johns Hopkins,
University of Virginia, University of Michigan, The College

120 MORRIS LOEB

of the City of New York, Imperial University of Japan, Swiss
Universities, Western Universities.

All the floors are connected by telephone with the central
switch-board on the entrance floor, and the same board
serves the tenants of the laboratories in the upper stories.

It is also interesting to note that the Club controls three
small laboratories, named in memory of Wolcott Gibbs,
Robert Bunsen and August W. v. Hofmann, which are
equipped for the transient use of Club members.1 Applica-
tions for their use must be made at the Club office.

1 To these the Chemists' Club has added a fourth memorial, consisting of the
two rooms which constituted Dr. Loeb's laboratory. This is known as the
Morris Loeb Laboratory. [EDITOR.]

THE CHEMISTS' BUILDING1

THE opening of the new Chemists' Building in New York
City is an event of national, rather than merely local signi-
ficance, and the committee in charge has done its duty by
seeking to express this fact in the programme of the opening
exercises. The social comforts of The Chemists' Club are but
an incident in the general scheme, and, in fact, the physical
transfer of that organization from its present quarters to the
splendid home now provided for it must, necessarily, await
the completion of its furnishings, after the building itself was
declared ready for occupancy. Hence, the Club's festivities
were subordinated to the dedication ceremonies of the build-
ing, when due emphasis could be laid upon the serious aims
of the enterprise, and to the scientific meetings, under the
auspices of the local sections of our Society, the American
Electrochemical Society and the Society of Chemical Indus-
try. It will not be the fault of the speakers at these meetings,
if the general public fails to grasp the importance of chemis-
try in our industrial development, and also as a branch of
pure science. We ourselves, and, especially, those of us who
do not dwell in New York itself, or its immediate vicinity,
might well take this occasion to reflect upon the practical
significance of this undertaking.

Nobody can review the history of American progress dur-
ing the past twenty-five years without recognizing how much
more intimately chemistry is enmeshed in the general econo-
mic and sociological texture than a quarter century ago.
Then, the American student who went beyond the general
chemical courses prescribed for all freshmen and sopho-

1 Editorial, reprinted from Journ. Ind. and Eng. Chem., 3, 205 (1911).

MORRIS LOEB

mores did so as a preparation for medicine or some other
recognized profession, or with the definite purpose of entering
an academic career. The possibility of establishing himself as
an independent chemical analyst or expert was certainly
never placed before the student; and the works-chemist, in
the eyes of the industrial world, was held in the sort of regard
which may be likened to Lincoln's estimate of the value of
brigadier-generals, when he remarked, on hearing that a
Confederate raider had cut out a baggage train and captured
three generals, "I can make a brigadier any day, but mules
cost money." Under such conditions, chemistry as a profes-
sion could have slight standing, and the gregarious needs
of its votaries were amply met by the annual " meetings "
of Section C of the American Association for the Advance-
ment of Science, and by occasional local gatherings. The
reorganization of the American Chemical Society on a na-
tional basis, in June, 1890, presaged the change which seems
to have followed the World's Fair at Chicago. We need not
inquire too closely whether the lean years following the finan-
cial crisis of 1893 caused manufacturers to appreciate more
fully the value of chemical control of their processes, or
whether the exhibits of German and other foreign manufac-
turers, coupled with the demonstration of the World's Chem-
ical Congress, attracted the attention of the American public
to the possibilities of the development of a true chemical
industry. Whatever share these or other influences may have
borne, the result may be strikingly shown in a circumstance
connected with the opening ceremonies of the Chemists'
Building. In the preface to Volume xn of the "Journal of
the American Chemical Society," the editor estimated the
number of chemists available for the newly-formed New York
Section at two hundred; twenty-one years later, with dupli-
cates eliminated, thirteen hundred invitations were sent out

THE CHEMISTS' BUILDING

to the enrolled members of the New York local sections of
the three large chemical societies.

Of course, in this phenomenal development of the chemical
profession, America is merely catching up with European
progress, not leading it. The enormous attendance at the
recent Triennial Congress of Applied Chemistry was well
calculated to astonish the non-chemical world; and if the ini-
tiative taken at Chicago in 1893 toward convening these con-
gresses is to our credit, the contrast between the two hundred
and fifty men then in attendance and the chemists who will
crowd New York in October, 1912, will convince America not
only that progress has been made, but also that still greater
advances must be accomplished here, to keep pace with chem-
ical industry abroad. The American Chemical Society would
not fulfil its duty toward its membership by holding occasional
meetings and publishing the proceedings thereof; it must af-
ford them a means for the prompt publication of their re-
searches, as well as for their information upon the world's
progress in pure as well as applied science; its journals must be
the link which binds the isolated worker to his profession.
But there are still other needs; the relations of the profes-
sional chemist toward the industries must be established on a
sounder basis; the elimination of wasteful methods of manu-
facture through chemical control must be advocated more
forcibly and pervasively; chemical industry must cooperate
more closely toward the furthering of mutual interests, toward
the establishment of more satisfactory manufacturing con-
ditions, from the legal, as well as from the hygienic and eco-
nomic aspect; aids must be devised for the furtherance of
research, along'industrial as well as purely scientific lines.

All of these ideas have been expressed atone time or another
by the promoters of the American Chemical Society, and they
were also in the minds of the founders of The Chemists' Club

124 MORRIS LOEB

of New York, which for the past twelve years has maintained,
at considerable pecuniary sacrifice on the part of its mem-
bers, an organization in which the social features were in-
finitesimal as compared with the furtherance of the above-
named objects. The new Chemists' Building represents the
concrete embodiment of these ideals, and the participants
in the Eighth International Congress will find established in
New York City the first building devoted to the furtherance
of chemical science and industry by all those means which
are not distinctly pedagogical. This is a somewhat bold
assertion, but it will bear analysis.

It is needless to descant upon the advantages to be derived
from a well-equipped social club, which affords an attrac-
tive gathering-point for the local chemist, as well as housing
accommodations for the non-resident member. But it might
be well to bear in mind that the industrial chemist usually
visits New York for professional consultation, or for the dis-
cussion of important business propositions; the technical
library is an indispensable tool which he can now employ
without quitting his shelter. Indeed, if a problem arises
suddenly that requires experimental test, the laboratory in
which to try it can be obtained with no more formality than
that needed for engaging a bedroom. For quite a number of
years, The Chemists' Club has made it an object to promote
the interests of young chemists, as well as those of the manu-
facturer, by maintaining a professional employment bureau,
which was chiefly hampered by the lack of a permanent
office. Could this not be established in the new Club-house
in such a manner as greatly to facilitate the establishment of
communication between the dispenser and seeker of employ-
ment?

The existence of a complete building, devoted solely to the
interests of the chemists, will probably be the best demon-

THE CHEMISTS' BUILDING 125

stration to the American public of the importance which this
profession has now assumed from the technical standpoint.
The consulting chemist, housed in laboratories for his own
use, can well expect greater consideration than the man who is
obliged to conduct his work in a ramshackle rookery, or, at
best, in an out-of-the-way corner of a general commercial
building. But, apart from any mere question of ostentation,
the business man or manufacturer frequently fails to seek
chemical advice, on questions of real importance, from igno-
rance of the manner of setting about it and sheer indolence in
ascertaining it. Many do not even seem to know that there is
such a man as a consulting chemist. May not some eyes be
opened and some extravagant waste of natural resources be
avoided, by persistent efforts of the manager of this central
home of chemistry, and the rule of thumb be replaced by
the rule of scales?

The American Chemical Society has gradually accumu-
lated a library of considerable magnitude, which has been
deposited of recent years with The Chemists' Club, which or-
ganization has acquired, by gift and purchase, many vol-
umes of its own. But the shelf -space has been so limited, that
but few of the books were accessible and even then could
only be consulted under unfavorable conditions. In the mag-
nificent " Chandler Hall" the entire library will be available
for consultation at all reasonable hours. It is also planned
to establish a collection of duplicates, to be loaned freely to
reputable chemists throughout the country. Here again, the
provision of a suitable working-place will serve not merely
the local interests, but, perhaps even more effectively, the
scattered outposts of chemical endeavor.

One of the chief disadvantages under which the American
investigator labors is the difficulty of obtaining research ma-
terial. The German or French experimenter can obtain,

126 MORRIS LOEB

within twenty-four hours, a specimen of virtually every chem-
ical substance that is in the market: the American depends
upon the stock of two or three importers, which must neces-
sarily be limited in regard to the rarer preparations, or he
must import directly, with inevitable delays in transit and
especially at the custom-house. The Chemical Museum is
planned to obviate this, by keeping as complete a collection of
substances as possible, in relatively small quantities, it is
true, which will be loaned to investigators who require mate-
rial for preliminary investigation. Such a preliminary test
may go far towards determining the course of a research and
deciding whether it is worth the chemist's while to procure
larger quantities. But, the projectors also hope to induce the
American chemists to deposit with the Museum samples of
all new substances prepared in their researches, to serve a
similar purpose as do type specimens in a museum of natural
history as standards of comparison for future investigators.
Here we should have the first chance of facilitating chemical
research in America by cooperation, instead of by subsi-
dizing individual investigations. It will take some time to
perfect the plans; but if it can be accomplished, the student
in a Rocky Mountain college will be within as easy reach of
his materials as his fellow in a large city of the East.

We have detailed some of the more striking advantages
which the new building is expected to confer upon the chemi-
cal profession as a whole, as well as upon its individual vo-
taries; is it an exaggeration to characterize the constitution
of the Chemists' Building Company itself as a new era in the
chemical industry of our country? In scanning the list of
shareholders, we find representatives of nearly every impor-
tant concern, or even the larger companies themselves; but
that this is not a "trust," in the sense so obnoxious to the
yellow journalist, is demonstrated by the conditions of the

THE CHEMISTS' BUILDING 127

partnership. No shareholder can receive more than 3 per
cent dividends, and the surplus cannot, under any circum-
stances, accrue to his benefit within the next fifty years.
This association, therefore, is not for individual profit, but
for the raising of the standards of chemical industry and re-
search in the United States. If we recognize what the Verein
zur Hebung der chemischen Industrie, founded by Hof mann
and Werner Siemens, has done for Germany, we may well
hope for further fruits of this initiative here. Perhaps this
building will house joint laboratories for the solution of
questions affecting all manufactures alike; or experimental
stations for the study of natural products not yet utilized;
or a cooperative bureau of standardization for analytical
methods; or a national welfare bureau for employees in chem-
ical factories. This building does not owe its erection to some
benevolent demigod, extending his protecting wing over
people unable to care for themselves; it is a building by the
chemists, of the chemists, and for the chemists. May it ever
serve as an exemplar of unselfish patriotic cooperation!

ADDRESS

AS PRESIDENT .OP, THE CHEMISTS' BUILDING COMPANY
ON THE OCCASION OF THE OPENING OF THE CHEM-
ISTS' BUILDING, MARCH 17, 1911 »

I RISE to welcome you on behalf of the directors and stock-
holders of the Chemists' Building Company, and to thank
you for the interest which your presence indicates in the
formal opening of a building which we believe to be the first
of its kind, not only in this country, but on earth. It is true
that Berlin possesses in the Hofmann-Haus a home for the
German Chemical Society and that London owes to the mu-
nificence of the late Ludwig Mond its Davy-Faraday Labo-
ratories for Chemical and Physical Research. But this new
building in which you find yourselves is planned to serve
under one roof the social, intellectual and practical needs
of the chemical profession not of New York alone, but of our
whole beloved country.

The means for its construction have been furnished by
men, many of whom can expect to share to but a slight degree
in the benefits of The Chemists' Club, which occupies so
much of its floor space. These shareholders see in it the in-
carnation of some of the ideals that led them to the pursuit
of chemistry, pure or applied, as their lifework.

For, strange as it may seem to the layman, who has seen
the ugliest blots on a landscape designated as chemical fac-
tories, who has sniffed with disgust a chemical odor, has been
urged to believe that the chemist's shadow contaminates
pure foods, and has been taught in school that alchemy
spelled fraud and sorcery, our science is one calculated to

1 Reprinted from Met. and Chem. Engineering, 9, 177 (1911).

OPENING OF CHEMISTS' BUILDING 129

develop the ideal side of human nature, and the chemist,
more perhaps than the votary of natural science or the de-
votee of the so-called humanities, is led to an intense interest
in human development.

Our science aspires not only to know, but also to do. On
the one hand, it leads us to delve into the secrets of nature,
in the minute atom as well as in the far distant stars, in the
living cell as well as in the crystallized relics of the convul-
sions from which this earth was born; on the other, it leads us
to apply this knowledge to the immediate needs of man, be
it in safeguarding his health, in ministering to his material
or esthetic wants, or in regulating his commerce and in facil-
itating his utilization of the earth's resources. These many
points of contact with nature and with human interest will be
the theme of the eminent men whom I shall have the privi-
lege of introducing this afternoon and will be illustrated at
greater length in the scientific meetings which are to follow;
it is enough that we recognize at this moment that this ver-
satility of method and of purpose must necessarily enlarge the
viewpoint of the chemist, and that we seek therein the mo-
tives for the ready cooperation in the present enterprise.

Our shareholders content themselves with a moderate re-
turn for their money and have agreed that any surplus profits
shall accrue to the benefit of chemical science. They hope
that the facilities afforded within these walls will redound
to the benefit of mankind and the prosperity of the country.

May I emphasize the word "facilities"? There are two
ways of aiding a man or a cause : by addition to the income or
reduction of the expense. The pecuniary result to the bene-
ficiary may be the same, but the moral one is far different; it
is not only the beggar who is pauperized by the cash gift and
uplifted by the aid which enables him to earn his own live-
lihood. Arts and sciences may be stimulated by prizes and

130 MORRIS LOEB

scholarships beyond a doubt, but the relation between donor
and recipient is not free from restraint, and the probability
of human error in the selection of the right incumbent makes
the method a wasteful one at best.

Far better is it to remove those obstacles which hamper all
work equally and are felt more severely by those whose means
are restricted and who have not yet earned the recognition
of the world at large. The laboratory*student is encumbered
by certain restrictions in America more than elsewhere. The
higher price of commodities affects him in many ways besides
the higher cost of living, rent of laboratory, installation of
equipment, purchase of supplies, salary of assistant, acquisition
of books. The advanced cost of labor militates against the
construction of certain grades of apparatus and the prepara-
tion of the rarer chemicals in this country; and a curiously
unscientific tariff law, while pretending to lift the duty from
articles required for educational purposes, practically forces
the colleges to make their purchases abroad and prevents
American dealers from carrying an adequate selection of im-
ported material. It is no exaggeration to state that this
duty-free importation clause, as interpreted by the United
States Treasury Department, forces the American chemist to
wait from two to three months before making an experiment
for which he could obtain his material in two or three days
if he were working abroad.

To remove these disadvantages in time and cost, to provide
easy access to books and apparatus, to make room for the
independent scientific worker, are the ideals which hovered
before the eyes of those who planned this present enterprise.
Time will show whether they can all be realized, but what-
ever is done in this beautiful building, which we are about to
dedicate, must open free opportunities to all and show favor-
itism toward none, if the trust imposed upon its management

OPENING OF CHEMISTS' BUILDING 131

be administered in the spirit of those who have contributed
toward its erection.

A library of the highest scientific importance and a mu-
seum of chemical substances will be available for every rep-
utable chemist; laboratories for temporary as well as for per-
manent use will be at the disposal of the earnest student;
help and advice will be extended to the struggling beginner;
good comradeship and hearty cooperation will characterize
The Chemists' Club, and this auditorium, soon to be named
after the first great chemist of American birth, will ever
minister to his ideal of the application of science to the use-
ful arts.

THE COAIr-TAR COLORS1

THE term "coal-tar colors" is applied to coloring matters
artificially prepared from coal-tar, chiefly from the hydro-
carbons extracted from it.

The first observation of a colored compound of this class
was made by Runge in 1834; but the real beginning of the
great modern color industry dates from 1856, when W. H.
Perkin obtained a violet dyestuff by oxidizing impure ani-
line with chromic acid, took out a patent for it, and com-
menced manufacturing it in England. Many other dyes were
subsequently obtained from aniline and the substances related
to it, by A. W. Hofmann, Griess, Girard, Lauth, and many
others. But the most sensational step was the preparation
by Graebe and Liebermann (1868) of a natural dyestuff —
viz., the coloring principle of madder-root — from the anthra-
cene of coal-tar. In 1880 indigo was first prepared, not from
coal-tar products, but by a purely synthetic method, and other
natural colors have since been prepared in a similar manner;
so that natural dyestuffs reproduced by artificial means
need not necessarily originate from coal-tar. The artificial
indigo and alizarin are not mere substitutes for the natural
indigo and madder; they are chemically identical with them,
and surpass them in purity, and their adaptability to special
methods in dyeing and printing often makes them even more
desirable. But as the cost of manufacture is high, they com-
pete with the natural products on about equal terms.

The color industry was first developed in England and
France, but the more thorough technical instruction at the

1 Reprinted from the New International Encyclopaedia (Dodd. Mead & Co., New
York, 1912, 6, 74-77), by permission of the Publishers.

THE COAL-TAR COLORS 133

German universities produced a body of skilled manufacturers
and investigators who soon took the lead. At present, in
addition to the great factories near Berlin, Frankfurt, Elber-
feld, and Mannheim, and a host of smaller ones in various
parts of Germany, German capital controls many of the
establishments in France, Russia, and other countries. The
United States possess few independent factories, and the list
of their products is rather limited; indeed, American dyers ap-
pear to call for a smaller range of dyestuffs than those of other
countries. A peculiar development of the last fifteen years is
the extension of the methods of the dye industry to the
production of artificial drugs, such as antipyrin, antifebrin,
etc., many of which are manufactured in the same establish-
ments which control the dye patents.

CLASSIFICATION. Artificial colors were formerly classified
merely according to the sources from which they were ob-
tained. Thus, many of them, including magenta, "aniline
blue," "aniline green," "aniline yellow," etc., were grouped
together as aniline colors. At present somewhat different
systems of classification are used by different authors, but all
systems are based exclusively on the chemical constitution
of the dyes.

Many attempts have been made to find a general answer
to the question : What must be the chemical nature of a car-
bon compound in order that it may be a dye? An all-embrac-
ing answer to this question has not yet been found. But ex-
perience has shown that the true dyestuffs exhibit peculiar
groupings of the constituent atoms. Such "chromophore"
groupings produce, however, only a tendency toward color,
but not necessarily colors; indeed, many compounds con-
taining them are perfectly colorless, and the majority of true
dyes become colorless if deprived of the small amount of
oxygen they contain, although their chromophore groups

134 MORRIS LOEB

may not be in the least affected. If, however, a chromo-
phore group is combined with certain other atomic groups,
the result is a dye. For example, the so-called azo-group
( — N=N — ) is chromophoric; the compound called azoben-
zene, CeH6 — N=N — C6H5, although colored red and evidently
containing the azo-group, is not a dye; but it becomes one
when the so-called amido-group (NH2) also is introduced into
its molecule, the compound C6H5 — N=N — C6H4NH2, called
amido-azobenzene, being a true dye. If, instead of the amido-
group, a hydroxyl group (OH) is introduced, the result is
again a dye (an orange one). Further, the tints of dyes are
produced by variation in the "substituting" groups which
replace hydrogen in the primitive molecule. Thus, the in-
troduction of the methyl group (CH3) generally increases
the violet tendency; the phenyl group (C6H5) produces bluish
tints; the naphthyl group (CioH7) a tendency toward brown-
red, etc. The relative position of the groups likewise plays
a large part in the determination of color. But, as we have
already observed, a definite and all-embracing rule does not
exist. Frequently compounds must enter into combination
with a base or an acid before they will fix themselves upon
the fibre, and then the tints are frequently affected by the
different bases or acids to a varying degree. For example,
alizarin dyes red with the hydroxide of aluminum, and black
with the hydroxide of iron.

For the purposes of the present sketch, the coal-tar colors
may be grouped in five classes: viz., the azo-colors; triphenyl-
carbinol derivatives; quinone derivatives; diphenyl-amine
derivatives; and indigo dyes.

Azo-CoLORS. The characteristic compound of this class
is azo-benzene, C6H5N=NCeH5, already mentioned above.
We have seen that the introduction of either NH2 or OH in
place of a hydrogen atom produces a coloring matter — yellow

THE COAL-TAR COLORS 135

in the former, orange in the latter instance. Replacing either
or both of the phenyl groups (C6H5) by more complex hydro-
carbon groups deepens the tone (with a tendency toward the
redder tints), increases the affinity for fibres, and dimin-
ishes the liability to fade. The earlier dyes of this class, such
as "aniline yellow," "Bismarck brown," chrysoidin, etc.,
were singularly brilliant, but were not fast; whereas the
browns and the many reds, ranging from scarlet to purple,
which are now produced under the names of ponceaux or
bordeaux, congos, quinoline red, etc., are exceedingly per-
manent. In manufacturing this class of dyes, nitrous acid is
allowed to act upon an ice-cold solution of the salt of any
primary base (like aniline), and the "diazo-salt" formed
is allowed to act on another base or a phenol; an endless
variety of combinations is thus possible.

TRIPHENYL-CARBINOL DERIVATIVES. These represent the
first discoveries in the aniline dyes, and some of them are
still produced on the largest possible scale. The fundamental
compound of the class is triphenyl-carbinol (CeH^sCOH,
and its derivatives are properly subdivided into rosanilines,
rosolic acids, and phthalems.

In the rosaniline group, two or three amido-groups (NH2)
are introduced in place of hydrogen atoms of the phenyls
(C6H5). The di-amido-compounds are green; the fri-amido-
compounds are red, violet, or blue. Strictly speaking, the
compounds thus obtained are not themselves dyes, but are
bases which must first be combined with suitable acids, and
thus brought into a soluble form. Their salts in the solid
condition are beautifully crystalline bodies, showing colors
quite different from those of the solutions, and having pecu-
liar lustres like those of beetles' wings. The solutions have
very intense colorations and stain animal fibres readily and
permanently, although they do not fix themselves easily

136 MORRIS LOEB

upon cotton or linen. They are the most brilliant and lively
dyes, but are strongly affected by sunlight, and are conse-
quently less useful than some dyes of other classes. They are
generally manufactured by oxidizing processes at a com-
paratively high temperature, whereby two or three simpler
compounds are welded, as it were, into compounds of com-
plex molecular structure. Thus, in the manufacture of the
well-known magenta dye (a tri-amido-compound) approxi-
mately equal quantities of aniline, ortho-toluidine, and para-
toluidine are heated from 8 to 10 hours with arsenic oxide to
190° C., in large iron kettles. A very thick mass results,
which can be extracted with hot water, and the compound
thus obtained is found to be made up of molecular quantities
of aniline, ortho-toluidine, and para-toluidine chemically
combined.

Rosolic acid and its derivatives are made by the condensa-
tion of various phenols, three phenols being condensed into
one compound of the rosolic acid group, just as the bases
are condensed into one compound of the rosaniline group.
The comparatively few dyes of this group give various shades
of red. The hydroxyl groups, and hence the acid character
of the phenols, remain unchanged in the products of conden-
sation; the latter therefore combine with bases, and then they
readily go into solution.

The phthaleins differ from the rosolic acids in so far as
one of the three phenyls of the triphenyl-carbinol is connected
in them with a carboxyl group (COOH), the other two
phenyls having one or more hydroxyls apiece, as in the rosolic
acids. The phthaleins were discovered by Adolph von Baeyer,
and are chiefly remarkable for the fluorescence of their alkali
salts in solution. They are prepared by heating phenols with
phthalic anhydride and a little sulphuric acid; when resorcin is
taken as the phenol, a very well-known compound is obtained,

THE COAL-TAR COLORS 137

which has been called fluorescein, while its sodium salt is
known as uranin. Solutions of the latter are yellow by trans-
mitted light, but bright green by reflected light. This fluo-
rescence is so intense that it is distinctly noticeable in ex-
tremely dilute solutions; so that this salt has been used to
trace subterranean watercourses supposed to connect two
neighboring bodies of water, the dye being thrown into one
of these and fluorescence being subsequently noticed in the
other. The potassium salt of a brominated fluorescei'n is
eosin, C2oH6O5Br4K2, with a magnificent red and yellow fluo-
rescence. These fluorescences disappear on the fibre, but
eosin and analogous substances impart very brilliant flesh-
tints to silk and wool.

THE QUINONE DERIVATIVES. These contain the charac-
teristic nucleus —

and are almost invariably colored, although they become
suitable for dyes only when they also contain several hy-
droxyl groups. By far the most important substance of this
class is alizarin, which was already mentioned as identical
with the active principle of madder. Anthracene, a coal-
tar hydrocarbon, is converted into anthraquinone by heat-
ing with potassium bichromate and sulphuric acid; the an-
thraquinone is acted upon by fuming sulphuric acid, and

138 MORRIS LOEB

the resulting compound is melted with caustic soda, yielding
a sodium salt of alizarin. This is soluble in water with a fine
red color, but does not fasten upon any kind of fibre. If, how-
ever, cotton is previously impregnated with salts of alumi-
num, iron, or chromium, the alizarin will form insoluble salts
("lakes") with these metals; and as the precipitation occurs
within the pores of the fibre, subsequent washing cannot re-
move it. Colors of this class of dyes are not suitable for
silk and wool, but are very intense and permanent when
properly applied to cotton.

THE DIPHENYLAMINE DERIVATIVES. These include many
varieties of dyes, such as the indulins, indophenols, thiazins,
etc. Their chemistry is too involved to be disposed of in a
few words. It may, however, be mentioned that their char-
acteristic groups are similar to anthraquinone, excepting that
the oxygen of the latter is replaced by sulphur, imido-groups,
etc. The more important dyes of this class include methy-
lene blue and aniline black.

INDIGO DYES. By far the most important of these is indigo
itself, a vegetable dye obtained from a tropical plant cul-
tivated in India since the earliest times. The sap of this
plant, when fermented under conditions excluding oxygen,
yields indigo white, a soluble material having the formula
Ci6Hi2N2O2; if the fermentation proceeds in the open air, in-
digo blue, Ci6HioN2O2, is produced. This substance is a deriv-
ative of the base called indol, C8H7N, which occurs ready-
formed, in small quantities, in many animal and vegetable
secretions. It can be prepared artificially from aniline and
chloraldehyde. When indigo was found to consist of two indol
molecules joined together and oxidized, the clue for the pro-
duction of artificial indigo was at hand. It has since been
found that any benzene derivative having a nitrogenous group
and a two-carbon group in the "ortho" position may give rise

THE COAL-TAR COLORS 139

to the formation of indigo. The first practical method, devised
by Baeyer in 1880, involved the action of potassium hydroxide
on ortho-nitropropiolic acid; but many other methods have
been devised since then, such as the action of melted potas-
sium hydroxide on bromacetanilid, the action of halogenated
acetone on aniline, etc. Indigo is one of the most reliable dye-
stuffs, both as to brilliancy and permanency, and there is
little difference in these respects between the natural and
artificial products. The finished compound can, however, only
be used after reduction to the soluble indigo-white, and
this makes its use in dyeing and printing somewhat cumber-
some. In some of the methods for preparing artificial indigo,
the fibre can be impregnated with one ingredient and the other
applied either in the dye- vat or from the printing-rolls; con-
sequently, indigo can be and is often directly prepared in
the quantities and in the places in which it is needed.

LIST OF COLORS. The following are some of the best
known commercial coal-tar colors, their molecular formulas,
and the principal methods employed in their manufacture.

Aldehyde Green. — See Aniline Green below.

Aniline Black, C3oH25N3, made by the oxidation of aniline with mineral
salts.

Aniline Blue (triphenyl-rosaniline hydrochloride), CssHssNaCl, made by
heating rosaniline, benzoic acid, and aniline, and subsequently adding
hydrochloric acid.

Aniline Brown, Bismarck Brown, or Phenylene Brown (triamidoazo-
benzene), C^HisNs, made by the action of nitrous acid on metaphenylene-
diamine.

Aniline Green, or Aldehyde Green, €221127^820, made by the action
of ordinary aldehyde on an acid solution of rosaniline sulphate and the sub-
sequent addition of sodium hyposulphite.

Aniline Orange. — This name is applied to various compounds made by
the action of amidosulphonic acids on phenols. The name is often applied
to the so-called Victoria Orange, CrHeN^Os.

Aniline Red. — See Fuchsin below.

Aniline Scarlet, Ci8HiSN2O4SNa, made by the action of diazoxylene on
naphthol-sulphonic acid.

Aniline Violet. — See Mauveih below.

140 MORRIS LOEB

Aniline Yellow (hydrochloride), CizHjzNsCl, made by the action of
nitrous acid on an excess of aniline.

Alizarin, Ci4H8O4, made artificially by successive treatments of anthra-
cene with chromic acid and fuming sulphuric acid, and melting the product
with potassium hydroxide. Among the dyes allied to alizarin are: Alizarin
Black, CioH6O4.NaHSO3; Alizarin Blue, Ci7H9NO4; Alizarin Orange,
C14H7NO6; and Alizarin Violet, or Gallein, C2oH10O7.

Auramin (hydrochloride), CnH^NsOCl, made by the successive action
of phosgene gas (carbon oxychloride) and ammonia upon dimethyl-aniline.

Aurantia (ammonium salt of hexanitro-diphenylamine), C^HsNyO^.
NH4, made by the action of nitric acid on methyl-diphenylamine.

Aurin, CigH^Os, made by the action of oxalic and sulphuric acids on
phenol.

Benzaldehyde Green. — See Malachite Green below.

Benzidine Red. — See Congo Red below.

Benzopurpurins, dyes of various red shades. They are chemically al-
lied to Congo Red (which see below), and are made by treating salts of
toluidine (which is made from nitrotoluene, and is analogous to benzidine)
with nitrous acid, and combining the resulting salts with a- and /2-naph-
thylamine-sulphonic acids.

Bismarck Brown. — See Aniline Brown above.

Blackley Blue. — See Indulin below.

Bordeaux. — See Ponceaux below.

Chryso'idin (hydrochloride), C^HisN^l, made by the action of diazo-
benzene chloride on metaphenylene-diamine in aqueous solution.

Congo Red, or Benzidine Red, C32H22N6S2O6Na2, made by the action
of nitrous acid and then of sodium naphthionate on benzidine hydro-
chloride.

Eosin, C2oH605Br4K2, or C2oHeO5Br4Na2, made by the action of bromine
on fluorescem.

Erythrosin, C20H6O5l4Na2, made by the action of iodine on fluorescem.

Fluoresce'in, C2oHi2O5, made by the action of phthalic acid anhydride
on resorcin.

Fwcfo^Rosaniline Hydrochloride, Magenta or Aniline Red, C2oH2oN3Cl,
made by the oxidation of toluidine and aniline in the presence of acids.

Gallem. — See Alizarin above.

Helianthin. — See Methyl Orange below.

Indigo. — See text of the article above.

Indulin, or Blackley Blue, CisHisNs, made by heating aniline salts with
amidoazobenzene.

Magenta. — See Fuchsin above.

Malachite Green, Benzaldehyde Green, or Victoria Green, 3C23H25N2C1.
2ZnCl2 + H20, made by the condensation of benzaldehyde with dimethyl-
aniline, and the subsequent addition of hydrochloric acid and zinc chloride.

Martius' Yellow, CioH5N2Q5SNa, made by the action of nitric acid on
a-naphthol-monosulphonic acid.

THE COAL-TAR COLORS 141

Mauvein (hydrochloride), or Aniline Violet, CarHgsNiCl, made by the
action of chromic acid on aniline containing some toluidine.

Methyl Orange, CwHiaNsSOsNa, made by the successive action of nitrous
acid and methylaniline upon para-amidobenzene-sulphonic acid; it is the
sodium salt of helianthin.

Methyl Violet, C24H28N3C1, made by oxidizing dimethyl-aniline with
metallic salts.

Methylene Blue, CieHisNsSCl, made by heating amido-dimethylaniline
with sulphide of iron.

Naphthol Yellow, CioH5N208SK, made by the action of nitric acid on
a-naphthol-trisulphonic acid.

Nigrosin, CigH^Ns, made by heating aniline salts with nitrobenzene.

Night Blue, C38H34N3O (the hydrochloride of this is the commercial dye),
made by heating pararosaniline with aniline and benzoic acid.

Pararosaniline (chloride), CigHigNsCl, made by oxidizing a mixture of
para-toluidine and aniline with arsenic acid, or nitrobenzene.

Phenylene Brown. — See Aniline Brown above.

Ponceaux, or Bordeaux. — Various derivatives of azonaphthalene.
"Ponceau 3R," Ci9Hi6N2O7S2Na2, is made by combining diazocymene
hydrochloride with /2-naphthol-disulphonic acid.

Primulin, CnHi^^ (?), made by the action of sulphuric acid on
thiotoluidine.

Resorcin Yellow, or Tropseolin O, C^HieNjjOsS, made by the action of
diazobenzene-sulphonic acid on resorcin.

Rhodamine (hydrochloride), C28H3iN203Cl, made by the action of
phosphorous trichloride on fluorescein, and treatment of the product with
diethylamine.

Roccellin, C20Hi3N2O4SNa, made by the action of /?-naphthol on the
diazo-compound of naphthionic acid.

Rosaniline. — See Fuchsin above.

Rose Bengale, C2oH4Cl2l2O5K2, made by the successive action of chlor-
ine and iodine upon fluorescei'n.

Rosolic Acid, C20Hi6O3, closely allied to aurin; neither aurin nor rosolic
acid is specially valuable.

Safranin, C2iH2iN4Cl, made by the oxidation of a mixture of tolulene-
diamine and aniline or toluidine.

Tropoeolin. — This name is applied to various compounds made by the
successive action of nitrous acid and phenols upon amidobenzene sul-
phonic acids. See Resorcin Yellow above.

Uranin, C2oGi0O5Na2, the sodium salt of fluorescein (which also see
above).

Victoria Green. — See Malachite Green above.

Victoria Orange. — See Aniline Orange above.

BIBLIOGRAPHY. Schultz, Die Chemie des Steinkohlenteers (Brunswick,
1890); Villon, Traite pratique des matieres color antes artificielles (Paris,
1890) ; Cazeneuve, Repertoire analytique des matieres colorantes artificielles

142 MORRIS LOEB

(Lyons, 1893) ; Schultz and Julius, Systematic Survey of the Organic Coloring
Matters, translated by Green (New York, 1894) ; Hurst, Dictionary of the
Coal-Tar Colors (London, 1896); Lefevre, Traiti des matieres color antes
organiques artificelles (2 vols., Paris, 1896) ; Seyewetz and Sisley, Chimie des
matieres colorantes artificielks (Paris, 1897); Benedikt, Chemistry of the
Coal-Tar Colors, translated by Knecht (London, 1900) ; Nietzki, Chemistry
of the Organic Dyestiiffs, translated by Collin and Richardson (London,
1892; newer German edition, Berlin, 1901). An annual devoted to the
progress of the coal-tar industry has, since 1877, been published in Berlin
by Friedlander, under the title, Fortschritte der Theerfarben-Industrie und
verwandter Industriezweige.

THE PERIODIC LAW1

THE name "Periodic Law" is given to the generally ac-
cepted embodiment of the relations existing between the
various properties of the chemical elements, so far as they
can be compared with one another. It may be stated as fol-
lows : // the elements are arranged in the order of their atomic
weights, each of their properties varies as a periodic function
of the atomic weight.

Ever since the work of Richter, Proust, and Dalton had
established the idea of fixed numerical values attaching to
the ingredients of compounds (an idea which was deduced by
Dalton from the hypothetical existence of individual atoms,
identical in size, mass and other properties for any one ele-
ment), chemists sought to deduce a closer relationship be-
tween the various elements from a comparison of the masses
of their respective atoms. The first attempt was that made by
Dr. Prout in 1815 to prove that all the atomic weights were
even multiples of the atomic weight of hydrogen, and that
the latter was the only primitive element, from which the
others were derived by processes of condensation. It was
soon found that very few elements possessed atomic weights
that could be expressed by integers, when the atomic weight
of hydrogen was set at unity, and Prout's law was gradu-
ally modified to state that one half the atomic weight of hy-
drogen, then that one-quarter, should be taken as the real
standard. Refinements of investigation have since es-
tablished the relative atomic weights to the second place
of decimals, and it can now be asserted that the number

1 Reprinted from the New International Encyclopaedia (Dodd, Mead & Co., New
York, 1912, 15, 593-597), by permission of the Publishers.

144 MORRIS LOEB

of exact coincidences with Prout's law, as compared with
that of deviations from it, is not much greater than what
would be expected by the theory of chances. Prout's law,
has, therefore, been practically abandoned. On the other
hand, interesting relations were found to exist between
the atomic weights of similar elements. Thus Doebereiner
established, in 1829, his so-called triads, sets of three closely
related elements whose atomic weights were approximately
in arithmetical progression, as lithium (7), sodium (23), and
potassium (39); calcium (40), strontium (88), and barium
(136) ; sulphur (32), selenium (79), and tellurium (127) ; chlo-
rine (35.5), bromine (80), and iodine (127); iron (56), nickel
(57), and cobalt (58). These triads were later extended to
include longer sets, and it was also pointed out that the con-
stant differences were in many cases multiples of 16, the atomic
weight of oxygen, whence it was assumed that the heav-
ier elements of a group might be oxides of the lightest, thus
reducing the number of primordial elements considerably.
The idea of connecting all the atomic weights in a single
progression wherein similar elements recurred at regular
intervals seems to have first struck de Chaucourtois, and
shortly afterwards Newlands; but the law in its complete
form is due to Mendeleeff and Lothar Meyer, who reached
the same conclusion independently in 1869. As Mendeleeff's
exposition was by far the more convincing, he has been given
the greatest share of the credit.

A good idea of the fundamental principle can be obtained
from the accompanying figure, in which the maximum va-
lencies in the elements and their melting-points are shown
to be periodically related to the atomic weights. The latter
are laid off as abscissas, and the valencies and melting-points
as ordinates, on perfectly arbitrary scales. It will be seen
that the two curves connecting the respective points are un-

THE PERIODIC LAW

145

dulatory, with well-defined maxima and minima, which occur
at regular intervals. The curves for most of the other prop-
erties which are capable of precise measurement are found to
have a similar character; the maxima and minima, of course,
do not always coincide with the same elements in one curve
as in another, but the elements which occupy similar positions
on one curve are also found to be similarly located on another.
It is especially noticeable, moreover, that such curves indi-
cate a relationship between the groups of elements, as well as
between the individual elements of each single group. Thus
the properties of the alkaline-earth metals are always found
to be intermediate between those of the alkalies and those
of the aluminum group. Breaks in the continuity of the
curves indicate lack of sufficient experimental data. -t ....

Centigrade

70 80 90 100 110 120 130 140 150 160 170 "180 190 200 21Q-
ATOMIC WBIAHTS

The arrangement of the elements, as shown in the accom-
panying table (p. 148), is the one generally adopted at pre-
sent, and includes all the well-known elements. An asterisk
marks the elements discovered since 1869. Hydrogen occupies
a unique position, and is generally omitted from the classifi-
cation. Argon, helium, neon, and krypton cannot be properly
included as yet, because their chemical behavior is still un-
known. The vertical columns include the elements most
closely associated with one another, and are known as Groups
I, II, etc. ; horizontally, we have the Series 1,2,3, etc., in which
the similarities are not great, excepting that a parallelism
exists between the elements of one series as compared
with those of another. The elements in odd-numbered series
bear a closer resemblance to one another than they do to the

146 MORRIS LOEB

elements of the intervening even-numbered series, and vice
versa, so that it has been found expedient to make two divi-
sions of each group, as will be seen in the table, — the odd-
numbered series being set upon one side, the even-numbered
upon the other. In the eighth group occur triplets of closely
analogous elements to be discussed below. Arrangements into
fifteen or more individual groups, in place of the twin and
triple groups here shown, have been suggested, but not gen-
erally adopted. Mention should also be made of the fact that
this table can be constructed by writing the elements in the
order of their atomic weights along a screw-line of slight pitch
upon the surface of a cylinder, and then, as it were, unrolling
the cylinder. Various efforts have been made to connect all
the atomic weights by a graphic equation, which would pro-
vide for an arrangement on some other kind of a spiral curve,
either on a plane or in space, but they have been only moder-
ately successful.

Before proceeding with a discussion of the details of the
table, it may be well to inquire what significance can be at-
tached to this periodic variability of properties as functions
of the atomic weight. The many attempts to connect the
atomic masses themselves in arithmetical relations would
indicate a widespread opinion that the substances now called
elements are really compounds of simpler substances, whose
particles have a finite mass and represent individuals of dis-
tinct chemical properties, so that the chemical elements in
each of the periodic groups might be likened to one of the
"homologous series" of organic compounds. This view really
antedates the periodic law, but fails in large measure to ac-
count for the resemblance existing between adjacent members
of different groups. Many, especially Sir William Crookes,
have held that the atoms are really fortuitous agglomerates
of an indifferent primordial element, and that atoms of ap-

THE PERIODIC LAW 147

proximately the same mass behave similarly because they vi-
brate similarly, while atoms of greater mass might vibrate
harmoniously with the smaller ones. It is difficult to explain,
according to this hypothesis of the "genesis of the elements,"
why their number should be as limited as it is. But some
facts are known, vaguely pointing to the idea that the atoms
of elements within the same periodic group are capable of
vibrating at harmonically related rates, and that the great
majority of chemical and physical properties depend upon
atomic vibrations. It may, however, be argued that just as
violin-strings may be composed of different materials and
yet vibrate together according to common laws, so may the
elements be composed of as many individual materials and
still exhibit a periodic recurrence of properties, if the latter
depend upon the harmonic vibrations of the atoms. Until
much additional proof has been brought, the periodic law,
while furnishing a vague indication, cannot be taken as posi-
tive evidence of the qualitative unity of matter.

In the table it will be found that the first group contains the
univalent elements, the second group those which are divalent,
and so on up to the seventh, where the maximum valency is
seven. The maximum valency of the elements of the eighth
group may be set at eight, but their compounds rarely ex-
hibit so high a valency, and in many other respects this eighth
group is rather anomalous and is taken as a transition group
between the seventh and the first. Thus the three elements,
copper, silver, and gold belong, with respect to many of their
properties, especially when uncombined, in the eighth group;
but their valency is usually low, and many of their salts are
so similar to those of sodium that it is often found expedient
to place them in the first group, in the positions occupied in
the table by their names inclosed in parentheses. The va-
lencies refer especially to the stable oxides. Stable compounds

3 •

"

nga
65.

Vanadium
51.4

Columbi
93.7

Uranium
239.6

ndium'
44.1

!«*

38

o

Yttrium*
8.9

Erbium
166.3

Lithi
7.

Rubidi
85.4

Is

<»H3s ~

THE PERIODIC LAW 149

of hydrogen occur only in the fourth, fifth, sixth, and seventh
groups, four atoms of hydrogen combining with one of each
element of the fourth group, and this amount decreasing
until we find the halogens in the seventh group univalent
toward hydrogen. The first group includes the most electro-
positive elements, and there is a steady transition toward
the electro-negative end of the series in the seventh group,
while the eighth group shows a rather sudden return toward
the electro-positive side. The majority of the compounds
derived from elements at the left end of the table are soluble,
colorless, and volatile, whereas these properties change from
left to right until we find the maximum of insolubility, color,
and resistance to heat in the lower right hand of the table.
It is also possible to select analogous compounds of the differ-
ent elements and find those of similar properties falling within
a well-marked zone upon the chart. Mendeleeff, in his origi-
nal essay, added the following: (1) The elements which have
the lowest atomic weights are those most widely distributed
in nature, and also represent the most typical characteristics
found in the second series of the table; (2) the atomic weight
determines the character of an element; (3) from a considera-
tion of their position in the system new analogies can be dis-
covered between elements; (4) it may be expected that new
elements should be discovered to fill blank spaces within
the table, and their properties can be predicted from a con-
sideration of those of the adjacent elements; (5) errors in the
assumed atomic weights may be detected through an irregu-
larity in the position of the element in the periodic system.
All of these statements have been verified, and the im-
mediate acceptance of Mendeleeff' s views was facilitated
especially by the sensational discovery of a number of ele-
ments whose properties agreed accurately with those pre-
dicted by Mendeleeff. Thus gallium, germanium, and scan-
dium had been completely described with respect to their

150 MORRIS LOEB

own properties and those of their compounds before they
were actually discovered. Success has also attended the at-
tempts to correct atomic weights in several cases where the
elements appeared misplaced in the original tables and
were assigned to positions more in accordance with their
properties, but necessitating the assignment of new atomic
weights. The weakest point of the table lies in the position
of tellurium, which should fall into the sixth group, but is
found to have a higher atomic weight than iodine, which un-
doubtedly belongs to the same series in the seventh group.
Efforts to explain this discrepancy have so far been unavail-
ing. There are also a number of elements derived from the so-
called rare earths whose place in the system is not readily as-
signable. In the latter case, however, it may be said, as well
as in that of the atmospheric gases, argon, helium, neon, and
krypton, that their properties and atomic weights are not so
well established as to cast doubt upon the theory through
their failure to coincide with it. One interesting result of the
theory is that of limiting the probable number of chemical
elements to about 120, since the actual number of blank
spaces is limited, and since it is extremely unlikely that any
elements remain to be discovered with an atomic weight less
than that of hydrogen or greater than that of uranium.

Among the physical properties which appear as periodic
functions of the atomic weight may be mentioned the densi-
ties of the uncombined elements and of their oxides, fusi-
bility, atomic volume, crystalline structure of the compounds,
coefficient of expansion, refractive index, conductivity for
heat and electricity, color, and velocity as ions.

As an indication of some purely chemical periodicities the
following conspectus has been arranged, in which the elements
are indicated by their positions in the above table, and are
generally enumerated in such order that the one which shows
the property in the most marked degree has precedence. The

THE PERIODIC LAW 151

maximum valency of the elements toward oxygen is indicated
throughout by the Roman numeral of each group, omitting
the "peroxides," in which the oxygen appears to be linked in
a different manner.

Maximum valency toward hydrogen in stable volatile compounds: —

Univalent: VII; 2, 3, 5, 7; powerfully acid hydrogen compounds.

Divalent: VI; 2, 3, 5, 7; faintly acid hydrogen compounds.

Trivalent: V; 2, 3, 5, 7; basic acid hydrogen compounds.

Quadrivalent: IV; 2, 3, 5; neutral acid hydrogen compounds.
Maximum number of hydroxyls in basic compounds : —

One: I; 1, 2, 3, 6, 8. Ill; 11. VIH; 6 (c and d).

Two: II; 2, 4, 6, 8, 3, 5, 7, 11. IV; 11. VIII; 4 (bed).

Three: III; 3, 4, 5, 6, 7, 8, 10, 12. V; 11. VII; 4. VIII; 4a.
Minimum valency in oxygen acids: —

One: VII; 3, 5, 7.

Three: V; 2, 3, 5, 7. VI; 3, 5, 7.

Four: IV; 2, 4, 3, 5, 7, 11.

Five: V; 4, 6, 10.

Six: VI; 4, 6, 10. VH; 4. VIII; 4a.
Tendency to liberate hydrogen from water below red heat: —

I; 2, 3, 4, 6, 8. II; 2, 3, 4, 6, 8. VIH; 4a.
Tendency to liberate oxygen from water: —

VII; 2, 3, 5.
Elements whose chlorides are unstable toward water: —

V; 3, 5, 7, 11, 4, 6, 10, 12. VI; 10, 6, 4.

Elements whose sulphides can be precipitated from dilute acid solu-
tion : —

VHI; 4d, 6 (abed), 10 (abed). II; 11, 7. HI; 11, 7. IV; 11, 7, 5.

V; 11, 7, 5. VI; 12, 10, 6.
Ability to form alums with the sulphates of I; 2, 4, 6, 8: —

III; 2, 4, 6, 10. VI; 4. VII; 4. VIII; 4a.
Ability to form volatile compounds with organic radicles : —

With one methyl group: I; 3. VII; 2, 3, 5, 7.

With two methyl groups: H; 3, 5, 7, 11. VI; 2, 3, 5, 7.

With three methyl groups: HI; 2, 3, 5, 7, 11. V; 2, 3, 5, 7, 11.

With four methyl groups: IV; 2, 3, 5, 7, 11.
Ability to form complex bases with ammonia: —

VIII; 4 (cd), 6 (abed), 10 (abed). VI; 4. II; 3, 11.
Consult: Newlands, On the Discovery of the Periodic Law and on Rela-
tions Among the Atomic Weights (London, 1884) ; Huth, Das periodische
Gesetz der Atomgewichte und das naturliche System der Elemente (Frankfurt
a. O., 1884) ; Belar, Das periodische Gesetz und das naturliche System der
Elemente (Laibach, 1897); Mendeleeff, "The Principles of Chemistry," in
A Library of Universal Literature (New York, 1901); Venable, The Develop-
ment of the Periodic Law (Easton, Pa., 1896).

THE EIGHTH INTERNATIONAL CONGRESS
OF APPLIED CHEMISTRY1

WITHIN a few weeks will occur an event of supreme im-
portance to American chemists and especially to those inter-
ested in the branches of our science to which this Journal is
especially devoted : — the meeting, in Washington and New
York, of the International Congress of Applied Chemistry.
Strictly speaking, this is not the first time that such an
organization has met on American soil, since the first im-
petus to the plan of these international meetings seems to
have been derived from the sessions of foreign and American
chemists who attended the Columbian Exhibition in Chicago
in 1893. Every World's Fair has, in recent years, been ac-
companied by meetings of specialists in sciences and arts; but
it must be remembered that they bear the relation of what
is popularly called a side-show to the Exhibition itself. They
are more or less haphazard in their relation to the general
world of science, and there is no continuity of management
from one occasion to the next. The various international
scientific congresses are autonomous; the experiences gathered
at one meeting are utilized in the preparation for the next
one; special problems are committed to the care of qualified
experts, for the report of authoritative opinion to the next
gathering, and the way is paved for that general world-wide
cooperation in the advancement of knowledge and the per-
fection of its utilization, which has been within narrower
limits the chief virtue of the various national organizations.

It is just two hundred and fifty years since the Royal

1 Editorial, reprinted from Journ. Ind. and Eng. Chem., p. 556, 1912.

CONGRESS OF APPLIED CHEMISTRY 153

Society was incorporated in London, — with the sole excep-
tion of the Accademia dei Lincei, probably the oldest existing
society for the exchange of knowledge between the devotees
of exact and natural sciences. For nearly two centuries these
societies were not only close corporations but also practically
local clubs. The greater diffusion of scientific learning, as
well as the increased means of communication by railroad
and telephone, led to the establishment of national associa-
tions for the advancement of science (with more liberal terms
of membership) having the added feature that meetings were
never held twice in succession in the same city. A natural
outgrowth was the national society for the promotion of
some particular science. Since increased specialization soon
made it impossible for anybody to follow understandingly
the sessions of general associations, these met in sections —
a circumstance which led to the development of a yet closer
form of union among their respective members.

Thus, in chemistry at least, each great nation now possesses
one or more special societies, not restricted as to localities
or qualifications, as is the case with the academy or institute,
but open to every person interested in the science. At the
last annual meeting of the American Chemical Society there
were assembled as many members as would have been deemed
a fair attendance for the entire American Association for the
Advancement of Science, not very many years ago. It is un-
necessary to descant here on the advantages of oral discus-
sion, supplemented by the pleasures of social intercourse,
which make these general sessions so attractive, any more
than it is important to point out the same gregarious instinct,
which has led to the successful institution of so many local
sections, with their well-attended stated meetings. But we
must emphasize the fact that local chemical societies led a
very precarious existence until the more powerful national

154 MORRIS LOEB

organization enabled them to gather strength by coopera-
tion and let them experience the stimulus of generous rivalry.

And now we have entered into a new era, practically with
the opening of the twentieth century, that of the utter aboli-
tion of national boundaries so far as scientific endeavor is
concerned. A new chemical discovery in Paris is known in
London, New York and Tokio in far less time than was con-
sumed in the transmission of Priestley's or Cavendish's com-
munications to the Royal Society in London, and the time
is rapidly passing when the possession and guarding of a
scientific secret could be deemed a national advantage. If it
be deemed conducive to international amity that the young
men of all nations should meet at the Olympian games, in
contests of brawn and motor-nerves, how much more impor-
tant is it that there be occasional interchanges of thought
and knowledge! And yet, we wonder whether the press of
New York will afford as many paragraphs to the forthcoming
International Congress of Applied Chemistry, for matter
supplied to it free of expense, as it has published pages of
expensive cablegrams from Stockholm? We do not expect
any mobs of frenzied cheerers to throng around the arena
of scientific debate; and yet we know that the impression
which our foreign visitors will take home of the progress in
American science and scientific industry will be of far greater
importance to the esteem in which our country will be held
abroad, than the number of cups which the " Finland " will
bring home from Stockholm. Our individual responsibility
in this Congress is as great as our individual opportunity.

To meet the leaders of chemical knowledge and of chemical
manufacture, from abroad as well as at home, to listen to a free
exchange of thought and practical experience, are privileges
for which innumerable chemists have traveled to Berlin, Lon-
don, Paris, Vienna, and Rome. We all now have these chances

CONGRESS OF APPLIED CHEMISTRY 155

at home, coupled with the opportunity to benefit by free and
generous criticism of whatever we may desire to bring to
their view. In chemical industry, at least, mediaeval secre-
tiveness is breaking down in favor of frank exchange of experi-
ences.

That the scientific importance of the approaching Con-
gress is thoroughly realized may be gathered from the fact
that upwards of six hundred papers have already been ac-
cepted and are being printed, ready for distribution at the
Congress itself. In view of the stringent rules of acceptance
which have been adopted, and the early date set for the sub-
mission of the papers themselves, it would probably have
been easier for the authors to secure publication in the jour-
nals of then1 respective national chemical societies, had they
not recognized the paramount claims of this international
scientific gathering.

The American committee of arrangements is bending every
effort to ward making the sessions agreeable to the participants;
they are particularly anxious to make this Congress memor-
able for the promptness with which it shall transact its busi-
ness, the smoothness with which the machinery of entertain-
ing its members shall revolve and the completeness with which
their comfort may be considered. This means as full coopera-
tion on the part of every American chemist as has been cheer-
fully afforded by the hard-working members of the various
committees. It may be taken for granted that every chemist
who can get away from his work, no matter in what part of
the United States he resides, will be anxious to attend the
Congress, not only for the selfish reasons already stated, but
also for the patriotic one of adding by his own presence to the
prestige of the greatest chemical function which is likely to
occur here for many a year. . . .

CHEMISTRY AND CIVILIZATION1

THAT invention is one of the chief factors in the world's
progress, and that scientific investigation is at least coordi-
nate with geographical discovery in widening the bounds set
to human comfort and well-being, are assertions which may
well be called axiomatic. To discuss the influence of scientific
discovery upon civilization might seem a sort of supereroga-
tion, a mere rhapsody on man's wit and energy; even the
slightest hint that all invention has not made for progress,
industrial or cultural, may possibly be taken as the mark of
black pessimism or whimsical conservatism. Yet no other
chain of events has proven, on nearer view, to have main-
tained a single direction; and that historian is not deemed un-
patriotic who recites impartially the failures as well as the
successes in his country's record, especially if a study of the
darker phases may lead to an avoidance of future pitfalls.
Thus, too, not every scientific theory or practical invention
must necessarily have been in the line of real progress; some
may have led to the squandering of nature's bounty, or per-
haps to the temporary disregard of some more important
line of research. It may, therefore, be both fruitful and in-
structive to attempt a closer study of the ultimate, as well
as the immediate effects of such innovations; besides obtain-
ing a more stereoscopic picture of an important branch of
human activity, we may derive some useful lesson, at a time
when the gradual exhaustion of the earth's stored wealth is
giving food for anxious thought. In attempting to measure

1 The unfinished introduction to a projected treatise ; found in manuscript,
1912.

CHEMISTRY AND CIVILIZATION 157

the effect of a scientific invention upon civilization, we must
proceed rather differently than would the historian of philo-
sophic or religious, economic or political, development. In
exact science, at least, no hypothesis can be so erroneous as
to work practical harm, except possibly by retarding the adop-
tion of a correcter view; and who would try to estimate the
amount of such retardation? Based upon the observation
of solid facts, a hypothesis is accepted so far as it seems to
connect them with one another, but receives scant attention
so long as it does not lead to equally positive results. A false
ethical, economic or political theory may enjoy universal
credence for generations, before its evil effects upon the
commonwealth shall have been recognized and corrected
by what is usually termed reformation or revolution. Scien-
tific thought has a scarcely perceptible influence upon a peo-
ple; it is the practice by which they are helped or harmed.
For this reason, the scientific discoverer must be content to
see his work popularized by the inventor, and the Wollastons,
Henrys and Hertzes are unknown to those for whom Daguerre,
Edison and Marconi are household words.

The influence of a scientific invention, put to practical use,
may be felt in various directions: it may assist the culture of
the individual, by opening up new channels of thought or
providing new means of aesthetic enjoyment; it may increase
our physical comfort, by placing in our hands new weapons
wherewith to combat hunger, disease, heat, cold, and other
elemental forces; it may modify the intercourse of individuals
and peoples, by devising new modes of communication and
transportation; it may dislocate political relation, by creating
more potent engines of offense or defense; it may, tempo-
rarily at least, profoundly alter the commercial prosperity of
whole provinces, creating new sources of wealth in one local-
ity, and depreciating the product of another; finally, it may

158 MORRIS LOEB

have a share in determining the entire problem of the possi-
bility of human existence upon this earth, on the one hand by
promoting a more efficient utilization of natural resources,
on the other, by inducing us to squander futilely, within a
lifetime, material that has been accumulated during untold
ages. Rarely will close analysis permit the conclusion that
an invention has wielded only one kind of influence; seldom
will no interest be found to have suffered from something that
has produced profit and enjoyment for the multitude; practi-
cally never, I firmly believe, has the evil preponderated so
largely over the good, that a corrective could not be applied
in time to prevent an irremediable harm. And yet, the pop-
ular mind is far from applying true standards to the estimate
of certain inventions, that have been hailed as the achieve-
ments of our era.

Let me recite a few examples, in illustration of my last
assertion, without treating them as fully as if they came en-
tirely within the scope of my inquiry.

Is it not generally conceded that the tremendous gain in
individual efficiency, derived from the introduction of tele-
graph and telephone, is offset to a greater or lesser extent by
an increased nervous irritability and decreased vitality? Has
not the diffusion of knowledge, through the introduction of
the power press, with the consequent cheapening of printed
matter, been accompanied by the virtual submergence of
good literature under a flood of ephemeral reading-matter;
just as the typewriter, with all its advantages, is surely un-
dermining the elegance of our diction? All these and kindred
inventions have vastly facilitated talking 'to our fellow-men;
have they improved the quality of our conversation or
strengthened our thinking-processes? We can deny this
without wishing [for one moment that these potent aids to
communication had not been invented.] . . .

CHEMISTRY AND CIVILIZATION 159

Dismissing, as incidental to a mere plaything, the reckless
disregard of public safety, as well as the bad manners of the
"speeder," ought we not to realize that the undoubted en-
joyment and practical convenience of automobiling requires
for the locomotion of the single individual an utterly dispro-
portionate amount of energy, whether we measure it in the
conventional horse power, or in the stored-up solar energy
represented by the petroleum burnt up for the propulsion,
and the ores, coal, and gums utilized for the construction of
this modern conveyance?

Perhaps the motion-picture, as an instrument for enter-
tainment and instruction, is too novel to justify an estimate
of its good and evil effects; some hail it as a potent aid to edu-
cation, while others invoke the police to curb its power to
promote immorality and vice. It is thought a dangerous com-
petitor to the theatre; though we may well doubt whether
its rivalry will be felt by the higher drama so much as by the
vaudeville and melodrama, whose decay can hardly be de-
plored. But the economic influence of these cheap and all-
pervasive picture-shows has yet to be estimated, both in the
amount of money extracted from that portion of the popu-
lation which can least afford it, and in the hours diverted
from more healthful recreation, as well as from gainful occu-
pation.

Coming to a far more serious problem of world-wide im-
port, we have the installation of those modern means of trans-
portation which have so vastly extended the distance from
which we can derive food and commodities. It would, of
course, require years of study by a trained economist to evalu-
ate all the effects upon commerce, as well as upon the sub-
sistence of urban and rural population, which have resulted
from the gradual removal of the grain-farmer and stock-raiser
from the neighborhood of the consumer. The sociologist, on

160 MORRIS LOEB

the other hand, must recognize the difficulty of the task of
tracing the influence of these causes in encouraging the con-
centration into large centers, in depleting the older rural com-
munities of their more energetic elements, and in eliminating,
more or less completely, that element of the village com-
munity which formed the connecting link between city and
country life of the past; while he hails the gradual extension
of the benefits of civilization over the entire earth. Popular
opinion, pointing to the reduced price of food-stuffs, clothing
and other comforts, to the freedom of migration for the in-
dividual, the wage-earning opportunities for the myriads
employed in the carrying trades, will unhesitatingly answer
in the affirmative any question as to the value of these
modes of communication. Public opinion on this topic will
doubtless be justified at that time, when the increased popu-
lation of the earth will demand the exploitation of all its
resources, the tilling of every arable field, the harnessing of
every horse-power.

At the present juncture, however, the physicist cannot
join the chorus of praise, until he has satisfied himself on cer-
tain points that come more closely within his ken. For him,
money as a standard of comparison must 'ever be secondary
to the amount of energy, — in the dynamic sense, — requi-
site for the attainment of a desired object. So far as this en-
ergy has a market value, as in the wages for day-labor or in
the price of fuel, coin may form a temporary expedient for
casting a balance, — less reliable, I fear, than most schools of
political economy will admit.

I have been struck, comparing the prices of certain staple
commodities, as a bushel of wheat, a cow, a work-horse, with
a laborer's wage in ancient Jerusalem, imperial Rome and
modern New York, by the apparent constancy of the ratios,
which might well lead us to look to departures from such a

CHEMISTRY AND CIVILIZATION 161

fixed mean, — whether we estimate them in gold or in day's
work, — as the tone measures of the fluctuation in mundane
prosperity. But if we go to over-populated China and barely-
settled Alaska, we note such astounding dislocations of these
proportions, that we realize to what extent their apparent
constancy is predicated upon the equilibrium between natu-
ral resources and man's demand thereon; or rather, upon such
a superabundance of these resources, that human consump-
tion does not noticeably affect them. During the twenty-five
or thirty centuries of historic times preceding the nineteenth
this condition was maintained. Our forefathers drew their
sustenance from the surface of the earth and consumed rather
less than was derived from the solar energy during their re-
spective lives. In the nineteenth century commenced that
wholesale exploitation, which has drawn in ever-increasing
quantity upon the stored-up riches of the earth's interior. So
that within the last thirty years we have been forced to
recognize that the future progress, if not existence, of the
human race is threatened by the gradual exhaustion of our
supplies of food and fuel. Even that most unreasoning opti-
mist, the American politician, prates of the importance of
conserving our natural resources.

The great break in the continuity of dynasties and nations
which the historian entitles the French Revolution coincides
more or less closely with that still more portentous change
in human history, the substitution of mechanical methods of
manufacture for handicraft. Simultaneously began the de-
velopment of chemical factories to which the historian has
paid no attention, though its effect reached further than even
the political economist ordinarily can recognize. There
were countless revolutions before the one which dethroned
Louis XVI, and man had learned to harness animals, wind
and water to replace his own meagre forces, and had shaped

162 MORRIS LOEB

tools and built machines, many centuries before the birth of
Watt and Arkwright. Just so, many operations that involve
a change of substance, and are therefore properly classed
among chemical processes, had their origin in prehistoric
times. Ore-smelting, tanning, dyeing, the making of cement,
pottery and glass are good examples of industries now pe-
culiarly within the chemist's control, but which were prac-
ticed by rule of thumb, by skilled artisans, ever since the
dawn of civilization.

Then, again, the preparation of perfumes and cosmetics,
medicines and poisons, had been perfected long before the
Roman era, and these arts were preserved by Jews and Arabs
during the barbarous relapse of mediaeval Europe; so that
there was a constant development, from the magic of the
Egyptian priesthood, through the alchemy of a Geber and an
Albertus Magnus, the spagirism of a Paracelsus and a Glauber,
to the chemistry of a Becher and a Boyle. By the middle of
the eighteenth century, scientific chemistry had reached a
point where it could give a rational explanation of some of
the industrial processes of the period, and could seek to con-
trol their operations by distinct tests and to improve them
upon the basis of laboratory experiments. But the essential
step toward the domination of scientific theory over empir-
ical manufacture was taken when Bergman, Lavoisier and
their contemporaries recognized the constant quantitative
composition of chemical substance; for now it became certain
that the proportion of ingredients which proved most ad-
vantageous in a laboratory experiment must be the ratio to
which the manufacturer should adhere; the percentage of
useful substances contained in raw materials from various
sources could be estimated. At times it would be discovered
that certain admixtures, prescribed for centuries by tradi-
tional formularies, contributed nothing to the desired com-

CHEMISTRY AND CIVILIZATION 163

pound, and could be omitted with the same impunity as could
the magic incantations of the alchemists.

Lavoisier perished in the French Revolution; but this
same political upheaval gave an indirect impetus to chemical
manufacture in the modern sense. For the ensuing wars, with
their commercial reprisals which cut off both France and
England from their existing sources of supply, stimulated
attempts to substitute artificial for natural commodities, and
the governments offered premiums for the invention of pro-
cesses which would manufacture articles at home that were
heretofore imported from the colonies or abroad. Hence arose
the beet-sugar industry, and the Leblanc process for making
artificial soda, to replace the ashes of wood and seaweed no
longer available in sufficient quantities for the making of glass,
soap, etc. The Leblanc process, however, called for a plenti-
ful supply of cheap sulphuric acid and liberated large quan-
tities of hydrochloric acid, for which an outlet was found in
the production of chlorine and bleaching-powder for the textile
industries. To this day, soda manufacture and its allied in-
duction may be considered the foundation of all chemical
technology, of which the beet-sugar process is the first example
of the production in bulk of an organic compound by a com-
plicated series of steps which could never be carried on suc-
cessfully on a small scale. Up to the end of the eighteenth
century, chemicals were made by the pound, since then by
the ton.

Of course, many other causes have succeeded this political
impetus as stimulants to chemical industry: — mechanical
inventions, in connection with the employment of steam as
a motive power; the influence of railroads and steamships in
facilitating the collection of raw materials and finished pro-
ducts; the discovery of great ore-bodies, of petroleum fields
and vast coal-beds; finally, the conversion of mechanical

164 MORRIS LOEB

force into electricity, whereby water-power, the next deriva-
tive of solar energy, becomes available as a constant source
of light, heat and chemical action.

Coal, petroleum, natural gas and ores have accumulated
within the earth's crust for untold ages. Mankind commenced
to draw upon this supply during the past hundred years and
is already considering anxiously its approaching exhaustion.
Chemistry, which has played the leading part in this sudden
increase of consumption, is largely concerned in the effort to
restore the balance which has been disturbed.

With justifiable confidence, we pin our faith upon the
progress of scientific discovery and invention. We should not,
however, do this blindly, but seek to estimate our present
accomplishments at their true value. This is what I have set
out to do in the present volume;1 not, indeed, with the hope of
presenting an exhaustive treatise, but of stimulating thought
in this direction and of leading to a closer inquiry into the
steps by which legislation might differentiate the industries
which promote from those which might endanger the public
good.

For this purpose, I intend to follow up the ramifications of
the chief industries affected by chemical research and attempt
to trace their influence upon human welfare, partly by ascer-
taining what facilities they have afforded, partly by esti-
mating what consumption of energy they have entailed, and
partly by showing what older industries they have displaced
or effaced. . . .

Local conditions, legislation, trade and labor combina-
tions have so much more effect upon wages and living-con-
ditions of the laborer, than has the progress of technical
science, that this subject may be deemed outside of the pre-

1 One cannot but feel poignant regret that the rest of the volume was never
written. [EDITOR.]

CHEMISTRY AND CIVILIZATION 165

sent field. The sanitary side of factory-life must, however, be
considered, from time to time, since it is indeed important to
know whether we are enjoying certain luxuries and comforts
at the risk of life and happiness of our fellow-men; we must
surely count the cost of human life as seriously as the ex-
penditure of fuel and horse power.

In most chemical industries, even taking into account
special risks from poisoning and explosions, hygienic condi-
tions are probably above the average factory standard. In
Germany and other enlightened countries, intelligent legisla-
tion regarding sanitation and employers' liability has won-
derfully diminished those "unavoidable accidents" which
crowd the American news columns, and has reduced the
toll in deaths, sickness and lessened vitality, which unfet-
tered industrial competition still exerts in our own country.
Excepting in a direct tussle with nature, there should
be far fewer really hazardous occupations; certainly, the
dangers connected with chemical manufacture are so
well known that the proper precautions should be readily
available.

On the other hand, it will hardly be profitable to estimate
accurately the question of the influence of chemical manufac-
ture in accelerating the much-deplored flow of rural popula-
tion to the cities. Doubtless, every factory attracts an addi-
tional force of laborers, and the aggregate pay-rolls of chemi-
cal factories must contain an enormous number of potential
farmers. For instance, it has been said of the beet-sugar
factories that they constitute the most natural transition
from farm to factory work; a statement which is apt to be con-
tradicted by those who have seen farmers' children thronging
the cotton-mills and shoe-factories of New England. It will
be admitted by those who deplore the townward trend, that
chemistry has somewhat atoned for the laborers whom it

166 MORRIS LOEB

has lured away from the farm by its gift of artificial fertilizers
and by the increased market which it has provided for various
farm-products. . . .

[The manuscript ends here, although the essay was evidently not com-
pleted.]

PART II
ORIGINAL EXPERIMENTAL INVESTIGATIONS

UEBER DIE EINWIRKUNG VON PHOSGEN
AUF AETHENYLDIPHENYLDIAMIN1

VON Hrn. Prof. HOFMANN veranlasst, habe ich die Ein-
wirkung des Phosgens auf Aethenyldiphenyldiamin studirt
und bin vorlaufig zu folgenden Result aten gekommen.

Die genannte Base wurde mil fliissigem oder in Benzol
gelostem Phosgen 8-10 Stunden im Einschlussrohr auf
80° erhitzt. Das Rohr zeigte nur geringen Druck, in der
Reaktionsmasse hatte sich viel Anilinchlorhydrat ausge-
schieden; mil Benzol und Aether konnte eine Substanz isolirt
werden, welche aus Alkohol in Krystallen anschoss.

War mehr als 1 Mol. Phosgen auf 2 Mol. Base angewandt
worden, so enthielt das Produkt Chlor, bildete kleine Nadeln
und schmolz bei 110°; es gab bei der Analyse Werthe, welche
auf die Formel: —

stimmen: —

Berechnet: Gefunden:

C 57.31 57.34 pCt.

H 3.58 3.61 "

N 8.35 8.46 "

Cl 21.19 21.54 "

Eine derartig zusammengesetzte Verbindung wird ent-
standen sein nach der Gleichung: Ci4Hi4N2 + 2COC12 =
2HCl+Ci6H12N2O2.

Stellte sich das Molekularverhaltniss zwischen ange-

1 Vorlaufige Mittheilung. Berichte d. deutsch. chem. Gesellsch. [hereafter desig-
nated as Berichte] 18, 2427 (1885). Aus dem Berl. Univ.-Laborat. No. ocn. Ein-
gegangen am 15. August.

170 MORRIS LOEB

wandter Base und Phosgen auf 4 : 1, so wurden chlorfreie, bei
115.5° schmelzende, derbe Nadeln oder facherformig ange-
ordnete Blattchen aus Alkohol erhalten, deren Analyse auf
einen Harnstoff der Formel CO. (Ci4Hi3N2)2 deutet.

Mit der genaueren Untersuchung der genannten Produkte,
sowie mit den Studium der Einwirkung des Phosgens auf
Guanidine und Urethane bin ich noch beschaftigt.

UEBER AMIDINDERIVATE l

VOR einiger Zeit 2 habe ich iiber einen Kb'rper berichtet,
welcher durch Einwirkung uberschussigen Phosgens auf
das Aethenyldiphenyldiamin entsteht, und welchem ich,
auf Analysen gestiitzt, die Formel —

zuschrieb.
.N(C6H5) . COC1

Ich habe seitdem diese Annahme durch Darstellung eines
entsprechenden Esters bestatigen konnen; zur Bildung an-
derer Derivate [234 1] war bei der Bestandigkeit jenes Korpers
leider nicht zu gelangen. Schon bei der Darstellung und
Reinigung des Chlorides ist es geboten, eine Temperatur von
60° nicht zu ubersteigen, wenn man eine Ausbeute, die bei
niedriger Temperatur 60 pCt. betragen kann, nicht erheblich
verringern will.

Von kochendem Wasser wird das Chlorid nicht angegriffen,
von Sauren und Alkalien dagegen in das Amidin zuriickver-
wandelt; mit siedenem Alkohol liefert es Carbanilid, Essig-
ester und Chloraethyl.

C16H12N2C12O2 + 3 C2H5OH=

Bei der Darstellung eines Esters muss jede Erwarmung
vermieden werden. Natrium (2 Atome) wurde in Aethylal-
kohol gelost, und nach dem Erkalten die alkoholische Losung
des Chlorides (1 Molekiil) allmahlich unter Abkiihlung
hinzugesetzt. Von dem sich sofort abscheidenden Kochsalz

1 Aus dem Berl. Univ.-Laborat. No. DCLII, Berichte, 19, 2340 (1886). Ein-
gegangen am 14. August.

2 Berichte, 18, 2427 (1885) (page 169 of this book).

172 MORRIS LOEB

abfiltrirt und Uber Schwefelsaure im luftleerem Raume
verdunstet, hinterliess die Fliissigkeit eine chlorfreie Sub-
stanz, welche nach zweimaligem Umkrystallisiren aus
Aether harte, glanzende, rhombische Krystalle bildet, die bei
90.5° schmelzen. In alkoholischer Losung ist sie auch in der
Kalte wenig bestandig. Sie besitzt die Formel

C2H5O.CO.N— C = : =

C2oH22N2O4 Verlangt: Gefunden:

I II III

C 67.79 67.74 pCt.

H 6.21 6.84

N 7.91 8.51 8.60 '"

Derselbe, oder ein ahnlicher Korper stand bei der Behand-
lung des Amidins mit ChlorkohlensaureSthylester zu erwar-
ten. Eine Einwirkung findet jedoch erst bei 60° statt; nach
Verdunsten der vom salzsauren Amidin befreiten Fliissig-
keit verbleibt eine halbfeste Masse, welche an Aether kleine
Mengen eines nicht krystallisirenden Oeles abgiebt, und im
Uebrigen aus Carbanilid besteht.

Sowohl das Chlorid als der Ester werden durch Erhitzen
mit wasserigem Ammoniak in das Amidin zuruckgefiihrt.
Alkoholisches Ammoniak wirkt wie reiner Alkohol. Wird
das Chlorid in Benzol gelost, und trockenes Ammoniakgas
hindurch geleitet, so scheidet sich die theoretische Menge
reinen Salmiaks aus. Die Losung enhalt Aethenyldiphenyl-
diamin. Die Umsetzung muss also folgendermaassen ver-
lauf en sein : —

Ci6H12N2O2Cl2 + 4 NH3=Ci4H14N2 + 2 NH4C1 + 2 HNCO.

Analog entstehen mit heissem Anilin das Amidin, salz-
saures Anilin und Carbanilid. Da such nun eine Amidover-

UEBER AMIDINDERIVATE 173

bindung aus dem [2342] Chlorearbonylderivate des Amidins
nicht darstellen liess, bemiihte ich mich eine directe Anlager-
ung von Cyansaure resp. Rhodanwasserstoff an das Amidin,
welche zu ahnlichen Korpern gefiihrt hatte, zu bewerkstelli-
gen. Auch diese Versuche schlugen fehl, da das Cyanat des
Amidins schon in kalter, wasseriger Lb'sung Kohlensa'ure
und Ammoniak abspaltet; das Rhodanat, welches ein Harz
darstellt, ist zwar bestandiger, lagert sich jedoch nicht in
den Thioharnstoff um, sondern verwandelt sich oberhalb
100° in ein ubelriechendes Oel.

Aethenylimidobenzanilid. Wird das oft erwahnte Chlorid
iiber seinen Schmelzpunkt erhitzt, so tritt bei 150° eine
reichliche Entwickelung von Phosgen ein. Es schien nicht
unwahrscheinlich, das sich unter den Umstanden der Korper

bilden wiirde.

Allein das stete Abspalten von Phenylcyanat verhinderte
mich denselben hierbei zu isoliren. Es ist mir aber gelungen,
ihn auf andere Weise darzustellen. Er entsteht namlich,
wenn Phosgen in Benzol gelb'st, auf einen Ueberschuss von
Aethenyldiphenyldiamin bei 80° einwirkt, oder wenn es als
Gas durch eine siedende Chloroformlosung des letzteren
geleitet wird. Er ist in Aether, Alkohol, Chloroform und
Benzol loslich, und krystallisirt besonders aus letztgenanntem
Losungsmittel in grossen glanzenden Tafeln vom Schmelz-
punkt 118°.

Die Formel Ci5Hi2N2O wird durch die Analyse bestatigt.

Verlangt:

Gefunden:

I

II

Ill

IV

C 76.27

77.33

76.61

—

pCt.

H 5.08

5.62

5.60

—

«

N 11.85

—

—

11.73

12.07 "

174 MORRIS LOEB

Diese Substanz ist identisch mil derjenigen, welche ich
friiher1 erwahnt und damals als bei^l!5.5° schmelzend an-
gefiihrt habe. Ueber den Schmelzpunkt erhitzt braunt sich
das Aethenylimidobenzanilid bald, und entwickelt etwas
Isonitril. Mit verdiinnter Salzsaure gekocht spaltet es sich
vollkommen, wobei Anilin und Phenylcyanat auftreten: —

C16Hi2N2O + 2H2O=C6H5NH2 + CeHsNCO + C2H4O2.

Versuche tiber die JSinwirkung von Phosgen auf Benzenyl-
diphenyldiamin fiihrten zu keinem Ziele, da die Reaktions-
producte allzu geringe Krystallisationsfahigkeit zeigten; die
schwierige Darstellung und geringe Haltbarkeit der meisten
in der Literatur verzeichneten [2343] Amidine hielten mich
da von ab, die nicht besonders ergiebige Untersuchung auf
solche auszudehnen. Dagegen habe ich aus dem Cyananilin

CeHsNHC : NH

Hof mann's 2 I welches sich als Diphenyloxal-

: NH

amidin auffassen lasst, durch Einwirkung von Carbonyl-
chlorid einen krystallinischen Korper erhalten, auf welchen
ich spater zuriickzukommen hoffe.

Ich mochte hier noch iiber einen Versuch berichten, Cyan
an Aethenyldiphenyldiamin anzulagern. Eine gesattigte
atherische Losung von Aethenyldiphenyldiamin, mit 2-3
Tropfen Wasser versetzt, farbt sich beim Durchleiten von
Cyangas allmahlich dunkel. Unterbricht man das Einleiten,
sobald die Fliissigkeit weinrot geworden, und lasst sie unge-
fahr 16 Stunden stehen, so ist sie noch bedeutend nach-
gedunkelt und der Geruch des Cyans demjenigen der Blau-
saure gewichen. Zuweilen haben sich auch schwarze Krusten
an den Wanden des Gefasses abgesetzt. Von diesen wird

1 Berichte, 18, 2427 (1885) (page 169).

2 Hofrnann, Liebigs Annalen, 66, 129 (1848); 73, 182 (1850).

UEBER AMIDINDERIVATE 175

abfiltrirt, der Aether bei moglichst niedriger Temperatur
verdunstet und der klebrige, braune Riickstand mil kaltem,
verdiinnten Alkohol vom farbenden Harze befreit. Das ver-
bleibende, weisse, krystallinische Pulver, welches zwischen
Filtrirpapier moglichst abgepresst und iiber Schwefelsaure
getrocknet wird, lost sich sehr schwer in kaltem Aether und
Benzol. Es lasst sich nicht umkrystallisiren, da es beim
Erhitzen in Losungsmitteln rasch verharzt; mit Alkohol
benetzt, zersetzt es sich sogar schon an der Luft, In reinem
Zustande schmilzt es unter Zersetzung bei 165°, wird jedoch
schon gegen 120° violett und dann braun.

Die Analyse ergiebt Zahlen, welche sich auf einen Korper
Ci6Hi6N4O beziehen lassen.

Verlangt: Gefunden:

I II III IV V

C 68.57 68.24 68.52 68.6 pCt.

H 5.71 5.24 5.84 6.21 "

N 20.00 19.55 20.32

Diese Formel lasst sich am einfachsten nach dem Vorbild
von Griess' Cyancarbimidoamidobenzosaure 1 und von
Bladins Cyanphenylhydrazinderivaten 2 in folgender Weise
deuten: —

CH3 . C . N . C . CN

II I \\ +H2O.
C6H5 . N . C6H5 NH

Ich gedenke den Korper weiter zu untersuchen. [2344]

Zum Schlusse mag hier noch ein Versuch Erwahnung
finden, welchen ich im Laufe der Arbeit iiber Phosgen mit
Urethan angestellt. Urethan (7 Theile) und Phosgen (1
Theil) in Benzol gelost, wurden im Rohr auf 75° erhitzt.
Beim Oeffnen der Rohren entwich viel Salzsaure und das
Benzol enthielt eine chlorfreie Substanz, welche beim Um-

i Berichte, 11, 1985 (1878). 8 Berichte, 18, 1544 (1885).

176 MORRIS LOEB

krystallisiren aus Alkohol oder Chloroform langsam den
Schmelzpunkt 194° erreichte. Analysen und Umwandlung
in Biuret bewiesen, dass Allophansaureathy Jester vorlag;
selbiger kann entweder nach der Gleichung

2 NH2COOC2H5 - NH2CONHCOOC2H5 +C2H5OH

entstanden sein, oder es hat sich intermediar Carbonyldiure-
than CO(NHCOOC2H6)2 gebildet, welches beim Umkrystal-
lisiren zerfallen ist. Aehnliche Versuche iiber die Einwirkung
des Phosgens auf Alanin fiihrten zu keinem Resultate.

DAS PHOSGEN UND SEINE ABKOMMLINGE

NEBST EINIGEN BEITRAGEN ZU DEREN

KENNTNISS 1

GESCHICHTLICHES

SELTEN hat sich wohl ein erbitterter Streit fiir die Chemie
segensreicher erwiesen, als jener, welcher am Anfang unseres
Jahrhunderts iiber die Annahme der Unzerlegbarkeit des
Chlors entbrannt ist. Es war nicht nur der Fortschritt,
welchen der endliche Sieg von Davy's chloristischer Theorie
durch die Beseitigung mancher hemmender Hypothesen mit
sich brachte: auch in materieller Hinsicht haben wir dieser
Discussion viel zu verdanken. In dem Eifer, gegen eben-
blirtige Gegner neue Argumente zu erlangen, ward gar
manche Thatsache entdeckt, die sonst wohl lange unbekannt
geblieben ware, die uns aber heute von erster Wichtigkeit
erscheint. Eines der besten Beispiele liefert das Phosgen,
dessen Erkennung eine inter essante Episode in jenem Streite
bildete.

Als Humphry Davy 2 im Jahre 1811, seine Ansicht entwick-
elte, dass jenes Gas, welches man bisher als oxydirte Salz-
saure aufgefasst, ein einfacher Korper sei, und ihm den Namen,
"Chlorine" beilegte, gait unter seinen Landsleuten Dr.
John Murray, der Lieblingsschiiler Black's, als berufenster
und eifrigster Verfechter der alteren Ansicht. Nachdem
Ersterer seiner besten Argumente durch die Beweiskraft
Davy'scher Experimente verlustig gegangen war, glaubte er

1 Inaugural-Dissertation zur Erlangung der Doctorwfirde von der Philosophischen
Facultat der Friedrich-Wilhelms-Universitat zu Berlin. 15. Marz, 1887. [Printed
by C. Berg, Berlin, 1887.]

2 H. Davy, Bakerian Lecture, Phil. Trans. 1811, p. 1.

178 MORRIS LOEB

seinerseits in einigen neuen Beobachtungen eine schlagende
Waffe gefunden zu haben.

[2] Er hatte Kohlenoxyd und Chlor im Sonnenlichte zu-
sammenstehen lassen, und gab nun Ammoniak hinzu,
worauf eine bedeutende Volumverminderung folgte. Da
nun Zusatz starker Salpetersaure zu der entstandenen
Salzlosung eine Kohlensaureentwickelung hervorbrachte,
f olgerte Murray, dass die Losung salzsaures und kohlensaures
Ammoniak enthalte, was dadureh zu erklaren sei, dass, die
"oxydirte Salzsaure" zerf alien und das Kohlenoxyd im
freigewordenen Sauerstoff verbrannt waren. Um dieses
wichtige Argument womoglich zu entkraften, wiederholte
John Davy,1 der seinen beriihmteren Bruder untersttitzte,
diese Versuche und fand zu seiner Genugthuung, dass sich
Chlor und Kohlenoxyd zu einem definirten Gase vereinigen,
das weder Salzsaure noch Kohlendioxyd zu liefern vermag,
wenn nicht anwesende Feuchtigkeit den nothigen Wasser-
stoff und Sauerstoff liefert. Wenn dasselbe mit trocknem
Ammoniak vermischt werde, so enthalte das entstehende Salz
keine Kohlensaure, da Essigsaure solche nicht daraus aus-
treibe. Nur beim Zusatz starker Mineralsauren enstehedurch
Wasserassimilation Kohlensaure.

Diesem Argumente war Murray nicht mehr gewachsen;
jenes neue Gas aber nannte John Davy, da es unter der
Einwirkung des Sonnenlichtes entsteht, Phosgen und be-
trachtete es als eine Saure, welche vier Aequivalente Ammo-
niak zur Sattigung verlange. Erst 1838 gelangte Regnault2
zur Ueberzeugung, dass Ammoniak und Phosgen nicht ein
einheitliches Salz bilden, sondern ein Gemisch von Salmiak
und "Carbamide" Obwohl letzteres dieselbe Zusammen-

1 John Davy, Philosophical Transactions of the Royal Society, 1812, p. 144.
Nicholson's Journal of Natural Philosophy and Chemistry (London und Edinburgh)
30, 28. Die ganze Controverse fand in diesem Journale statt, in den Banden 27-34.

2 Regnault, Ann. de Chim. et Phys. 69, 180 (1838).

DAS PHOSGEN 179

setzung mil Harnstoff habe, sei es doch nicht damit identisch,
da noch so concentrirte Losungen die charakteristische
Fallung mit Salpetersaure nicht gaben. Er schrieb vielmehr
dem "Carbamide" [3] die halbe Molekularformel des Harn-
stoffes zu. Natanson1 jedoch, der das Carbamid sorgfaltiger
reinigte, erhielt ohne Miihe den salpetersauren Niederschlag
der zur Identifizirung der beiden Substanzen noch fehlte.
Die Reaktion verlauft also in folgender Weise: —

Natanson schrieb Regnaults Unvermogen, den besprochenen
Niederschlag zu erhalten, dem Umstande zu, dass die Gase
nicht geniigend getrocknet waren, weshalb ein so grosser
Ueberschuss an Salmiak entstanden, dass das Carbamid
nur schwer davon befreibar war. Thatsachlich ist aber die
Verunreinigung auch noch darin zu suchen, dass nach Bou-
chardat 2 und Fenton 3 die Reaktion nie glatt verlauft, son-
dern als Nebenprodukte noch Guanidin-, Cyanursaure und
Melanurensaure auftreten. An besonderer Bedeutung
gewann aber Regnaults Reaktion durch Hofmann,4 der am
Anilin zeigte, dass sie auch auf die Amine ausdehnbar sei.

Noch vor Regnault hat Dumas sich mit dem Phosgengas
beschaftigt, und zwar ist es seine wichtige Reaktion mit den
Alkoholen, welche er 1833 5 in voller Klarheit auseinander-
setzte. Das Warum und das Wie entnehme ich der schonen
Schilderung, welche mein verehrter Lehrer von Dumas
Leben und Wirken entworfen hat.6

"Der Analyse nach liess sich der Zucker als eine Ver-

1 Natanson, Liebigs Annalen [hereafter designated as Annalen] 98, 287 (1856).

2 Bouchardat, Comptes Rendus, 69, 962 (1869).

8 Fenton, J. Chem. Soc. 35, 793 (1879) . Der Auszug im Jahresbericht 1879, ist darin
unrichtig, dass es F. Bouchardats Erfahrungen nicht widerspricht: dasVorhandensein
von Guanidin bestatigt er; nach den andern Nebenprodukten hat er nicht gesucht.

4 Hofmann, Annalen, 67, 267 (1846). 6 Dumas, Annalen, 10, 277 (1834).

6 Hofmann. Nekrolog auf Dumas, Ber. deutsch. ch. Ges. 17 (1884), Ref. 662 ff.

180 MORRIS LOEB

bindung von Alkohol und Kohlensaure auffassen, und diese
[4] Auffassung schien in der Spaltung des Zuckers durch den
Gahrungsprozess eine Bestatigung zu finden. Allerdings war
es nicht gelungen, durch direkte Vereinigung von Alkohol
und Kohlensaure Zucker zu erzeugen. Allein konnte man
hoffen, dass sich diese Vereinigung wiirde bewerkstelligen
lassen, wenn man dem Alkohol die Kohlensaure in condicione
nascendi bote. Diese Betrachtung veranlasste Dumas, die
Einwirkung des Phosgengases auf den Alkohol zu studiren.

"Er hoffte eine Verbindung zu erhalten, welche, mit
Wasser behandelt, Salzsaure und Kohlensaure liefern wiirde
und, wenn letztere mit dem Alkohol in Verbindung blieb,
Zucker erzeugen konnte. Diese Hoffnung ist allerdings un-
erfiillt gebleiben, aber der Versuch hat zur Entdeckung des
Chlorkohlensaure-Aethers gefiihrt, welcher unter dem Ein-
flusse des Ammoniaks in Urethan oder Carbaminsaure- Aether
iibergeht. Die Zusammensetzung, welche Dumas fiir diese
beiden typischen Verbindungen feststellte, ist die noch heute
anerkannte; aber wie viele Entdeckungen sind seitdem von
den Chemikern auf dem von ihm erschlossenen Gebiete ge-
macht worden, und welche Ernten verspricht auch heute
noch die Bebauung derselben, zumal seit die neueste Schwen-
kung der Farbenindustrie das ehedem nur schwierig zugang-
liche Phosgengas verfliissigt der Forschung in beliebiger
Menge zur Verfiigung stellt."

Was nun, seit jenen frtihen Tagen, zur Kenntniss des Phos-
gens und seiner Abkommlinge beigetragen worden, und welche
Ansichten die Nachfolger Davys, Regnaults und Dumas
geleitet, das hoffe ich im Folgenden geordnet darzuthun.

DARSTELLUNG

Zur Darstellung des Phosgens im Grossen dient noch
immer die Methode Davys, gleiche Volume Kohlenoxyd und

DAS PHOSGEN 181

Chlor den Sonnenstrahlen auszusetzen. Die Vereinigung er-
folgt rasch, und kann man, wenn man mit grossen Gefassen
[5] arbeitet, das Gas durch Abkiihlung verfliissigen und so
auffangen, bei kleineren Quantitaten leitet man das Gas in
Losungsmittel ein. Una die grossen Glasgefasse und die
Nothwendigkeit der Belichtung zu vermeiden, hat man auch
haufig Hofmann's Darstellungsmethode 1 vorgezogen, bei
der man Kohlenoxyd zur Chlorirung Uber siedendes Anti-
monpentachlorid leitet. Paterno 2 will die directe Vereini-
gung des Kohlenoxyds mit Chlor dadurch bewirken dass
er die Gase uber Knochenkohle leitet. Es giebt noch viele
Vorschlage, das Phosgen durch Oxydation von Tetrachlor-
kohlenstoff 3 oder Chloroform 4, oder durch Wechselwirkung
derselben mit Kohlenoxyd 5 darzustellen. Da aber die Ent-
stehung lastiger Nebenprodukte unvermeidlich ist, und auch
die angewandten Substanzen haufig von erschwerender
Beschaffenheit sind, hat sich keines dieser Verfahren ein-
blirgern konnen.

Wahrend diese Methoden alle eine Synthese des Phosgens
aus seinen Bestandtheilen bedeuten, sind einige noch aus
theoretischen Griinden bemerkenswerth, da sie in einem
Abscheiden des Phosgens aus komplizirteren Verbindungen
bestehen und gerade deshalb neuerdings anscheinend wieder
hervorgeholt werden.

Schon Berzelius 6 hatte entdeckt, dass durch Einwirkung
feuchten Chlorgases auf Schwefelkohlenstoff eine Substanz
entsteht, die mit Schwefelsaure behandelt Chlorkohlenoxyd

1 Hofmann, Annalen, 70, 139 (1849).

2 Paterno, Gazzeta Chimica Italiana, 8, 233 (1878).

3 Gustavson, Zeitschrift fur Chem. 1871, 615. SchUtzenberger, Compt. Rend. 66,
747 (1868).

4 Dewar und Cranston, Chem. News, 20, 174 (1869). Emmerling und Lengyel,
Berichte, 2, 547 (1869).

6 SchUtzenberger, Compt. Rend. 66, 747 (1868).
6 Berzelius und Marcet, Gilbert's Annalen, 48, 161.

182 MORRIS LOEB

abspaltet. Kolbe 1 verdanken wir die Bestatigung und [6]
nahere Erklarung dieser Reaktion, die nach den heutigen
Formeln folgendermassen verlauft: —

I. CS2+4Cl2+m2O=CCl3SO2Cl+4HCl

Trichlonnethyl
sulfonsaurechlorid

II. CC13S02C1+H2O = COC12 + SO2+2HC1
Noch leichter lasst sich das Phosgen aus Dichlormethyl-
sulfonsaurechlorid abspalten, indem dasselbe sich an der
Luft oxydirt.

CHC12SO2C1+O= COC12+HC1+SO2

Kolbe fand auch dass das trockene Natriumsalz der Tri-
chloressigsaure beim Erhitzen Phosgen liefert

CCl3COONa = CO C12 + CO + NaCl

Perchlorameisensauremethylester lasst sich als Polymer
des Chlorkohlenoxids auffassen und zerf allt auch beim Durch-
streichen auf 340-350° erhitzter Rohren in dasselbe2

CC10.OCC13 = 2COC12.

Auch verhalt sich der Ester Reagentien gegeniiber dem
Phosgen analog. Ebenso scheint Schiitzenbergers 3 Carbonyl-
chloroplatinit PtCl2.CO mit Leichtigkeit in Platin und
Phosgen zu zerfallen, und konnte wohl manchmal da niitz-
lich sein, wo ein fester Aggregatzustand der Reagentien wiin-
schenswerth erschiene.

BESCHBEIBUNG

Wir kennen das Phosgen als ein farbloses erstickend
riechendes und die Schleimhaute heftig angreifendes Gas,
welches bei gewohnlichen Drucke erst unter 0° C. condensirt

1 Kolbe, Annalen, 64, 148 (1845).

2 Cahours, Ann. de Chim. et Phys. [3], 19, 352 (1847).
1 Schutzenberger, Jahresbericht, 1870, 381.

DAS PHOSGEN 183

wird, obwohl sein Siedepunkt bei 8.2° liegt.1 Die Fliissig-
keit besitzt bei 0° das specifische Gewichte 1.432.

[7] Es ist in Aether, Chloroform, den flussigen Kohlen-
wasserstoffen, Schwefelkohlenstoff und Chlorschwefel, sowie
in den fliissigen Metallchloriden, sehr leicht loslich. Nach
Berthelots Beobachtung 2 nimmt das Benzol bei sinkender
Temperatur immer grossere Mengen des Phosgens auf,
bis beim Gefrierpunkte des Benzols das sich verflussigende
Phosgen seinerseits als Losungsmittel fungirt. Da diese
Loslichkeit von keiner chemischen Wirkung bedingt ist und
sich die beiden Substanzen unter den meisten Umstanden
indifferent zu einander verhalten, wird das Phosgen vielfach
in Benzollosung angewandt, besonders auch wegen der
Moglichkeit genauen Abwagens.

Von Wasser wird Phosgen in der Kalte langsam, in der
Wa'rme rasch zerlegt, wobei sich Salzsaure und Kohlendioxid
bilden und viel Wa'rme frei wird.3 Zur quantitativen gaso-
metrischen Bestimmung des Phosgens hat Berthelot4 eine
sehr charakteristische Methode ersonnen, welche auf der Ver-
dreifachung seines Volums beim Einbringen feuchten Na-
triumbicarbonats beruht

COCl2+2NaHCO3 - 3CO2+2NaCl+H2O

1 Vol. 8 Vol.

Da das Phosgengas so leicht aus Kohlenoxyd und Chlor
entsteht, ware es zu erwarten, dass ohne allzugrosse Schwie-
rigkeit auch Jod, Brom und Cyan zum Vereinigen mit Koh-
lenoxid zu bringen waren. Im Gegentheil lasst sich Brom-
kohlenoxyd nur schwierig durch Oxydation des Bromof orms

1 Emmerling und Lengyel, Annalen, Suppl. 7. 105 (1868-1870).

2 Berthelot, Annalen, 166, 228 (1870).

8 Nach Berthelot (Annales [5] 7, 129) (1879) entstehen bei der Reaktion COC12-H
H2O+Ag = CO2Ag+HClAg,+65600 cal.; nach Thomsen (Berichte, 16, 2619)
(1873) 57970 cal.

4 Berthelot, Annalen, 156, 228.

184 MORRIS LOEB

erhalten1 und ist eigentlich noch nie ganz rein dargestellt und
beschrieben worden.

Das Jodphosgen hat man iiberhaupt noch nicht zu Stande
gebracht.2 [Auf das Cyankohlenoxyd ist schon vielfach [8]
gefahndet worden, da es nicht nur wegen seiner Analogic
mit dem Chlorkohlenoxyd, sondern auch als Nitril einer zwei-
basischen Ketonsaure Interesse geboten hatte. Es sind wohl
in der Litteratur verschiedene Notizen zu finden, welche
iiber fehlgeschlagene Versuche berichten und neue ankiin-
digen;3 da jedoch iiber die letzteren nie berichtet wurde,
kann man wohl annehmen, dass auch sie resultatlos verlaufen
sind.

Dagegen ist neuerdings die Existenzf ahigkeit des Chlorcyan-

,C\

kohlenoxyds OCX als eines dem Phosgen sehr ahnlichen

'XCN,

Gases ausser Frage gestellt. Indem Bauer4 im Laufe einer
Untersuchung chlorirter Nitrile, Bromwasserstoffgas auf
Dichlormethoxyacetonitril einwirken liess, erhielt er neben
Brommethyl nur noch einen festen Korper, welcher sich beim
Erhitzen unter theilweiser Verkohlung in ein schweres scharf-
riechendes Gas verwandelte, dessen Zersetzungsprodukt es
mehr als wahrscheinlich machte, dass Chlorcyankohlenoxyd
vorliege. Die Reaktion hatte mithin den Verlauf genommen

CH3O.CC12.CN + HBr - HO.CC12CN + CH3Br.

Bauer vermuthet dass dieser Korper unbestandig sei
und sof ort die Zersetzung in Salzsaure und Chlorcyankohlen-
oxyd erleide.

1 Emmerling, Berichte, 13, 873 (1880).

2 Cowardins, Chem. News, 48, 97 (1883).

8 So Carstanjen und Schertel, Journ. prakt. Chem. [2], 4, 49 (1871). GintI, ibid.,
362.
4 Bauer, Annalen, 229, 187 (1885).

DAS PHOSGEN 185

/CN
HO.CC12.CN = O : C< + HC1

Dass das Phosgen vielf ach als Analogon des Kohlendioxids
und Kohlenoxysulfids zu betrachten ware, erhellt sowohl
aus seiner Bildungsweise, als aus den Thatsachen dass manche
[9] seiner Derivate mit derselben Leichtigkeit aus letzterem
erhalten werden konnen, wa'hrend es sich selber bei vielen
Reaktionen in ersteres umwandelt. Dagegen ist schon friih
beobachtet worden, dass in Fallen wo man seine beiden
Chloratome successive ersetzen wollte, das zweite Chloratom
sich viel bestandiger verhielt als das erste. Durch blosses
Zusammenbringen von Chlorkohlenoxyd und Alkohol wird
ein Chloratom ausgewechselt und es entsteht der Ester der
Chlorameisensaure. Dagegen ist erhohte Temperatur,
langeres Stehen oder dergleichen nothig, um auch das zweite
Chloratom zum Austritt zu bewegen. Um dies zu betonen,
fasst man das Phosgen gerne als Chlorameisensaurechlorid
auf: es gab sogar eine Zeitlang ernstliche Meinungsunter-
schiede, da Manche sich die beiden Chloratome in verschie-
dener Weise im Molekiil functionirend dachten. Schreiner 1
glaubte gar diese Verschiedenheit in den Derivaten wieder
finden zu konnen und behauptete, dass, wenn er aus Phos-
gen und Methylalkohol bereiteten Chlorameisensaure-Me-
thylester mit Natrium-Aethylat behandelte, das Produkt
verschieden sei von dem gemischten Ester aus Chlorameisen-
saure- Aethylester und Natrium-Methylat. Eine griindlichere
Untersuchung von Roese2 erwies jedoch diese Idee als
nichtig.

Die heutige Auffassung der Zustande in Molekiil macht
aber auch ein Disput iiber diese Frage inhaltslos. Es wiirde

1 Schreiner, Journ. prakt. Chem. [2], 22, 353 (1880).

2 Roese, Annalen, 205, 227 (1880).

186 MORRIS LOEB

von gedankenloser Gewohnung an das rein Aeusserliche der
graphischen Formeln zeugen, miissten wir uns immer erst
klar machen, dass in den Saurechloriden auch das Chlor
direkt mit dem Kohlenstoff verbunden ist, so dass kein Unter-
schied besteht zwischen

/Cl Cl
OC< und |
XC1 COC1

[10] Ernstlich eine Constitution anzunehmen

/Cl

c<

XOC1)

wiirde uns zum zweiwerthigen Kohlenstoff fiihren und ware
durch die Constitution von keinem der Derivate zu begriin-
den. Bleiben wir also bei der herkommlichen Formel des Phos-
gens und denken wir uns keine verschiedene Bindekraft des
Kohlenoxyds f iir die beiden Chloratome : alsdann kb'nnen wir
getrost die Ursache der grosseren Bestandigkeit der Chlor-
ameisensaureester darin suchen, dass, nachdem beim ersten
Zusammenstoss der Molekiile ein Chloratom durch die Alk-
oxyl-Gruppe ersetzt worden, nunmehr ein derartiger Gleich-
gewichtszustand zwischen den positiven und negativen
Principien im Molekiil eingetreten ist, wie wir ihm sonst
haufig begegnen. Denkt man sich z. B. die Schwefelsaure
etwa unsymmetrisch constituirt, weil Benzolsulfonsaure eine
bestandige Verbindung ist, und nicht bei der Darstellung in
Sulfobenzid iibergeht?

ABKOMMLINGE

Die Einwirkung des Phosgens auf anorganische Substanzen
bietet kein Interesse: es wirkt entweder unter direkter Ab-
gabe seines Chlors oder unter Austausch desselben gegen

DAS PHOSGEN 187

Sauerstoff. Auch unter den kohlenstoffhaltigen Korpern
giebt es manche, auf die es genau wie Phosphorpentachlorid
reagirt. So fand Kempf1 dass Benzaldehyd in Benzalchlorid,
Aceton in Dichloraceton, Essigsaure in Acetylchlorid ver-
wandelt wird. Neuerdings soil aus letzterer Reaktion mit
gutem Erfolge die technische Anwendung gezogen werden,
dass man, behufs Bildung der Saureanhydride, Phosgengas
in die erhitzten Sauren oder deren Salze leitet.2

[11]

I. CH3COONa+COCl2 = CH3COCl+CO2+NaCl
II. CH3COONa+CH3COCl = (CH3CO)2O+NaCl.

Die Reaktion zwischen Phosgen und Aldehyd war Gegen-
stand eines merkwiirdigen Irrthums, welcher auf die chemische
Theorie einigen Einfluss haben musste und dessen Beseitigung
wir Kekule und Zincke verdanken. 1858 beschrieb Harnitz-
Harnitzky 3 einen Korper, " Chloraceten " durch Einwirkung
von Chlorkohlenoxyd auf Aldehyddampf entstanden. Das-
selbe habe einen konstanten Siedepunkt, sei bei gewohnlicher
Temperatur fliissig, bei 0° krystallinisch fest. Analysen und
Dampfdichte Bestimmung ergaben die Formel C2H3C1,
welche jedoch auch dem Vinylchlorid zukomme, von dem
das Chloraceten sehr verschieden sei. Da die Constitution

des Vinylchlorids ohne Zweifel CH2=CHC1 ist, musste das

ii

Isomer, aus Aldehyd entstanden, CH3-C— Cl sein. Das
zweiwerthige Kohlenstoffatom erweckte Interesse. Friedel,4
Kraut,5 Stacewitz 6 stellten den Korper nach Harnitz-Har-
nitzkys Angaben dar und machten Derivate welche die

Kempf, Journ. praJd. Chem. [2], 1, 402 (1870).

Hentschel, Berichte, 17, 1284(1884).

Harnitz-Harnitzky, Annalen, 111, 192 (1859).

Friedel, Compt. Rend. 60, 930 (1865). Ann. chim. et phys. [4], 16, 403 (1869).

Kraut, Annalen, 147, 107 (1868).

Stacewitz, Zeitschrift f. Chemie (1869), 321.

188 MORRIS LOEB

Constitution erharten sollten. Indem sie aber Harnitz-
Harnitzkys Beschreibung des ' 'Chloracetens " bestatigt
fanden, zweifelten sie auch nicht an der Richtigkeit seiner
Analysen und Constitutionserklarung. Kekule und Zincke 1
theilten jedoch dieses Vertrauen nicht und ihre eingehende
Untersuchung ergab die Nichtexistenz des " Chloracetens."
Sie fanden dass die hierfiir gehaltene Substanz ein Gemisch
von Aldehyd und Phosgen sei,ohne bestimmte Zusammensetz-
ung und ohne Bestandigkeit. Das Phosgen begiinstige die
Entstehung von Paraldehyd, habe aber sonst keine Wirkung.
Die aus " Chloraceten " entstandenen Derivate leiteten sie
theils selber vom unveranderten Aldehyd her, theils ist dies
seither von Andern [12] geschehen. Allerdings wa're zu er-
warten gewesen, dass Aldehyd nach Analogic des Benzalde-
hyds, in Aethylidenchlorid iibergegangen ware

CH3CHO+COC12 = CH3CHC12+CO2.

Dies glaubt auch Eckenroth 2 neuerdings beobachtet zu
haben: da jedoch die diesbeziigliche Angabe nur in einer
kurzen Erwahnung der Thatsache besteht, lasst es sich noch
nicht erklaren, warum das Aethylidenchlorid der genauen
Forschung Kekule und Zinckes entgangen sein soil.

Wenden wir uns nun zu denjenigen Synthesen, in denen
mittels der Carbonylgruppe ein wahrer Aufbau stattfmdet,
so ist die Anzahl der Falle einer direkten Anlagerungan
Kohlenstoff in der Fettreihe etwas beschrankt. Bis vor Kur-
zem hatten wir nur eine ungliickliche Angabe Harnitz-
Harnitzkys 3 dass Kohlenwasserstoffe und Phosgen Saure-
chloride lieferten, welcher Berthelots und dessen Schiller 4

1 Kekul^ und Zincke, Annalen, 162, 125 (1872).

2 Eckenroth, Berichte, 18, 518 (1885). Anmerkung.

» Harnitz-Harnitzky,Com^. Rend. 68, 748(1864). ^nn.136, 121 (1865). Compt.
Rend. 60, 923 (1865).

4 Berthelot, Annalen, 166, 216 (1870). De Clermont et Fontaine, Ibid. 226.
Bull. Soc. Chim. n. s. 13, 9 (1870).

DAS PHOSGEN 189

genauere Untersuchungen alle Glaubwiirdigkeit geraubt
hatten; sodann eine Beobachtung Butlerows,1 dass Zink-
methyl mit Phosgen in Sonnenlichte eine krystallinische
Verbindung abgiebt, welche mit Wasser in Trimethylcar-
binol ubergeht. Nach andern von Butlerow ausgefiihrten
Reaktionen diirfte man sich wohl den Vorgang in folgender
Weise vorstellen : —

I. 2Zn(CH3)2 + COC12 = (CH3)3COZnCH3 + ZnCl2
II. (CH3) 3C.OZnCH3 + H2O = (CH3) 3COH + ZnO + CH4.

Nachdem, man mehrfach vergebens versucht hatte, Chlor-
kohlenoxyd,- analog anderen Saurechloriden, auf Natrium-
acetessigester einwirken zu lassen, haben im vorigen Jahre
Conrad und Guthzeit 2 unter Anwendung des Kupfersalzes
des [13] Acetessigesters ein sehr gunstiges Resultat erzielt.
Das Produkt der Einwirkung ist jedoch nicht, wie erwar-
tet, ein Carbonyldiacetessigester (Diacetylacetondicarbon-
saureester) sondern dessen Dehydroverbindung.

CH3— CO CO— CH3

c*« CH

btatt / \ / \

/ \ / \
/ CO \
COOC2H5 COOC2H5

O

/\t

CH3— C C— CH3

entstand ii jL

/\ /\
/ \/' \

/ (^Q \

COOC2H5 COOC2H5

1 Butlerow, Berichte, 3, 426 (1870).

2 Conrad und Guthzeit, Berichte, 19, 190 (1886).

190 MORRIS LOEB

Es gentigt, diesen Korper mit Ammoniak zu behandeln,
um ein Pyridinderivat zu erhalten, den Dimethyloxypyridin-
dicarbonsaure-Aethylester.

NH

/ \
/* \

CHs — C* C — CHs

ii ii

c c

s\ s\
/ \ /' \
• CO •
COOC2H5 COOC2H5

Die Anwendung eines primaren Amines statt des Am-
moniaks fiihrt zum entsprechenden Substitutionsprodukt
dieses eigenartigen Korpers. Jedenfalls diirfte diese Reaktion
des Phosgens noch bedeutsamer Variirung fahig sein.

In der aromatischen Reihe ist eine unmittelbare Ein-
wirkung des Phosgens auf einen Kohlenwasserstoff nur von
[14] Graebe und Liebermann 1 beobachtet worden. Es ent-
steht bei 200° ein Anthracencarbonsaurechlorid. Behla 2 hat
dies als 7-Derivat erkannt

\COC1

und auch gefunden, dass bei hoheren Temperaturen 77-Chlor-
anthracencarbonsaurechlorid und 77-Dichloranthracen ent-
stehen.

Friedel, Ador und Crafts 3 wussten durch Vermittelung
des Aluminiumchlorids einen sofortigen Eintritt des Car-
bonyls in den Benzolkern zu bewerkstelligen, und erhielten

1 Graebe und Liebermann, Berichte, 2, 678 (1869).

2 Behla, Berichte, 18, 3169 (1885).

8 Friedel, Ador und Crafts, Berichte, 10, 1854 (1877).

DAS PHOSGEN 191

je nach der Dauer der Einwirkung Benzoylchlorid oder Ben-
zophenon,

I. C6H6+COCl2=C6H5COCl+HCl
IT. C6H5COC1+C6H6=C6H5COC6H5+HC1.

Dies Verfahren ist allgemein und 1st nicht nur bei den
Homologen des Benzols, sondern auch in der Thiophenreihe
angewandt worden.

Drittens liess Wurtz l Natrium auf Brombenzol und Phos-
gen einwirken.

C6H5Br+COCl2+Na2 = C6H5COCl+NaBr+NaCl.]

Wenn diese Reaktion auch typisch ist, so hat sie doch in
dieser Form nur einmal Anwendung gefunden; man zieht
vor, das Phosgen durch den verwandten Chlorameisensaure-
Ester zu ersetzen.

Ein viertes Beispiel Synthesen dieser Art wird sich spater
so viel besser besprechen lassen, dass ich nun zur Wirkung
des Chlorkohlenoxyds auf hydroxylhaltige Verbindungen
ubergehe.

[15] Wie schon angedeutet worden ist, entsteht beim Ein-
leiten von Phosgen in einen Alkohol immer der Chlorameisen-
saureester (Chlorkohlensaureester) : wie zum Beispiel bei An-
wendung des Methylalkohols

CH3OH+COC12 = Cl.COOCHs+HCl.

Eine Ausnahme bildet bis jetzt nur das Glycol, dessen
zwei Hydroxylgruppen zugleich in Reaktion tretend, zum
normalen Carbonat ftthren.2 Aus einem Chlorameisensaure-
ester entsteht der neutrale Kohlensaure-Ester erst beim
langeren Stehen oder Erhitzen mit dem Alkohol oder durch
Einwirkung des Natriumalkoholats. Durch Anwendung

1 Wurtz, Comptes Rendus, 68, 1298 (1869).

a Nemirowsky, Journ. prakt. Chem. 28, 439 (1883).

192 MORRIS LOEB

anderer als des urspriinglichen Alkohols kann man zu den
mannigfaltigsten gemischten Estern gelangen. Audi greift
Wasser die Chlorameisensaureester an, unter Bildung von
sauren kohlensauren Estern, welche Alkalien zu verbinden
vermogen. Ferner lasst sich das Chloratom im Chlorameisen-
saureester durch einen Ammoniak- oder Amin-Rest ersetzen.
Dumas, welcher zuerst die Reaktion

2NH3+C1COOC2H5 = NH2COOC2H5+NH4C1

ausfiihrte,1 erkannte sofort, dass der neue Korper zum Harn-
stoff in derselben Beziehung stehe, wie Oxamaethan zum
Oxamid: er wahlte deshalb den Namen Urethan. Es ist dies
der Ester der hypothetischen Carbaminsaure. Wenn Amine
in dieser Reaktion das Ammoniak vertreten, entstehen natiir-
lich Ester substituirter Carbaminsauren.

Es kann als Regel gelten, dass jeder Korper welcher mit
Phosgen reagirt, auch mit dem Chlorameisensaureester eine
entsprechende Verbindung geben muss. Die leichtere Hand-
habung des letzteren, als einer hoher siedenden, geruchlosen
und unschadlichen Fliissigkeit,hat ihmauch zu einer grosseren
Beliebtheit verholfen, so dass die Anzahl seiner Derivate fast
unabsehbar ist. Fur die Wurtz'sche und Friedel und Crafts'-
sche Reaktionen mit Kohlenwasserstoffen, fiir die [16] Dar-
stellung mannigfaltiger Aminsauren und Harnsaurederiva-
ten ist diese Substanz unschatzbar.

Phenole verbinden sich ebenfalls mit Phosgen zu Chlor-
ameisensaureestern; 2 es giebt aber das gewohnliche Phenol
schon sofort etwas Phenylcarbonat und aus Resorcin lasst
sich auf diese Weise nur Resorcincarbonat darstellen.3 Sehr
auffallend ist es, dass Chlorkohlenoxyd durch auf 200°
erhitztes Phenolnatrium geleitet, auch Salicylsaure liefern

1 Dumas, Ann. chim. et phys. [2], 64, 226 (1833).

2 Kempf, Journ. prakt. Chem. [2], 1, 402 (1870).
8 Birnbaum und Lurie, Berichte, 14, 1754 (1881).

DAS PHOSGEN 193

kann.1 Zur Erklarung der Reaktion muss bemerkt warden,
dass ein Ueberschuss an Natriumhydroxyd nothwendig 1st
und dass allerdings das meiste Phenol unverandert abdestil-
lirt. Da fernerhin auch durch Zusammenschmelzen von
Phenylcarbonat und Phenolnatrium Salicylsaure entstehen
soil, kann man sich die Reaktion in zwei Stadien zerfallend
denken, wovon das erstere die Bildung des Phenylcarbonats
bewirkt. Darauf folgt

(C6H5O)2CO+C6H6ONa+NaOH==

/ONa

C6H4<* +2C6H5OH

xCOONa

Salomon,2 und neuerdings Schone,3 haben gezeigt dass
sich die Merkaptane in ihrem Verhalten gegeniiber Phosgen
und Chlorameisensaureester in keiner Weise von den Alko-
holen unterscheiden. Auch hier ist es bei der Darstellung ge-
mischter Ester gleichgiiltig, ob man das Phosgen direkt auf
das Merkaptan einwirken lasst und Natriumalkoholat zuf ugt,
oder ob man mit Chlorameisensa'ureester auf das Natrium-
merkaptid wirkt.

An Zahl und Interesse die wichtigsten sind die stick-
stoffhaltigen Derivate des Phosgens. Wir haben schon ge-
sehen [17] wie Chlorkohlenoxid mit Ammoniak zusammenge-
bracht Harnstoff liefert; so entsteht auch mit Anilin 4 in
ausserst hef tiger Reaktion das Carbanilid, Diphenylharnstoff ,
und aus jedem primaren Amine der entsprechende, sym-
metrisch zweifach-substituirte Harnstoff.

Aus vielen Beispielen hat Michler 5 dagegen gezeigt, dass

1 Deutsche Patente 29929, 30172, 24151, siehe Berichte, 18, Ref. 12, 40, 90 (1885).

2 Salomon, Journ. pralct. Chem. [2], 6, 433 ff. (1872). 7, 254 (1873).

3 Schone, Journ. pralct. Chem. [2], 30, 416 (1884).

4 Hofmann, Annalen, 67, 267 (1846).

6 Michler et alii, Berichte, 12, 1162, 1166 (1879). 8, 1665 (1875). 9, 396 (1876).
Willm und Girard, Berichte, 9, 449 (1876).

194 MORRIS LOEB

sich sekundare Amine insofern wie Alkohole verhalten, als
sie im Phosgen vorerst nur ein Chloratom ersetzen. So erhalt
er aus Diathylamin (C2H5)2NCOC1 welches er Diathylharn-
stoffchlorid nennt, obwohl die Bezeichnung als Diathyl-
carbaminsaurechlorid verstandlicher ware. Das Chlor kann
durch Erhitzen mit frischen Mengen desselben oder eines
andern Amines ersetzt werden. Auch kommt man mittels
Natriumalkoholate wieder zu Urethanen, in diesem Falle
Estern der zweifach substituirten Carbaminsauren.

Tertiare Basen der rein aliphatischen Reihen scheinen dem
Phosgen keinen Angriffspunkt zu bieten: dagegen tritt bei
den dialkylirten Anilinen die Carbonylgruppe in den Ben-
zolrest ein, und zwar in die Parastellung zur Amidogruppe.
Dimethylanilin 1 wird mit Phosgen schon bei niederer Tem-
peratur zu Dimethylparaamidobenzoylchlorid. Dieses greift
bei hoherer Temperatur wiederum das uberschiissige Di-
methylanilin an, unter Bildung des Hexamethyltriamido-
benzoylbenzols.2

(CH3)2NC6H4CO.C6H3CO.C6H4N(CH3)2

I

N(C6H3)2

Man diirfte erwarten auch das tetraalkylirte Diparaami-
dobenzophenon unter den Reaktionsprodukten zu finden.
Dies ist allerdings dann der Fall, wenn das hierzu berechnete
Mengen verhaltniss eingehalten wird. Im allgemeinen fand
aber Michler dasselbe nicht, an seiner Statt jedoch einen
[18] blauen oder violetten Farbstoff 3 dessen sich seit 1885
dieTechnik bemachtigt hat und von dem Hofmann4 bewiesen
hat, dass er, bei angewandten Dimethylanilin das reine Hexa-
methylpararosanilin reprasentire. Die Reaktion geht im

1 Michler, Berichte, 9, 400 (1876).

2 Michler und Dupertius, Berichte, 9, 1899 (1876).
a Michler, Berichte, 9, 716 (1876).

4 Hofmann, Berichte, 18, 770 (1885).

DAS PHOSGEN 195

Autoklaven vor sich, und Hofmann fand die folgenden
Gleichungen fiir die wahrscheinlichsten.

I. 2C6H5N(CH3)2+COC12 = [(CH3)2NC6H4]2CO+2HC1.
II. [(CH3)2NC6H4]2CO+COC12 =

[(CH3)2NC6H4]2CC12+C02.
III. [(CH3)2NC6H4]2CCl2+C6H5N(CH3)2 =

[(CH3)2NC6H4]3C.HC1+HC1.

In Gegenwart von Aluminiumchlorid lasst sich derselbe
Farbstoff gewinnen, wenn Chlorameisensaureester das Phos-
gen vertritt; 1 oder aber, man kann gleich fertiges Tetra-
methyldiamidobenzophenon mit tertiaren Anilin einschlies-
sen.2 Es braucht in beiden Fallen nur die zweite Gleichung in
der Weise modifizirt werden, dass das Aluminiumchlorid das
Phosgen als Chloriibertrager vertritt. Bemerkenswerth ist
noch der Umstand, dass man auch aus Perchlorameisen-
sauremethylester den Farbstoff gewinnen will:3 es ist dies
eine praktische Erkennung der Thatsache, dass dieser Ester
mit Phosgen polymer und fiir derartige Reaktionen identisch
ist.

Fiir die eigenthiimliche Stellung der Imidgruppe im Pyr-
rol ist charakterisch, dass sich dasselbe dem Phosgen gegen-
iiber fast eben so gut wie ein Kohlenwasserstoff als wie ein
sekundares Amin gebahrt. Ciamician und Magnaghi 4 haben
namlich gefunden, das sich aus dem Pyrrolkalium neben dem
zu erwartenden Harnstoffe (Carbonylpyrrol)

[19] auch das Dipyrrylketon bildet, eine Reaktion die Rath-
selhaftes bietet, aber doch nur in folgender Weise gedeutet
werden kann : —

1 Deutsches Patent 29962, s. Berichte, 18, Ref. 40 (1885).

2 D. R. P. 34463. Berichte, 19, Ref. 226 (1886).

3 D. R. P. 34607. Berichte, 19, Ref. 278 (1886).

4 Ciamician und Magnaghi, Berichte, 18, 414 (1885).

196 MORRIS LOEB

I. 2C4H4NK+COC12= CO' + 2HC1.

/C4H3NK

II. CO + 2HC1 = CO +2KC1

Noch schwieriger mochte die Erklarung zu finden sein,
warum bei den Amidoximen das Phosgen die primare Amin-
gruppe nicht beriihren soil, wahrend es sofort die Nitrol-
gruppe angreif t. So entsteht z. B. nach Falck * beim Benzenyl-
amidoxim

NOH NH2

ii I

nicht OC< sondern OC<

ii I

NOH NH2

Bis jetzt weiss man nur, dass sich diese Anomalie auch
bei andern Reaktionen der Amidoxime wiederfindet. T Jeden-
falls kann es sonst als Regel gelten, dass da, wo die primare
Aminogruppe in complexeren Korpern vorkommt, sie immer
dem Phosgen den gewohnten Angriffspunkt bietet.

Augenscheinlich in der Erwartung, dass die Phosphine
sich dem Phosgen gegemiber ebenso verhalten wiirden wie
die Amine, haben Michaelis und Dittler 2 mil Phenylphos-
phin den Versuch angestellt. Es zeigte sich jedoch, dass
Phosphor fiir das Chlor die starkere Anziehungskraft habe

PH2C6H5+2COC12=PC12C6H5+2CO+2HC1.

1 Falck, Berichte, 18, 2471 (1885).

8 Michaelis und Dittler, Berichte, 12, 339 (1879).

DAS PHOSGEN 197

Da die Carbonylgruppe nur selten mil fiinfwerthigem
Stickstoff verbunden auftritt, steht zu erwarten dass, wenn
[20] uberhaupt das Carbonylchlorid auf den Aminen ent-
sprechende Ammoniumsalze einwirkt, dies nur bei hohen
Temperaturen und unter Dissociation des Salzes geschehen
werde. Dass in der That eine Einwirkung unter solchen
Umstanden stattfinden kann, hat Hentschel in der Verfol-
gung eines gliicklichen Gedankens bewiesen.

Hofmann, der Entdecker des Phenylisocyanats, sogenannten
Carbanils, lehrte dasselbe auf zweierlei Weisen darstellen:
einerseits durch trockene Destination des Carbanilids oder
Oxalyldiphenylguanidins,1 andererseits durch Erhitzen des
Phenylcarbaminsaure-Aethylesters mit Phosphorsaureanhy-
drid.2 Letztere Weise, die allein praktisch ausfiihrbare, war
dennoch muhselig und kostspielig, so dass das Carbanil nur
in kleinen Mengen hergestellt worden war. Hentschel's3
erfolgreicher Gedanke bestand nun darin, dass er Phosgen-
gas Uber geschmolzenes Carbanilid leitete —

/NHC6H5

OCX' +COC12 = 2C6H5NCO + 2HC1.

*NNHC6H5

Da aber das Carbanilid selbst aus Anilin und Phosgen
entsteht, war es nur noch ein Schritt die Darstellung des
Carbanils direkt aus Anilin und Phosgen anzustreben. Um
jedoch zu verhiiten, dass bei der Destination Anilin mit dem
Phenylcyanat ubergehe und dasselbe in der Vorlage in
Carbanilid verwandle, wandte er salzsaures Anilin an, durch
welches er bei 200° Phosgen leitete. Dies Verfahren ist so
vortheilhaft, dass es eine fabrikmassige Darstellung des Car-
banils ermoglicht hat, und auch zur Kenntniss vieler Isocya-

1 Hofmann, Annalen, 73, 9 (1850). 74, 33 (1850).

2 Hofmann, Berichte, 3, 655 (1870).

• Hentschel, Berichte, 17, 1284 (1884).

198 MORRIS LOEB

nate fiihrte, die nun aus den entsprechenden Aminen in einer
Operation erreicht werden konnten. Die Gleichung zeigt,
dass in der That eine Dissociation des Salzes in der Reaktion
begriffen ist.

C6H5NH3C1+COC12 = C6H5NCO+3HC1.

[21] Man wird 'dabei an Bouchardat's Erfahrung erinnert,1
der ja, beim Einleiten von Ammoniakgas in Phosgen, neben
Harnstoff und Guanidin auch Cyanursaure und Melanuren-
saure fand. Die letzteren beiden Substanzen kb'nnen fiiglich
als Derivate der Isocyansaure aufgefasst werden, welche sich
beim ersten Eintreten des Ammoniaks gebildet hatte.

NH3+COC12 = HN = CO+2HC1.

Durch diese Reaktionen werden die Isocyansaure und
ihre "Ester" in die Reihen der Phosgenderivate hineinge-
zogen, zu welchem die so nah verwandten Urethane und
Harnstoff e schon langst gehorten. Es wird daher eine kurze
Uebersicht Uber die theoretischen Beziehungen, in welchen
sich diese Substanzen zu einander und zum Phosgen befinden,
an diesem Orte von Nutzen sein.

Betrachtet man, fiir den Augenblick, das Phosgen als
Chlorid der Chlorameisensaure, so wird der Chlorameisen-
saureathylester natlirlich dasjenige Substitutionsprodukt
sein, in welchem das die Hydroxylgruppe ersetzende Chlor-
atom wiederum durch die Aethoxylgruppe verdrangt ist. Das
Urethan hingegen ist der Ester, der Harnstoff das Amid, der
Amidoameisensaure oder Carbaminsaure. Michler's Harn-
stoff chloride sind hier als die Chloride der zweif ach alkylirten
Carbaminsauren aufzufiihren. Doch giebt es nicht nur
dialkylirte Carbaminsaurechloride : wie Leuckart2 sehr rich-
tig bemerkt, kann man das sogenannte Chlorid der Cyan-

1 Siehe Seite 3 [p. 179 of this vol.]. » Leuckart, Berichte, 18, 874 (1885).

DAS PHOSGEN

199

NH.H

saure nach der Formel | auffassen, und 1st sogar bei

CO.C1
dem von ihm beobachteten Salze des Phenylcyanats nur

NC6H5.H
eine Formel denkbar | . Wir batten in diesen wohl-

CO.C1

defmirten Korpern die Chloride der typischen und der ein-
fach-substituirten Carbaminsaure. Dieselben sind jedoch
nicht sehr bestandig, da sie gerne Salzsaure [22] abspalten
und das innere Anhydrid, das Lactam, der Sauren bilden. Es
waren hiermit die Isocyansaure als Lactam der Carbamin-
saure, das Carbanil als Lactam der Phenylcarbaminsaure
auf zufassen. Harnstoffe und Urethane entstehen daraus
durch Anlagerung von Aminen resp. Alkoholen.

Folgende Tabelle moge veranschaulichen, wie die haupt-
sachlichsten Derivate des Phosgens sich von demselben und
von einander ableiten: —

Aus den primaren
Phosgen-Derivaten

Cl
COOC2H5

NH.H
CO.C1

NC8H5H
COC1

N(CH8)2
COC1

entstehen unter
Einwirkung von
H20

OH

COOC2H6

NH;H:""
colour

NCeH5;S;
CO \OH\

N(CH3)2

CO OH*

nicht bekannt

von C2H5OH

OCA

COOC2H6

NH2
COOO,H,

NC8H5H
COOC2H,

N(CH3)2
CO009H9

von NH,

NH3
COOC2H5

NH3
CO.NH2

NCflH5H
CONHt

N(CH3)2
CONH2

etc. etc.

Lassen sich nun auch die Wurtz'schen, die Friedel und
Crafts'schen Reaktionen des Phenylkerns mit Chlorkohlen-
oxyd auf die primaren Derivate des letzteren ausdehnen?

200 MORRIS LOEB

Fiir die Chlorameisensaureester ist diese Frage schon langst
in ausgiebigster Weise bejaht worden. Leuckart,1 der zuerst
die substituirten Carbaminsaurechloride als solche aussprach,
hat uns auch mit einer derartigen Anwendung derselben
vertrauter gemacht.

[23] Wenn eine Mischung von Phenylcyanat und Benzol
mit Aluminiumchlorid versetzt wird, bildet sich Benzanilid,
und ebenso entsteht aus Phenylcyanat mit den Homologen
des Benzols iminer das Anilid der entsprechenden Saure.
Da die Reaktion nur in Gegenwart von Aluminiumchlorid
stattfinden will, bemerkt Leuckart, dass die einfachste
Erklarung in der Bildung des "salzsauren Carbanils" und
der darauffolgenden Einwirkung dieses Saurechlorids nach
der Friedel und Craf ts'schen Reaktion zu suchen sei : —

Leider fehlen zur Zeit noch Angaben liber das Verhalten
der Michler'schen disubstituirten Carbaminsaurechloride bei
der Aluminiumchlorid-Reaktion ; ein obigem analoges Ver-
halten ware der beste Beweis fur die Richtigkeit der Leuck-
art' schen Annahme.2

SPEZIELLE ANWENDUNGEN

Wenn auch im Vorhergehenden die Aufzahlung der fiir
das Gebahren des Phosgens typischen Reaktionen erschopft
ist, sind noch einige spezielle Anwendungen anzufiihren, der
Resultate wegen, welche dabei erzielt wurden, insbesondere
der Bildung von Korpern die zu den Saurederivaten des
Harnstoffs gerechnet werden.

Die Saureamide zeigen fiir das Phosgen nicht die gleiche

1 Leuckart, loc. cit.

2 Seitdem ich obiges geschrieben, hat sich auch diese Liicke ausgefUllt. Lellmann
und Bonhofer [Berichte, 19, 3231 (1886)] haben das Diphenylcarbaminsaurechlorid
in Gegenwart von Aluminiumchlorid auf Benzol einwirken lassen und Diphenyl-
benzamid erhalten.

DAS PHOSGEN 201

Reaktionsfahigkeit wie die Amine. Wenigstens 1st eine
hohere Temperatur notwendig und entstehen viele Neben-
produkte. Bei primaren Amiden lasst sich allerdings der
Wasserstoff der Amidogruppe noch ersetzen: Schmidt1 hat
durch Erhitzen von Acetamid und von Benzamid mit Phos-
gen Diacetyl- resp. [24] Dibenzoyl-Harnstoff erhalten, ob-
wohl auch hierbei Chlorid und Nitril der Sauren in er-
heblichen Mengen auftraten. Beim Acetanilid, hingegen
scheint die Reaction iiberhaupt noch nicht gelungen zu
sein. Beim Dimethylbenzamid findet der Austausch statt : 2 —

Solche Korper lassen sich aber auf anderen Wegen miihe-
loser herstellen.

Wenn Harnstoff, das Amid der zweibasischen Kohlen-
saure, mit Phosgen erhitzt wird, kann man zweierlei Reak-
tionen erwarten:

/NH H. c /c HI NH . co . NH2

i. oc< ! co n. oc< !

\NH iH Clj X|C1 HI NH . CO . NH2

Nach Schmidt 3 entsteht beim zweitagigen Erhitzen,
unter hohem Druck, auf 100°, nur die letztere Verbindung,
die er Carbonyldiharnstoff nennt. Ebenso entsteht aus
Phosgen und Biuret bei 60° das Carbonyldibiuret. Erhitzt
man letzteres nochmals mit Phosgen so erhalt man fast reine
Cyanursaure, was Schmidt durch folgendes Bild erklart:

XNH— CO— NH— CO— NH iH Clj

'X ..... 7
co— — "•"•" ________ --co

NH— CO— NH— CO— NH |H Clj

1 Schmidt, Journ. prakt. Chem. [2], 6, 35 (1872).

2 Hallmann, Berichte, 9, 846 (1876).

3 Schmidt, Journ. prakt. Chem. [2], 5, 39 (1872).

202 'MORRIS LOEB

Carbonyldiharnstoff liefert mit Phosgen bei 170° nur
theilweise Cyanursaure. Es entsteht ein weisses Neben-
produkt, von derselben Zusammensetzung; ob es mit der
Cyanursaure isomer oder polymer 1st, weiss man noch nicht.
Schmidt nennt es Dicyanursaure.

Es ist zu bemerken, dass diese Synthesen der gewohnlichen
Cyanursaure als gute Argumente ftir die Iso-Konstitution
derselben gelten. Die Diskussion dieser Konstitutionsfrage
[25] gehort nicht hierher: wohl aber will es mir scheinen dass
diesen Synthesen als Beweismittel nicht allzuviel Werth
beizulegen ist. Erstens kann man, so lange ein unbekanntes
Isomer als Nebenprodukt auftritt, nicht entscheiden, ob es
die gewohnliche Cyanursaure ist, welche auf der glattesten
Weise entsteht. Zweitens bedingt die Reaktion, wie oben
angegeben, einen Zerfall eines sehr ausgedehnten Moleklils,
wobei Umlagerungen keineswegs auszuschliessen sind. Zu-
dem sind Reaktionen des Phosgens nicht unbekannt, in denen
eine solche Umlagerung bei gewohnlicher Temperatur frei-
willig eintritt. Ich habe dies selber einmal beim Zusatz von
in Benzol gelostem Phosgen zu o-Amidophenylmerkaptan
schon beobachten konnen. Sofort und quantitativ erfolgte
die Reaktion —

xNH2 /N\

C6H4< +COC12=C6H4< *)C(OH)+2HC1.
'XSH 'NSX

Es war also in der Kalte dieselbe Wanderung eines Wasser-
stoff atoms vom Stickstoff zum Sauerstoff erfolgt, die man
zur Erklarung einer Synthese der normalen Cyanursaure
mittels Phosgen annehmen miisste.

Oxamid mit Phosgen erhitzt, gab nach Schmidt nur
Carbonyldiharnstoff, unter gleichzeitiger Entwickelung von
viel Kohlenoxid —

DAS PHOSGEN 203

Basarow 1 hingegen will auf diese Art Parabansaure er-
halten haben —

CO-NH2 CO-NHx

| +COC12= | >CO+2HC1.

CO-NH2 CO-NHX

Wahrend Phosgen auf Harnstoff erst bei betrachtlicher
Warme einwirkt, geschieht dies nach Will 2 bei den Thio-
harnstoffen sofort, obwohl mit anderen Resultaten. Es
deuten [26] dieselben sogar auf eine abweichende Konstitu-
tion der geschwefelten Harnstoff e von den sauerstoffhaltigen.
Verschiedene Umstande uberzeugten Will, dass die Reaktion
beim Sulf ocarbanilid den Verlauf —

c< =s

\

I >CO
HC1|X

nicht haben kann, sondern, dass das Endprodukt derart ist,
dass man als einfache Erklarung folgende Gleichung anneh-
men mochte —

C^NC6H5H+COC12=C— NC6H6+2 HC1

\SH \ \

Sulfocarbanilid V- CO

Als vornehmster Grund diente das Verhalten der Sub-
stanz beim Erhitzen

C< +COS

•*NC6H6
S— CO

1 Basarow, Berichte, 6, 477 (1872).

2 W. Will, Berichte, 14, 1486 (1881).

204 MORRIS LOEB

Ware die Formel symmetrisch, so miissten als Spaltungs-
produkte erwartet werden

=s>CO = C6H5NCS+C6H5NCO

Man wird sich erinnern, dass auch andere Forscher zur
Annahme derselben Formel fiir die Thioharnstoffe geleitet
worden sind, wie Will.1 Die Untersuchungen des Letzteren
erstreckten sich nur auf die substituirten Korper dieser Gruppe.
Indem ich versuchte, zur Vervollstandigung auch das
einfache [27] Thiocarbamid zu ahnlicher Reaction zu bringen,
fand ich, dass es selbst bei den hochsten Temperaturen die es
ertragt, vom Phosgen nicht beeinflusst wird.

Es existiren noch eine Anzahl amidahnliche Substanzen,
in denen der Sauerstoff des Saureradikals durch eine Imid-
gruppe ersetzt ist, die Amidine und Guanidine. Von diesen
war bisher nur das Triphenylguanidin auf sein Verhalten mit
Chlorkohlenoxyd gepriift worden.2 Auf Veranlassung des
Herrn Professors A. W. Hofmann habe ich mich bemiiht,
auch aus Amidinen Phosgenderivate darzustellen, und werde
ich im "Experimentellen Theil" iiber diese und andere da von
herriihrende Versuche weitlaufiger reden. Meinen Bericht
iiber die Phosgenderivate wiirde ich jedoch, bei der grossen
Anzahl derselben die im vorausgehenden keine Ermahnung
finden konnten, nicht fiir vollstandig erachten, ohne ein Ver-
zeichniss der mir bekannten einschlagigen Litteratur.

1 So Liebermann, Berichte, 12, 1588 (1879).
* Michler und Keller, Berichte, 14, 2181 (1881).

DAS PHOSGEN 205

[28] LITTERATUR-VERZEICHNISS
DARSTELLUNG DBS PHOSGENS

Aus Kohlenoxyd und Chlor. Davy, Phil. Trans. Royal Society, 1812, 144.

Willm und Wischin, Zeitschr.f. Chem. 1868, 5.

Paternd, Gaaa. Chim. Ital. 8, 233 (1878).

Goebel, Berzelius Jahresberickt, 16, 162.

Hofmann, Annalen, 70, 139 (1849).
Aus Schwefelkohlenstoff und Unterchlorigsaureanhydrid. Schiitzenber-

ger, Berichte, 2, 219 (1869).
Aus Schwefelkohlenstoff, Chlor und Schwefelsaure.

Berzelius, Lehrbuch der Chemie, Bd. 2.

Kolbe, Annalen, 54, 148 (1845).

Aus Tetrachlorkohlenstoff. Schiitzenberger, Comptes Rendus, 66, 747;
(1868). 69, 352 (1869).

Armstrong, Berichte, 3, 730 (1870).

Gustavson, Zeitschr.f. Chem., 1871, 615.
Aus Chloroform. Dewar und Cranston, Chem. News, 20, 174 (1869).

Emmerling und Lengyel, Berichte, 2, 547 (1869).
Aus Perchlorameisensauremethylester. Cahours, Ann. chim. et phys. [3],

19, 352 (1847).
Aus Trichloressigsaurem Natrium.

Kolbe, Annalen, 64, 150 (1845).

Henry, Berichte, 12, 1845 (1879).

ElGENSCHAFTEN

Berthelot, Compt. Rend. 87, 571 (1878).
Thomsen, Berichte, 16, 2619 (1883).
Berthelot, Annalen, 166, 228 (1870).

[29] REAKTIONEN MIT KOHLENWASSERSTOFFEN
Darstellung von Sdurechloriden und Ketonen

Mit Kohlenwasserstoffen der Fettreihen.

Harnitz-Harnitzky, Compt. Rend. 60, 923 (1865).

Berthelot, Bull. Soc. Chim. n. s. 13, 9 (1870).

De Clermont et Fontaine, ibid. seq.
Mit Zinkmethyl. Butlerow, Berichte, 3, 426 (1870). Siehe auch Butlerow,

Organische Chemie, S. 297.
Mit Benzol. Harnitz-Harnitzky, Compt. Rend. 68, 748 (1864).

Berthelot, Bull. Soc. Chim. n. s. 13, 9 (1870).

Friedel, Crafts und Ador, Berichte, 10, 1854 (1877).
Mit Toluol. Ador und Crafts, Berichte, 10, 2173 (1877).
Xylol. Ador und Rilliet, Berichte, 11, 399 (1878).

Elbs und Olberg, Berichte, 19, 408 (188C).

206 MORRIS LOEB

Mit Anthracen. Graebe und Liebermann, Berichte, 2, 678 (1869).

Behla. Berichte, 18, 3169 (1885).
Mit Phenanthren. Ibid.

Brombenzol. Wurtz, C. R. 68, 1298 (1869).

Thiophen. Gattermann, Berichte, 18, 3013 (1885).

Pyrrol. Ciamician und Magnaghi, Berichte, 18, 414 (1885).

REAKTIONEN MIT AI^KOHOLEN UND PHENOLEN
Darstettung von Chlorameisensaure- und Kohlensaure-Estern

Mit Methylalkohol. Dumas und Peligot, Ann. chim. et phys. 68, 52 (1835).

Hentschel, Berichte, 18, 1177 (1885).
Mit Aethylalkohol. Dumas, Ann. chim. et phys. 64, 226 (1833).

Propylalkohol. Roemer, Berichte, 6, 1101 (1873).

Isopropylalkohol. E. Mylius, Berichte, 6, 972 (1872).

Isoamylalkohol. Medlock, Quart. Journ. Ckem. Society, 1, 368 (1849).

Glycol. Nemirowsky, Journ. prakt. Chem. 28, 439 (1843).

Glycolchlorhydrin. Nemirowsky, Journ. prakt. Chem. 31, 173 (1844).

Glycolsaureester. Heintz, Annalen, 154, 257 (1870).

Milchsaure. Kempf, Journ. prakt. Chem. [2], 1, 412 ff. (1870).

Epichlorhydrin. Kempf, ibid.

Phenol. Kempf, Patent des Deutschen Reiches, 30172. Berichte, 18, Ref .

40. 17 (1885).
Mit Kresol. Kempf.

Thymol. Kempf.

Nitrophenol. Kempf.
[30]
Mit Eugenol. Salicylaldehyd. Lowenberg, Inaug.-Diss. Berlin, 1885.

Resorcin. Birnbaum und Lurie, Berichte, 14, 1754 (1881).

Merkaptanen. Salomon, Journ. prakt. Chem. [2], 6, 433 8. (1872).

7, 254 (1873).

Schone, Journ. prakt. Chem. [2], 30, 416 (1884).
Mit Thiophenol. Lowenberg.

Naphtol, a, p. Lowenberg.

REAKTIONEN MIT ALDEHTDEN UND SAUREN
Chlorirung derselben

Mit Acetaldehyd. Harnitz-Harnitzky, Annalen, 111, 192 (1859).

Friedel, Compt. Rend. 60, 930 (1865) und Ann. chim. et phys. [4],

16, 403 (1869).

Kraut, Annalen, 147, 107 (1868).
Stacewitz, Zeitschr. f. Chem. 1869, 321.
Kekule und Zincke, Annalen 162, 125 (1872).
Eckenroth, Berichte, 18, 518 (1885).

DAS PHOSGEN 207

Mit Benzaldehyd. Kempf.

Aceton. Wroblewski, Zeitschr.f. Chem. [2], 4, 565.
Essigsaure. Kempf.
V. Meyer, Annalen, 156, 271 (1871).

REAKTIONEN MIT PRIMAREN AMINEN
Darstellung symmetrischer Harnstoffe

Mit Ammoniak. J. Davy, Phil. Trans. 1812. 144.

Regnault, Ann. chim. et phys. 69, 180 (1809).

Natanson, Annalen, 98, 287 (1856).

Bouchardat, Compt. Rend. 69, 94 (1869).

Fenton, Journ. Chem. Soc. 35, 793 (1879).
Mit Anilin. Hofmann, Berichte, 57, 267 (1846).
Orthotoluidin. Girard, Berichte, 6, 444 (1873).
Amidopropylbenzol. Francksen, Berichte, 17, 1224 (1884).
Amidoisobutylbenzol. Pahl, Berichte, 17, 1240 (1884).
Benzidin. Michler und Zimmermann, Berichte, 14, 2174 ff. (1881).
m-Phenylendiamin. Michler und Zimmermann.
p-Amidodimethylanilin. Michler und Zimmermann.
Anisidin. Miihlhauser, Berichte, 13, 922 (1880).
Amidoazobenzol. Berju, Berichte, 17, 1400 (1884).

[31] REAKTIONEN MIT SEKUNDAREN AMINEN
Darstellung von Carbaminsa'urechloriden und Harnstqffen

Mit Dimethylanin. Michler und Escherich, Berichte, 12, 1162 (1879).
Diathylamin. Michler, Berichte, 8, 1665 (1875).
Methylamilin. Michler und Zimmermann, Berichte, 12, 1165 (1879).
Aethylendiphenyldiamin. Michler und Keller, Berichte, 14, 2181 (1881).
Diazoamidbenzol ) « » • », , n»»o /-.oo-f\

Diazobenzolparatoluid \ Sarauw' Benchte' U> **** (1881)'
Diphenylamin. Michler, Berichte, 9, 396 (1876).
Willm und Girard, Berichte, 9, 449 (1876).

REAKTIONEN MIT TERTIAREN AMINEN
Bildung amidirter Saurechloride und Benzophenone

Mit Dimethylanilin. Michler, Berichte, 9, 4500, 716 (1876).

Michler und Dupertius, Berichte, 9, 1899 (1876).

.Patente, Berichte, 17 (1884). Ref. 40,339, 60. 18(1885). Ref.7.

Hofmann, Berichte, 18, 770 (1885).
Mit Diathylanilin. Michler, Berichte, 8, 1665 (1875).

Michler und Gradmann, Berichte, 9, 1912 (1876).

208 MORRIS LOEB

REAKTIONEN MIT AMMONIUMSALZEN
Bildung von Isocyanaten

Mit salzs. Anilin. Hentschel, Berichte, 18, 1178 (1885).

Methylamin. Gattermann und Schmidt, Berichte, 20, 118 (1887).

Aethylamin. Dieselben.

m-Phenylendiamin. Gattermann und Wrampelmeyer, Berichte, 18,

2604 (1885).
Mit Benzidin. Snape, Journ. Chem. Soc. 49, 255 (1886).

m-Toluylendiamin. Snape.

Phenylhydrazin. Snape.

REAKTIONEN MIT AMIDEN
Bildung von Ureiden

Mit Acetamid. Schmidt, Journ. prakt. Chem. [2], 6, 39 ff. (1872).

Oxamid. Schmidt.

Basarow, Berichte, 5, 477 (1872).
Mit Benzamid. Schmidt.
[32J
Mit Dimethylbenzamid. Hallmann, Berichte, 9, 846 (1876).

Harnstoff. Schmidt.

Biuret. Schmidt.

Diphenylharnstoff. Hentschel, Berichte, 18, 1284 (1885).

Diphenylthioharnstoff. Will, Berichte, 14, 1486 (1881).

Ditolythioharnstoff. Will.

REAKTIONEN MIT ANDEREN KORPERN

Mit Benzenylamidoxim. Falck, Berichte, 18, 2471 (1885).

Aethenyldiphenylamidoxim. Gross, ibid. 2483.

Acetessigester. Conrad und Guthzeit, Berichte, 19, 19 (1886).

Buchka, Ber. 18, 2090 (1885).
Mit Propionitril. Hencke, Annalen, 106, 285 (1858).

Phenylphosphin. Michaelis und Dittler, Berichte, 12, 339 (1879).

Silicomethan. Wilm und Winschin, Annalen, 147, 150 (1868).

[33] EXPERIMENTELLER THEIL

DIE Versuche von Michler und Keller 1 iiber die Ein-
wirkung des Phosgens auf das symmetrische Triphenylguani-
din haben zu keinem erheblichen Resultate gefiihrt, da die
entstehenden Substanzen die Kriterien der Reinheit nicht
besassen. Man muss sogar bezweifeln, dass der von ihnen
erhaltenen bei 134° schmelzenden Substanz wirklich die
Formel

/NC6H5N
C<=NC6H5 >CO

zukomme, da dieselbe von Stojentin 2 fiir seinen wohldefin-
irten, bei 190° schmelzenden Korper in Anspruch genommen
wird, welchen er aus dem Guanidin mittels des Aethoxalyl-
chlorids erhalten hat.

Der Versuch sollte nun zeigen, ob ein Amidin, vermoge
seiner einfacheren Bauart, sich der Reaktion williger herge-
ben wollte. Naturgemass fiel meine Aufmerksamkeit zuerst
dem Aethenyldiphenyldiamin

zu, welches durch die Eigenschaften der leichten Darstellung
und ziemlichen Bestandigkeit vor den meisten Korpern dieser
Klasse hervorstach.

Im'Laufe dieser Arbeit habe ich die verschiedenen Dar-
stellungsweisen, die man flir das Aethenyldiphenyldiamin
vorgeschlagen hat, priifen konnen, und bin zu der Ueberzeu-

1 Berichte, 14, 2181 (1881). a Journ. prakt. Chem. 32, 29 (1844).

210 MORRIS LOEB

gung [34] gelangt, dass diejenige, welche A. W. Hof mann1 bei
der ersten Beschreibung dieser Substanz empfohlen hat, am
raschesten und sichersten zum Ziele fuhrt, wenn auch die
Reaktion einen ziemlichen Aufwand an Ausgangsmaterial
erfordert

14C6H5NH2+3CH3COOH+2PC13=

+6C6H5NH2HCH-

2C6H5NH2H3PO3

Ich verfuhr gewohnlich so, dass ich 35 Gramm Anilin
und 13 Gramm Eisessig in einem Kolben vermischte und zu
der erkalteten Losung nach und nach 25 Gramm Phosphor-
trichlorid gab. Die Anfangs heftige Reaktion wurde durch
Abkiihlen gedampft. Alsdann wurde der Kolben, mit einem
Riickflussktihler versehen, in einem Oelbade erwarmt, dessen
Temperatur langsam auf 165° erhoht wurde. Hier verblieb
derselbe, bis das Aufhoren der Salzsaureentwickelung das
Ende der Reaktion anzeigte. Die Schmelze loste sich fast
vollkommen in kochendem Wasser; beim Erkalten krystalli-
sirten oft geringe Mengen Acetanilid aus. Das aus der fil-
trirten Losung mittelst Ammoniak gef allte Amidin brauchte
zur Reinigung nur noch einmal aus Alkohol umkrystallisirt
zu werden. Die Ausbeute betrug die Halfte des Gewichts
des angewandten Anilins und war folglich nach obiger
Gleichung fast theoretisch.

ElNWIRKUNG DES PHOSGENS IM UEBERSCHUSS AUF

AETHENYLDIPHENYLDIAMIN

Zehn Gramm der wohlgetrockneten und feingepulverten
Base wurden mit einem Ueberschuss verflussigten oder auch
in Benzol gelosten Phosgens in einem Glasrohre eingeschlossen
und 4-5 Stundenlang im Wasserbade erwarmt; die Tempera-

1 A. W. Hofmann, Monataberichte der Berliner Akod. 1865, 249.

PHOSGEN— EXPERIMENTELLER THEIL 211

tur durfte 60° nicht ubersteigen. Der Rohreninhalt hatte
hierauf eine tiefgelbe Farbe angenommen und bestand zu
zwei Dritteln aus salzsaurem Amidin; mit warmem Benzol
oder Aether Hess [35] sich eine Substanz ausziehen, welche
beim Verdunsten des Losungsmittels gewohnlich als ein kle-
briges, gelbes Harz zuriick blieb. Auf Zusatz einiger Tropfen
kalten, absoluten Alkohols verwandelte sie sich jedoch in einen
Krystallbrei, aus welchem das Oel durch Abpressen entfernt
wurde. Nunmehr wurden die Krystalle, unter sorgfaltiger
Vermeidung des Siedens, aus verdtinntem Alkohol umkry-
stallisirt, bis sie den gelben Stich verloren und bei 110° kon-
stant schmolzen. Die Substanz bildete alsdann kleine farb-
lose Nadeln und erwies sich als chlorhaltig. Zur Analyse
wurde sie noch mit Aether gewaschen und bei 110° getrock-
net.

I. 0.3013 Gramm Substanz gaben 0.6335 Gramm CO2

und 0.0979 Gramm H2O;
II. 0.2746 Gramm Substanz gaben 20.75 ccm N, t =

24.25°, B0=755 mm, 7 = 16.6 mm;
III. 0.3107 Gramm Substanz gaben 0.2705 Gramm AgCl

nach Carius.1
Diese Analysen wiesen unzweideutig auf eine Formel

Verlangt ftir: Gefunden:

CieHi2N2Cl2O2 I II III

C 192 57.31 57.34

H 12 3.58 3.61

N 28 8.36 8.46

Cl 71 21.19 21.54

O 32 9.56

335 10.000

1 Die Chlorsilber-NiederschlSge wurden auf einem tarirten Gooch'schen Platin-
trichter gesammelt, bei 120° getrocknet, und gewogen.

MORRIS LOEB

Es hatte also f olgende Reaktion stattgef unden : -

Aus 10 Gramm Amidin liessen sich 3 Gramm des neuen
Korpers, also 60 Procent der theoretischen Menge gewinnen.
Der gute Ausfall des Verf ahrens hangt aber wesentlich davon
ab, dass der Korper in Losungsmitteln keiner hohen Tem-
peratur [36] ausgesetzt werde, da seine Bestandigkeit nur
sehr gering ist. Seine Zersetzbarkeit trat auch storend zu
Tage, als ich seine Konstitution durch Darstellung von Deri-
vaten erforschen wollte.

Von kochendem Wasser wird er nicht angegriffen, von
Sauren und Alkalien hingegen in das Amidin zuriickver-
wandelt. Beim Kochen mit Alkohol treten sofort Essigester
und Chlorathyl auf; beim Erkalten scheiden sich kleine
Nadeln in Menge aus, welche chlorfrei sind, bei 234° schmel-
zen und sich hierdurch, sowie durch den beim Erhitzen
auftretenden Carbanilgeruch, als Carbanilid charakterisiren.
Die Zersetzung hat hier den Amidinrest selber ergriffen : —

Ci6Hi2N2Cl2O2+3C2H5OH =

CO(NHC6H5)2+CH3COOC2H5+2C2H5C1+C02

Es wurden Versuche gemacht, die Chloratome durch
Aminogruppen zu ersetzen. Da sich weder wasseriges noch
alkoholisches Ammoniak bewahrten, wurde der Korper in
Benzol gelost und trockenes Ammoniakgas hindurchgeleitet.
Es schied sich unter Erwarmung eine der Chlormenge genau
entsprechende Quantitat reinen Salmiaks aus. Die Losung
enthielt aber bloss Aethenyldiphenyldiamin, was sich nur
durch die f olgende Gleichung erklaren lasst: —

Analog entstehen mit heissem Anilin das Amidin, salz-
saures Anilin und Carbanilid.

PHOSGEN — EXPERIMENTELLER THEIL 213

Fur sich liber ihren Schmelzpunkt erhitzt, zersetzt sich
die Substanz bei 150° unter reichlicher Entwickelung von
Phosgengas und von Phenylisocyanat.

Diese Thatsache 1st eine wesentliche Stiitze zur Annahme
einer Konstitution welche sonst noch durch das von Michler
entdeckte Verhalten der sekundaren und tertiaren Aniline
gegen Phosgen geboten erscheint

N-COC1

[37] Erfreulicherweise habe ich diese Annahme auch ferner
bestatigen konnen, durch Darstellung eines

Esters. Es muss hierbei naturlich jede Erwarmung ver-
mieden werden. Eine 2 Atomen entsprechende Menge Na-
trium wurde in Aethylalkohol gelost und nach dem Erkalten
die alkoholisehe Losung des Chlorids [1 Molekiil] allmahlig
unter Abklihlung hinzugesetzt. Von dem sich sofort ab-
scheidendem Kochsalz abfiltrirt und iiber Schwefelsaure im
luftleeren Raume verdunstet, hinterliess die Pliissigkeit eine
chlorfreie Substanz, welche nach zweimaligem Umkrystalli-
siren aus Aether harte, glanzende, rhombische Krystalle
bildet, die bei 90.5° schmelzen. Der Analyse der in vacua
getrockneten Substanz zufolge, ist in der That der Ester
entstanden.

C6H5

/NCOOC2H5
CH3C<

:^NC6H4COOC2H5

I. 0.2965 gr Substanz gaben 0.7363 gr CO2 und 0.1730 gr
H20.

214 MORRIS LOEB

II. 0.1775 gr Substanz gaben 12.7 ccm N. t = 10,°

B0 = 755.8 mm, T = 7.1 mm.

III. 0.2020 gr Substanz gaben 14.4 ccm N. t = 12.5,°
B0= 772.8 mm, r = 8.4 mm.

Verlangt fur: Gefunden:

C2oH22N2O4 I II III

C 240 67.79 67.74

H 22 6.21 6.48

N 28 7.91 8.51 8.60

O J54 18.08

354 99.99

Selbst in der Kalte ist der Ester in alkoholischer Losung
unbestandig. Von wasserigem Ammoniak wird er, ebenso
wie das Chlorid, in das Amidin zuruckverwandelt. Da ich
nun auf diesem Wege keine Amidoverbindungen zu [38]
gewinnen vermochte, bemtihte ich mich eine directe Anlager-
ung von Cyansaure resp. Rhodanwasserstoffsaure an das
Amidin, welche zu dem gesuchten ahnlichen Korpern ge-
f iihrt hatte, zu bewerkstelligen. Auch diese Versuche schlugen
fehl, da das Cyanat des Amidins schon in kalter, wassriger
Losung Kohlensaure und Ammoniak abspaltet; das Rhod-
anat, welches ein Harz darstellt, ist zwar bestandiger, lagert
sich jedoch nicht in den Thioharnstoff um, sondern verwan-
delt sich oberhalb 100° in ein Ubelriechendes Oel.

Uebrigens lasst sich auch der Ester nicht direct aus dem
Amidin, durch die sie sonst so bequeme Anwendung des
Chlorameisensaureesters, gewinnen. Eine Einwirkung des-
selben findet erst bei 60° statt; nach Verdunsten der vom
salzsauren Amidin befreiten Fliissigkeit verbleibt eine halb-
feste Masse, welche an Aether kleine Mengen eines nicht
krystallisirenden Oeles abgiebt und im Uebrigen aus Carb-
anilid besteht.

PHOSGEN— EXPERIMENTELLER THEIL 215

EINWIRKUNG VON PHOSGEN AUF UBERSCHUSSIGES
AETHENYLDIPHENYLDIAMIN

Aethenylimidobenzanilid

Wenn man, statt auf oben angegebener Weise zu verf ahren,
Phosgengas in eine siedende Chloroformlosung des Amidins
einleitet, so andert sich auch das Resultat. Es entsteht eine
chlorfreie Verbindung, welche ihre Existenz dem Zusammen-
treten von einem Molekiil Phosgen und einem Molektil
Amidin verdankt.

Dieselbe entsteht daher auch, und zwar in glatterer
Reaktion, wenn Phosgen in Benzol gelost bei 80° auf einen
Ueberschuss von Aethenyldiphenyldiamin einwirkt. Nach
einstiindiger Erhitzung wird das Einschlussrohr geoffnet, die
Fliissigkeit vom salzsauren Amidin befreit und das Benzol
verdunstet. Der krystallinische Riickstand wird mit kalter,
starkverdiinnter Salzsaure von unveranderter Base befreit
und [39] umkrystallisirt. Er ist in Aether, Alkohol, Chloro-
form und Benzol loslich und krystallisirt besonders aus letzt-
genanntem Losungsmittel in grossen, glanzenden Tafeln
vom Schmelzpunkt 118°. Er ist viel bestandiger als das
chlorhaltige Derivat.

Die Analyse der bei 100° getrockneten Substanz ergab
Zahlen aus welchen die Formel Ci5Hi2N2O berechnet wurde.

I. 0.1874 gr Substanz gaben 0.5314 gr CO2 und

0.0948 gr H2O.
II. 0.2031 gr Substanz gaben 0.5706 gr CO2 und

0.1024 gr H2O.

III. 0.1720 gr Substanz gaben 17.9 ccm N, t=23.3°,
Bo =758 mm, r = 16.7 mm.

£16 MORRIS LOEB

IV. 0.2263 gr Substanz gaben 24 ccm N, t =21°, B0 =757 mm,
r = 14.5 mm.

Verlangt fiir: Gefunden:

C15H12N20 I II III IV

77.33 76.61
5.62 5.60

11.73 12.07

Es lasst diese Zusammensetzung nur eine Auffassung zu

/NC6H5
CH3C<'

Dieser Korper, den ich Aethenylimidobenzanilid benennen
will, diirfte auch bei der schon erwahnten Phosgenabspaltung
entstehen, welche das Chlorid beim Erhitzen erleidet

/NC6H4CO Cl
CH3C<

\N - |CO Cl

C6H5

Die stets zugleich auftretende Carbanilentwickelung ver-
eitelt jedoch seine Isolirung. Wird das reine Aethenylimido-
benzanilid [40] Uber seinen Schmelzpunkt erhitzt, so braunt
es sich bald, und entwickelt etwas Isonitril. Mit verdiinnter
Salzsaure gekocht spaltet es sich vollkommen, wobei Anilin
und Phenylcyanat als Produkte auftreten.

Diese Reaktionen des Phosgens sind die ersten die mit
einer Substanz ausgefiihrt worden sind, welche je einen sekun-
daren und einen tertiaren Anilinrest enthalt. Sie zeigen die

PHOSGEN— EXPERIMENTELLER THEIL 217

Gleichwerthigkeit der beiden Michler'schen Reaktionen an,
insofern als bei einer niedrigen Temperatur der Eintritt der
Carbonylgruppe in den Phenylkern ebenso rasch erfolgt wie
in den Imidorest.

Andernf alls musste auch ein Korper —

COC1

aufgetreten sein, der sich jedoch nicht beobachten liess.

Ich wollte nunmehr diese Reaktion auch auf andere
Amidine von analoger Constitution ausdehnen, und stellte
zu diesem Zwecke das Benzenyldiphenyldiamin dar. Wieder-
um bewahrte sich Hofmann's Darstellungsweise am besten,
mit der Modification, das man fertiges Benzanilid und Anilin
derEinwirkung des Phosphortrichlorids aussetzt; dieSchmelze
konnte nur mit kochender concentrirter Salzsaure ausgezogen
werden. Die Einwirkung des Chlorkohlenoxyds auf dieses
Amidin liess sich aber nicht verfolgen, da die Reaktions-
produkte allzu geringe Krystallisationsfahigkeit zeigten.

Das Methenyldiphenyldiamin, welches ebenfalls von
Hofmann dargestellt worden ist, ist wenig bestandig. Es
erschien daher angemessen, das Propionamidin, behufs Prii-
fung dieser Reaktion, darzustellen : da dieser Korper noch
nicht bekannt ist, habe ich ihn und, zur Vervollstandigung
der Reihe, auch die homologen Butenyl- und Isobutenyl-
Amidine analysiert und ihre Eigenschaften beobachtet.

[41] PROPENYLDIPHENYLDIAMIN

Zur Darstellung wird genau wie beim Aethenylderivat
verfahren und zwar werden wiederum 3 Theile Anilin, 1

218 MORRIS LOEB

Theil Propionsaure und 3 Theile Phosphortrichlorid ange-
wandt. Die salzsaure Losung lasst auf Alkalizusatz die Base
als belles Oel fallen, welches nur langsam fest wird. Dieselbe
1st in Alkohol und Aether noch loslicher als das Aethenyl-
amidin, und krystallisirt in langen weissen Nadeln, die bei
105° schmelzen.

Behufs Gewinnung des Platindoppelsalzes wurde die Base
in starkverdiinnter Salzsaure aufgelost und mit Platinchlorid-
losung versetzt. Der alsbald erfolgende gelbe Niederschlag
ist in Wasser und Weingeist wenig, in absolutem Alkohol
gar nicht, in starker Salzsaure dagegen sehr leicht loslich.

Er wurde aus salzsaurehaltigem Alkohol umkrystallisirt,
mit absolutem Alkohol gewaschen und bei 100° getrocknet.
Das Salz wurde so in prachtvollen, scharlachrothen Prismen
von einiger Grosse erhalten.

0.6119 Gramm Substanz, im Tiegel verbrannt, hinterliessen
0.1395 Gramm Asche.

Verlangt fur: Gef linden:

(Ci5Hi6N2)2.2HClPtCl4

Pt 22.64 22.79 Procent

BUTENYLDIPHENYLDIAMIN

Dasselbe entstand aus 1 Theil Buttersaure, 5 Theilen
Anilin und 3 Theilen PCls. Die Ausbeute war, auf die Saure
berechnet, theoretisch. Schmelzpunkt der in Nadeln krystal-
lisirenden Base 106.5°.

Das Platindoppelsalz fallt auf Zusatz von Platinchlorid
zur salzsauren Losung nach einiger Zeit nieder, und hat als-
dann eine schwachgelbe Farbe. Es ist in Alkohol und heissem
Wasser leicht loslich. Aus ersterem krystallisirt es in gelb-
rothen, aus letzterem in braunrothen Nadeln, welche [42]
bei durchscheinendem Lichte fast farblos erscheinen. Es
wurde bei 100° getrocknet und analysirt.

PHOSGEN— EXPERIMENTELLER THEIL 219

0.5869 Gramm Substanz, im Tiegel verbrannt, hinter-
liessen 0.1298 Gramm Asche.

Verlangt fiir: Gef undent

C32H38N4PtCl6

Pt 21.92 22.12 Procent

ISOBUTENYLDIPHENYLDIAMIN

Die auf ebendieselbe Weise dargestellte Base fallt als
Oel aus, welches nur nach langerem Kochen mit Wasser fest
wird. Sie 1st in heissem und kaltem Wasser unloslich und
lasst sich mit Dampf destilliren. Die Krystalle schmelzen
bei 79°. Von kalter konzentrirter oder heisser verdiinnter
Salzsaure wird dieses Amidin leicht zersetzt, unter Bildung
des Isobutenylanilids.

Platindoppelsalz. Dasselbe wird aus einer massig ver-
diinnten Losung als gelbes Krystallpulver erhalten. Es ist
in heissem und kaltem Wasser und in heissem Alkohol loslich.

0.5052 gr bei 100° getrockneter Substanz hinterliessen
0.1109 gr Pt.

Verlangt fiir: Gef linden:

Pt 21.92 21.95 Procent

Die Einwirkung des Phosgens auf das Propenyldiphenyl-
diamin habe ich zwar versucht und einen krystallisirbaren
Korper erhalten. Derselbe ist jedoch nur in kleinen Quanti-
taten erhaltlich und sehr zersetzlich. Er wurde aus Aether
umkrystallisirt, war jedoch nicht frei von Chlor zu erhalten,
obwohl eine Chlorbestimmung zeigte dass dasselbe nur Ver-
unreinigung sei. Eine bei 76° schmelzende Portion wurde
analysirt, ohne jedoch Zahlen zu geben aus welchen sich etwas
deuten liesse.

Indem nun die Einwirkung des Phosgens auf Amidine,

220 MORRIS LOEB

welche sich von Aethenyldiphenylamidin durch die zu ihrer
[43] Bildung angewandten Sauren unterscheiden, keine
greifbare Resultate geliefert hatte, war es mogiich dass sich
em besserer Erfolg bei einem Aethenylarnidin erzielen Hesse,
in welchem an Stelle des Anilins eine homologe Base getreten
ist. Ich beschloss daher, Versuche mit Derivaten des Para-
resp. Orthotoluidins anzustellen.

EINWIRKUNG DES PHOSGENS AUF AETHENYLDI-P-TOLUYL-

DIAMIN

Dieses Amidin ist zuerst von Hofmann dargestellt, jedoch
von Bernthsen * genauer beschrieben worden. Ich befolgte
die Vorschrift des Ersteren, und erhielt so leicht ein Produkt
dessen Schmelzpunkt 188° mit Bernthsen's Angabe im Ein-
klang stand. Je 10 g des trocknen Amidins wurden mit 2.8 g
Carbonylchlorid in Benzollosung 3-4 Stunden lang im Ein-
schlussrohr auf 60° erhitzt. Es hatten sich salzsaures Amidin
und eine im Benzol losliche Substanz gebildet, welche nach
freiwilligen Verdampfen des Losungsmittels als gelbes Oel
zuriickblieb. Zum krystallisiren war dieselbe nur dadurch
zu bringen, dass man sie mit einigen Tropfen eiskaltes ab-
soluten Alkohols Ubergoss, worauf sie zu einem Krystall-
brei erstarrte. Sofort zwischen Filtrirpapier abgepresst und
mit warmem absoluten Aether behandelt, erwiesen sich
jedoch die Krystalle zum grossen Theil als in Aether unlos-
liches, bei 254° schmelzendes Carbotoluid, wahrend ein kleiner
Theil in Losung ging. Durch Vereinigung der Produkte
mehrerer Operationen, und sorgfaltiges Umkrystallisiren
aus Aether, gelang es mir, eine kleine Menge einer konstant
bei 108° schmelzenden Substanz zu isoliren, welche chlor-
haltig war und in gut ausgebildeten kurzen Prismen kry-
stallisirte. Die Ausbeute war jedoch so schlecht, dass es

1 Hofmann, Annalen, 184, 364 (1877).

PHOSGEN— EXPERIMENTELLER THEIL 221

mir nur mb'glich war, eine einzige Chlorbestimmung auszu-
f iihren, deren Resultat allerdings gut auf einen Korper —

.;NC7H6COC1

CH3Cf stimmt.

XNHC7H6COC1

[44] 0.2756 gr Substanz gaben nach der Carius'schen
Methode 0.2241 gr AgCl.

Verlangt fiir: Ci8H16N2Cl2O2 Gefunden:

Cl 19.56 20.11 Procent

Die Absicht, auch mil dem Orthoditoluylamidin Versuche
anzustellen, musste ich aufgeben, da ich nicht erwarten
durfte eine krystallisirbare Substanz aus diesem Ausgangs-
produkte zu erhalten, welches selber einen sehr niedrigen
Schmelzpunkt besitzt. Da dieses Amidin jedoch bisher noch
nicht beschrieben worden ist, gebe ich an dieser Stelle
meine Beobachtungen wieder.

AETHENYLDI-OTOLUYLDIAMIN

Zur Darstellung verwandelte ich 40 gr Orthotoluidin, 12
gr Eisessig und 25 gr Phosphortrichlorid. Nachdem die
Schmelze mit kochendem Wasser ausgezogen war, fiel aus der
Losung, auf Alkalizusatz, ein nichtkrystallisirendes, farb-
loses Oel aus. Wasserdampf trieb unverandertes Toluidin
aus demselben aus; der Ruckstand erstarrte jedoch erst nach
einigen Tagen, und zwar ohne Spuren einer krystallinischen
Struktur. Aus Alkohol und sonstigen Losungsmitteln seined
sich immer ein Oel aus, das alsdann amorph erstarrte. Auch
salpetersaure, schwefelsaure, essigsaure und oxalsaure Salze
liessen sich auf keine Weise krystallinisch erhalten. Dagegen
entstanden schone Nadeln des salzsauren Salzes beim Ein-
leiten von Chlorwasserstoffgas in eine trockene atherische
Losung der Base.

222 MORRIS LOEB

Zur Charakterisirung der Substanz stellte ich das Platin-
doppelsalz dar. Es ist dasselbe ein gelbes, in Wasser schwer-
losliches, Krystallpulver, welches sich beim Erhitzen mit
Wasser oder Alkohol leicht zersetzt. Ueber Schwefelsaure
und dann bei 100° getrocknet und im Porzellantiegel ver-
brannt, lieferte es die der Theorie entsprechende Menge
Platin. 0.5818 gr Substanz hinterliessen 0.1273 gr Asche.

Verlangt fur: C32H38N4PtCl6 Gefunden:

Pt 21.92 21.88 Procent

[45] Den Schmelzpunkt der Base fand ich bei 45-47°.

Ehe ich das Feld der Amidine verliess, lag der Wunsch
nahe, den Versuch anzustellen, ob nicht noch eine andere
Reaktion, die der Cyananlagerung, sich bei denselben anwen-
den liesse. Hofmann hatte dieselbe zuerst beim Anilin beob-
achtet und dann auch auf Guanidine ausgedehnt.1 In der
That ist sie auch auf das Aethenyldiphenyldiamin anwendbar.

EINWIRKUNG DES CYANS AUF DAS AETHENYLAMIDIN

Eine gesattigte atherische Losung des Amidins, mit 2-3
Tropfen Wassers versetzt, farbt sich beim Durchleiten von
Cyangas allmahlig dunkel. Unterbricht man das Einleiten
sob aid die Fliissigkeit weinroth geworden, und lasst sie unge-
fahr 16 Stunden verschlossen stehen, so ist sie noch bedeutend
nachgedunkelt und der Geruch des Cyans demjenigen der
Blausaure gewichen. Zuweilen haben setzen sich auch
schwarze Krusten an den Wanden des Gef asses ab. Von diesen
wird abfiltrirt, der Aether bei moglichst niedriger Tempera-
tur verdunstet und der klebrige, braune Riickstand mit
kaltem, verdiinnten Alkohol vom farbenden Harze befreit.
Das verbleibende, weisse, krystallinische Pulver, welches
zwischen Filtrirpapier moglichst abgepresst und iiber

1 Hofmann, Annalen, 66, 129 (1848).

PHOSGEN— EXPERIMENTELLER THEIL 223

Schwefelsaure getrocknet wird, lost sich sehr schwer in kaltem
Aether und Benzol. Es lasst sich nicht umkrystallisiren, da
es beim Erhitzen in Losungsmitteln rasch verharzt; mit
Alkohol benetzt, zersetzt es sich sogar schon an der Luft.
In reinem Zustande schmilzt es unter Zersetzung^bei 165°,
wird jedoch schon gegen 120° violett und dann braun. Aus
5 gr des Amidins lassen sich 3 gr des Produktes erhalten.

Aus der Elementaranalyse ergiebt sich fiir den Korper
eine Zusammensetzung Ci6Hi6N4O.

I. 0.2169 gr Substanz gaben 0.5409 gr CO2 und
0.1023 gr H2O.

II. 0.2625 gr Substanz gaben 0.6596 gr CO2 und

0.1380 gr H2O. [46]

III. 0.2060 gr Substanz gaben 0.5184 gr CO2 und

0.1152 gr H2O.

IV. 0.3659 gr Substanz gaben 63.75 ccm N, t=25°,

B0 =760.5 mm, r = 18.4 mm.
V. 0.1498 gr Substanz gaben 27.2 ccm N, t=24°,
B0 =765.5 mm, r = 17.34.

Berechnet fflr: Gefunden:

Ci6H16N40 I II III IV V Mittel

C 192 68.57 68.00 68.52 68.60 — 68.37

H 16 5.71 5.24 5.84 6.21 5.76

N 56 20.00 — 19.55 20.32 19.94

O 16 5.71 — , 5.93

280 99.99

Da der Sauerstoffgehalt wahrscheinlich, analog mehreren
ahnlichen Cyanderivaten, vom Kry stall wasser herriihrt, lasst
sich diese Bruttoformel auflosen: —

C16H16N40=Ci4H14N2.C2N2+H20.

Es hat somit die Reaktion nicht den Verlauf genommen
welchen Hof mann beobachtet hat, die Anlagerung eines Cyan-

224 MORRIS LOEB

molekiils an je zwei primare oder sekundare Amingruppen.
Viel eher f olgt das Amidin hierin der Amidobenzoesaure, dass
sich ein ganzes Cyanmolekiil an eine einzelne ersetzbaren
Wasserstoff enthaltende Stickstoffgruppe anlagert. Da nach
Griess * aus der Amidobenzoesaure die Cyancarbimidoamido-
benzoesaure entsteht —

C6H4COOH
NH-C=NH

CN
so liesse sich der neue Korper nach demselben Schema —

CH3C-NC6H5+H2O
C=NH

CN

[47] schreiben und kann ich diese als die wahrscheinlichste
Konstitutionsformel aufstellen.

Der Korper erleidet beim Erhitzen mit Wasser unter
Druck eine Umwandlung in einen rothen Farbstoff, welcher
in Chloroform loslich, aber nicht krystallisirbar ist und daher
nicht weiter untersucht wurde. Zugleich tritt ein starker
Isonitrilgeruch auf.

Mineralsauren zersetzen die Substanz vollkommen, so dass
Anilin und Essigsaure die hauptsachlichsten Produkte sind.
Wenn man dagegen das Ci6Hi6N4O in ganz kleinen Portionen
in siedende starke Kalilauge eintragt, so lost es sich darin
auf, unter Abscheidung von viel Anilin. Nachdem letzteres
durch andauerndes Kochen entfernt ist, setzen sich beim

1 Griess, Berichte, 11, 1985 (1878).

PHOSGEN— EXPERIMENTELLER THEIL 225

Erkalten flimmernde Krystallblattchen ab. Die abfiltrirte
Fliissigkeit enthalt Essigsaure, Kohlensaure, Oxalsaure und
Blausaure; die ausgeschiedenen Krystalle sind in Benzol und
Aether nicht, in heissem Alkohol nur sehr sparsam loslich,
leicht dagegen in heisser und verdiinnter Salzsaure. Auf
Alkalizusatz fallt ein flockiger weisser Niederschlag aus, der
zur Reinigung einmal aus Alkohol umkrystallisirt wird.
Weisse, silberglanzende Blattchen, die bei 214° schmelzen
und sich beim vorsichtigen Erhitzen zwischen Uhrglasern
zum Theil sublimiren lassen. Dies Alles gab dem Zersetzungs-
produkt den Anschein als ware es das Hofmann'sche Cyan-
anilin 1

C6H6NH— C=NH

C6H5NH— C=NH

und eine Analyse hat die Vermuthung in der That besta'-
tigt: 0.2076 gr der getrockneten Substanz gaben 42 ccm N,
t=17.5°, B0=764.7, r = 11.6.

Verlangt fiir: Gefunden:

Ci4H14N4

N 23.53 23.63 Procent.

[48] 5 Gramm Ci6Hi6N4O haben 1.5 Gramm Cyananilin
gelief ert, welches Gewicht der Half te der in ersterem enthalt-
enen Anilinreste entspricht. Es kann also nicht bezweifelt
werden dass der Einfluss der Kalilauge f olgender war —

2Ci6H16N4O+2H2O =

Wenn diese glatte Spaltung auch nicht als strenger Beweis
fiir die oben aufgestellte Konstitution des Korpers Ci6HieN4O
gelten kann, so betrachte ich sie dennoch als wesentliche

1 Hofmann, Annalen, 66, 129 (1848).

226 MORRIS LOEB

Sttitze derselben, da sie aus derselben ungezwungen hervor-
geht.

CCH3

//

;

0#I#NC6H5

I \ /

INH=C — C=NH|

) I 1

CN - CN

Andere Umwandlungen mit dem Korper Ci6Hi6N4O aus-
zufiihren 1st mir nicht gelungen.

Ich habe nun noch einige andere Substanzen der Ein-
wirkung des Phosgengases unterworfen und glaube, dass es
einigen Werth hat iiber diese Versuche zu berichten, wenn
dieselben auch nicht zur Auffindung noch unbekannter Deri-
vate gefiihrt haben.

EINWIRKUNG DES PHOSGENS AUF URETHAN

In der Hoffnung zu einem Carbonyldiurethan
CO(NHCOOC2H5)2

zu gelangen, habe ich wiederholt 7 Teile Aethylurethans
mit 1 Theil Phosgen, entweder verfliissigt oder in Benzol
gelost, im Rohr auf 75° erhitzt. Beim Oeffnen der Rohren
entwichen jedesmal unter starkem Drucke Salzsaure und
Chlorathyl, und es verblieb als Reaktionsprodukt eine [49]
chlorfreie, in kaltem Wasser unlosliche Substanz. Dieselbe
musste wiederholt aus Alkohol oder Chloroform umkrystalli-
sirt werden, bis sie bei 194° einen konstanten Schmelzpunkt
erreichte. Sie wurde bei 120° getrocknet und analysirt,
wobei es sich herausstellte, dass die Formel nicht die erwar-
tete sondern C4HsN2O3 sei.

PHOSGEN— EXPERIMENTELLER THEIL 227

I. 0.2749 gr Substanz gaben 0.3703 gr CO2

und 0.1549 gr H2O.

II. 0.2986 gr Substanz gaben 55 ccm N, t=24°,

B0 =759.4 mm, r = 17.34 mm.
III. 0.2105 gr Substanz gaben 38 ccm N, t = 19°,
B0 =764.45 mm, r= 12.72 mm.

Berechnet filr:

Gefunden

C4H8N203

I

II

c

48

36.36

36.12

H

8

6.06

6.12

N

28

21.21

20.73

0

48

36.36

III

20.94

132 99.99

Es hatte sich somit Allophansaureester gebildet, der sich
auch noch dadurch nachweisen Hess, dass er sich durch Er-
hitzen mit Ammoniaklosung in das Biuret verwandelte. Ob
sich nun dieser Ester direkt gebildet hat, nach der Gleichung

4NH2COOC2H5+COC12 =

2NH2CO-NH-COOC2H5+2C2H6C1+CO2+H2O

oder ob das zuerst entstandene Carbonyldiurethan beim Um-
krystallisiren zerfallt, vermag ich nicht zu entscheiden. Ich
neige jedoch zu ersterer Ansicht.

Versuche mit dem homologen Alanin fiihrten zu keinem
Resultat.

Ferner ergab sich aus wiederholten Versuchen die Un-
fahigkeit des Phosgen sich mit Carbazol, Succinimid oder
Phthalimid, oder deren Kaliumderivaten zu verbinden.

Auf Hydrazobenzol wirkt Phosgen wie eine Saure: das-
selbe verwandelt sich in Benzidin, welch* letzteres, wie schon
[50] bekannt, erst bei hohen Temperaturen von Chlorkohlen-
oxyd angegriffen wird.

MORRIS LOEB

Auch mit Thioharnstoff wollte das Phosgen nicht in
Wechselwirkung treten, obwohl die Versuche bei verschiede-
nen Temperaturen angestellt wurden. Selbst nach wochen-
langem Zusammenstehen liess sich keine Veranderung er-
kennen.

Orthoamidophenylmerkaptan, welches ich der Giite des
Herrn Professor Hofmann verdankte, reagirt sehr leicht
mit Phosgen. Es wurde mit Benzol vermischt und tropfen-
weise mit Phosgenlosung versetzt, bis kein salzsaures Salz
mehr ausfiel. Hierbei wurde viel Hitze frei. Das Benzol
enthielt einen chlorfreien, sofort bei 136° konstant schmelzen-
den Korper, welcher unschwer als Hofmanns Oxymethenyl-
verbindung zu erkennen war.

CeH/' X)C(OH)

Schon Gronvik1 hatte aus dem Orthoamidophenol mittels
Chlorameisensaureesters den analogen Korper erhalten

C6H4<;/ X)C(OH)

Versuche, das Phosgen auch auf das Benzenylamidomer-
kaptan einwirken zu lassen, blieben erfolglos.

[51] Die im vorstehenden beschriebenen Versuche habe ich
im Juli 1885 im I. Chemischen Laboratorium der Universi-
tat Berlin begonnen und im Januar 1887 beschlossen. Es ist
mir eine grosse Freude an dieser Stelle bezeugen zu konnen
wie viel ich meinen verehrten Lehrer, Herrn Geheimrath
Professor Hofmann, fiir seine lebhafte Anregung, Belehrung
und UnterstUtzung schulde und mit welcher Dankbarkeit

1 Bull. Soc. Chim. n. s. 25, 177 (1876).

PHOSGEN-EXPERIMENTELLERJTHEIL 229

ich mich immer des Wohlwollens erinnern werde, das er mir
stets gezeigt.

Auch Herrn Professor Gabriel sage ich fiir viele freund-
liche Rathschlage meinen herzlichsten Dank.

OPPONENTEN:1

Die Herren: W. Bowman, Cand. phil.
K. Auwers, Dr. phil.
A. Reissert, Dr. phil.

THESEN.

I.

Die vier Bindungseinheiten des Kohlenstoffs sind unter einander
gleichwerthig.

n.

Die einfach-substituirten Thioharnstoffe sind Derivate des Thiohara-
stoffes.

III.

Die Clausius'sche Theorie ist die beste Erklarung der elektrolytische
Vorgange.

1 In the public examination for the Doctor's degree, Morris Loeb defended
the accompanying theses against the three opponents here named. [EDITOR.]

THE MOLECULAR WEIGHT OF IODINE IN ITS
SOLUTIONS x

IT is a matter of everyday observation that iodine has the
property of dissolving with different colors in different liquids;
in some it shows the reddish-brown hues of its solid and
liquid states; in others it acquires the violet color so charac-
teristic of its vapor. The inference seems very natural that
this diversity of color must depend on a different form of
aggregation of the iodine atoms within the solvent. Since
the molecules of solids and liquids appear to be more com-
plex than those of gases, we might suppose that the red solu-
tions contain more complex molecules of iodine than do the
violet ones. This is, in fact, the usual assumption; but apart
from certain qualitative indications, there has been no proof
of its truth; quantitative evidence has not yet been forthcom-
ing in support of the hypothesis. That I have been fortunate
in obtaining such, I owe to those new [806] means of investi-
gating the state of dissolved matter with which the happy
generalizations of Raoult, and the skillful mathematical de-
ductions of van't Hoff, have furnished us. I refer to the
phenomena of "osmotic pressure," which can be measured
by the depression of freezing-point and vapor tension which
liquids experience when mingled with a foreign substance.
By the advice of Professor Ostwald, I undertook to attack
the problem of the molecular weight of iodine in its solutions
by the vapor-tension method, and I now give the results of
the experiments carried out under his direction at the Chem-
ico-Physical Laboratory of Leipzig University.

1 Reprinted from the Journal of the Chemical Society, 63, 805 (October, 1888).

MOLECULAR WEIGHT OF IODINE 231

Two liquids at once presented themselves as the appropriate
solvents, ether and carbon bisulphide; they both have a con-
siderable vapor tension, and they may be considered as typi-
cal of the two kinds of solvents for iodine. For, whereas
many iodine solutions show impure tints, that in ether is of a
deep reddish-brown, and that in carbon bisulphide of a pure
violet. It was not so easy to find a proper
apparatus, as Raoult's is quite inap-
plicable. He operates in the Torricellian
vacuum, and has merely to note the com-
parative heights of the mercury when
the solution and the pure solvent are
introduced above it. In the case of
iodine, all contact with mercury must
obviously be avoided. After various
attempts, the following apparatus was
devised, which is an adaptation of
Regnault's manometer to the [807] pres-
ent purpose. It consists of two bottles of
nearly equal capacity, provided with care-
fully ground, hollow glass stoppers. To
these stoppers, glass tubes are adapted,
60 cm. long, and of about 6 mm. bore, which are bent twice
at right angles, so that there is an ascending limb and a hori-
zontal piece of 10 cm. length each, and a descending limb, 40
cm. long, for each half of the apparatus. The lower ends of
these two tubes are connected with each other by means of
a T-tube, to which they are joined by short pieces of very
stout rubber tubing; the third end of the T-tube serves as a
communication with the exterior when needed, and carries a
rubber tube with pinchcock. The communication between
the two halves of the apparatus can also be interrupted by
means of a pinch-cock on one of the rubber joints. In one

MORRIS LOEB

of the bottles, the iodine solution is placed, whilst the pure
solvent is put into the other. These liquids are contained in
glass tubes, drawn out at both ends into capillaries that make an
obtuse angle with the wider part. The tubes are first weighed,
then filled, closed before the blowpipe, and again weighed.
They contain about 3 cc. of liquid, pass readily through the
narrow necks of the bottles, and can be broken by moderately
shaking the bottles. Before this is done, however, the bottles
are closed with their stoppers — smeared with deliquesced
phosphoric acid to insure a perfect joint — and are placed in a
water-bath of constant temperature. The T-tube is now con-
nected with a two-necked Woulff's bottle, filled with colored
distilled water, and communicating by its second neck with an
air-pump. Air is exhausted, until the pressure within the appa-
ratus is diminished to an extent equivalent to the amount of
tension to be expected from the vapors of the liquids, and
the pinch-cock is then closed, so as to interrupt communica-
tion with the Woulff s bottle. The air-pump being discon-
nected, atmospheric pressure is restored in the WoulfFs
bottle, and on carefully opening the pinch-cock the water is
allowed to ascend halfway up the long tubes; the pinch-cock
is then closed, and the WoulfFs bottle removed. The appa-
ratus is thus converted into a very delicate differential mano-
meter, affording direct readings of the difference of pressure
in the two bottles in terms of water centimetres; for con-
venience, the two tubes are brought closely together (see
figure) and a scale is placed behind them.

The apparatus is quite independent of changes in the at-
mospheric pressure; the change in capacity, caused on either
side by an alteration in the level of the water in the tubes, is,
moreover, so slight in proportion to the volume of air in the
bottles, that it can safely be neglected; the effect of capillarity
in the two tubes is equal and opposite, so that this too may

MOLECULAR WEIGHT OF IODINE 233

be left out of account. There remains only the effect of the
air left in the apparatus by the air-pump. It [808] is obvious
that equilibrium being once established, and the tempera-
ture in all parts remaining the same, the pressure of the air
in the one half will always counterbalance that in the other.
In fact, partial exhaustion was only resorted to as a means of
preventing too great an outward pressure during the course
of the experiment, since it was difficult to prevent leakage
where there was any outward pressure upon the stoppers.
Partial exhaustion, besides obviating this difficulty, proved
directly advantageous by promoting a more rapid diffusion
of the vapors, and thereby shortening the duration of the
observations.

The apparatus having been made ready, communication
between the two halves was temporarily interrupted, and the
tubes containing the liquids broken by shaking the two
bottles simultaneously. After ten to fifteen minutes communi-
cation was restored, and now the level of the water in the two
manometer tubes, equal before, was seen to differ consider-
ably, indicating a higher pressure in the bottle containing the
pure solvent. Readings being made from time to time, this
difference of level sometimes appeared virtually constant for
hours, whilst in other cases it would exhibit considerable
variations, which I ascribe to slight inequalities of tempera-
ture and to the unequal concentration of the solution in dif-
ferent parts of its bottle. After standing twenty-four hours,
the aqueous vapor from the manometer tubes generally began
to diffuse into the bottles, and by moistening the ether or
carbon bisulphide rendered further observations useless.

The readings give the difference between the vapor tension
of the pure solvent and that of the solution; that is, the de-
pression of tension which corresponds with the proportion
of iodine to solvent in the solution. To calculate the con-

234 MORRIS LOEB

centration of the solution at the moment of observation, I re-
quired two data: the amount of iodine and of solvent intro-
duced into the bottle (which I obtained from the weighings
of the sealed tubes and from the known strength of the solu-
tion with which they were filled) ; and secondly, the amount
of solvent which had assumed the gaseous state, and must
therefore be deducted from the original quantity in solution.
This was easily calculated by the regular gasometric formula,
the volume of gas being 270 cc., the temperature being known,
and the pressure being that of the vapor of the pure solvent,
less the depression formed by the direct observation. I found
that I could employ the vapor tensions of pure ether and car-
bon bisulphide from tables calculated from Regnault's meas-
urements, as a few direct comparisons proved that they agreed
with those given by my apparatus, within the limits of ex-
perimental error. The expression for the amount of solvent
remaining in the solution at the moment of observation is
therefore —

[809] g70.M(/-g)

760(l+aO

where a = grams of solvent originally present ;/= the tension
at the temperature t of the pure solvent, expressed in milli-
metres of mercury; 0=the depression of tension, also in terms
of millimetres of mercury; w= weight in grams of 1 cc. of the
vapor under standard conditions. Now if b = the weight of io-
dine in the solution, and p - the ratio of solvent to iodine —

b

I. p-

270 . w . (f-e)
760 . (1+ctf)

The concentration being thus ascertained, the calculation
of the molecular weight of iodine was made according to the
formula —

MOLECULAR WEIGHT OF IODINE 235

n.

MI and Mo being the molecular weights of iodine and solvent
respectively. This is a working formula derived by Raoult
from an expression for the relation between the ratio of mole-
cules of solvent and substance dissolved on the one hand, and
the ratio between the tension of the pure solvent and the
depressed tension on the other, where the dissolved substance
itself has a comparatively insignificant tension. It is interest-
ing to note that the latter expression was reached independ-
ently and almost simultaneously by Planck.1

In the following tabulated statement of my observations,
the first two columns show the weights of the ingredients
of the solution originally introduced; the third gives the tem-
perature; the fourth, the depression of tension; the fifth, the
true tension of the solution; the sixth, the concentration as
calculated by formula I; finally, we have the molecular weight
as calculated by formula II. Before giving the results ob-
tained for iodine, I think it useful to give a summary of a
few test experiments made on the molecular weight of naph-
thalene, which not only proved the trustworthiness of the
method, but also showed that there is no specific difference
between ether and carbon bisulphide which could invalidate
the effect of the great difference of the molecular weights
found for iodine.

1 Compare Raoult, Zeilschr. physik. Chem. 2, 372 (1889), and Planck, ibid. 2,

408 (1888). , [EDITOR.]

236 MORRIS LOEB

[810] NAPHTHALENE IN CARBON BISULPHIDE

a

b

t

e

f-6

P

M1

Average

5-4082

0 2586

27-5°
27-5

9-47
10-93

377-09
375-65

5-18
5-18

129
135

|l32

NAPHTHALENE IN ETHYL ETHER

a

b

t

e

f-e

P

Mt

Average

2-8359

0-1462

27-5°

21-12

557-27

6-53

127

1

I

I

27-5
27 5

21-08
21-14

557-31
557-25

6-53
6-53

128
127

I 127-5

—

—

27 5

21-17

557-22

6 53

128

J

Average in CS2 MI = 132

Average in C4Hi0O MI = 127-5

Theory for Ci0H8 MI = 128.

IODINE IN CARBON BISULPHIDE

a

b

t

e

f-e

P

M,

Average

5-6528

0-4388

27-3°

9-72

373-92

8-37

239

1

—

—

27 3

8-59

375-05

8-37

278

I 0«,

—

—

27 3

8-81

374-83

8-37

271

f 264

-

—

27 3

9-08

374 56

8-37

268

J

5-1862

0-4026

27-5

8-10

378-48

8-46

300-5

}

—

27-5

8-10

378-48

8'46

300-5

J- 300'5

5-4579

0 2594

27-5

4-60

381-98

5-15

324

1

27-5

4-51

382-07

5-15

332

_

_

27-5

4-66

381-92

5-15

320

[ 320

—

—

27-5

4-76

381-82

5-15

314

f

—

—

27-55

4-80

382-52

5-15

310

J

4-9030

0-2330

27-5

4-67

381-91

5-20

326

1 39ft • f\

—

—

27-5

4-60

381-98

5-20

327

s Oiov O

Total average MI = 303-25 ± 5-10

Theory for I2 MI = 254

Theory for I3 MI = 381.

MOLECULAR WEIGHT OF IODINE 237

[811] IODINE IN ETHYL ETHER

a

b

t

e

f~e

P

M,

Average.

3-2578

0 2546

27-2°

8-20

563-69

9-59

488

—

27-2

7-50

564-39

9-59

534

—

_

27-2

7-81

564-08

9-59

512

504-7

_

—

27-35

8-09

567-05

9-60

497

—

—

27 3

8-16

565-90

9-60

492-5

3-2864

0-2058

27 3

7-46

566-60

7-68

443

1

—

—

27 3
27 3

4-84
5-04

569-22
569-02

7-68
7-68

653
642

I 577-2

—

—

27 3

5-66

568-40

7-68

571

J

3-6809

0-2305

27-4

6-51

569-72

7-50

486-5

1

27-4
27-45

6-48
6 77

569-75
570-54

7-50
7-51

487
468-5

I 480-7

3 4343

0-3151

27-5

6 99

571-40

7-62

461

]

I

I

27 5
27 5

7-14
6 43

571-25
571-96

7 62

7-62

451
501-5

I 466-1

—

—

27-5

7-14

571 25

7-62

451

J

Total average MI = 507*2 ± 10'5

Theory for I4 MI = 508.

It seems very probable, therefore, that iodine in its red so-
lutions has a molecular weight corresponding to 1^ whilst in
the violet solution in carbon bisulphide there is a less complex
aggregation, giving a value between 12 and Is. I may as well
remark that the values for p in the ether solutions correspond
approximately with the ratio of one iodine molecule in 100
molecules of the solutions; in the carbon bisulphide solutions,
this ratio varies between 1 : 100 and 1 : 200. Whilst greater
dilution might appear more advisable from a theoretical point
of view, it offers an apparently insurmountable difficulty in
practice. A glance at the formulae used in the calculation
shows that the value of e enters three times in such a manner
that any error attached to it would be tripled. As e decreases
with the concentration, it is evident that a greater dilution
than that employed by me will soon bring e to a point where

238 MORRIS LOEB

the chance errors of observation become proportionately very
great. Hence I agree with Raoult when he says that the
method of determining molecular weights by the depression
of the freezing-point is preferable to the method by vapor
tensions. But for the problem which immediately interested
me I lacked a liquid which would solidify, and also dissolve
iodine with a pure violet color, benzene, for instance, giving
a very [812] impure bluish-brown. Nevertheless I endea-
vored to obtain what corroborative evidence I could by experi-
menting on the freezing points of iodine in acetic acid and in
benzene, but was forced to give up the attempt by the very
slight solubility of iodine in these menstrua at low tempera-
tures; the molecular weight of iodine as calculated from vari-
ous series of observations seemed to increase continuously
with the concentration, so that there was no point in the nar-
row limits between extreme dilution and saturation at which
the molecular weight would appear constant, and could be
accepted as trustworthy. A paper published since then by
Paterno and Nasini1 on this subject contains a few figures
for the molecular weight of iodine in acetic acid and benzene
solutions, but I am unable to draw any other inference from
them than from my own.

1 Berichte, 21, 2155 (1888).

[606] UEBER DEN MOLEKULARZUSTAND DES
GELOESTEN JOBS1

DAS Jod lost sich bekanntlich in Schwefelkohlenstoff und
Kohlenwasserstoffen mil violetter Farbe, in Alkohol, Aether
und andern Alkoholderivaten dagegen rotbraun auf, einer-
seits seiner Dampfform, andererseits seinem festen Zustande
entsprechend. Man folgert gewohnlich daraus, dass das Jod
diese Zustande in den Losungen behielte, oder, genauer ge-
sprochen, dass die rote Farbe komplexere Molekel 2 andeute
als die violette. Eine quantitative Stiitze dieser Annahme
hat sich meines Wissens bisher nicht erforschen lassen;
qualitativ allerdings sprechen Analogieen in den Absorptions-
spektren dafiir, sowie eine Beobachtung E. Wiedemanns,3
wonach eine Losung von Jod in Schwefelkohlenstoff bei
starker Abkiihlung aus violett in rotbraun ubergeht. In der
That wird die erste versprechende Aussicht auf Beantwortung
derartiger Fragen liber die Elemente durch jene Beziehungen
eroffnet, welche neuerdings Raoult zwischen den Molekular-
zustanden einerseits und Aenderungen in der Dampftension
und dem Gefrierpunkte des Losungsmittels andererseits her-
vorgehoben, und van 't Hoff mathematisch hergeleitet hat.
Auf Veranlassung Herrn Professor Ostwalds habe ich nun
Versuche angestellt, um zu erfahren, ob sich wirklich eine
Verschiedenheit des Molekulargewichts des Jods in seinen
Losungen aus den Dampfdruckserniedrigungen derselben
ergiebt: ich glaube dies jetzt entschieden bejahen zu konnen.

Die Wahl des Losungsmittels war nicht schwer, da Aether

1 Reprinted from Zeitschrift fur physikalische Chemie, 2, 606 (1888).

2 This now almost obsolete spelling was generally used in 1888. [EDITOR.]
8 Phys.-Med. Gesell. Erlangen (1887).

240 MORRIS LOEB

und Schwefelkohlenstoff, welch e beide sehr hohe Dampf-
spanmmg besitzen, den Farbenunterschied in besonders
schoner Weise zeigen und daher fur typisch gel ten konnen,
wahrend viele andere Losungsmittel, wie Benzol, die unrei-
nen Nuancen eines Uebergangszustandeshervorbringen. Da-
gegen liess sich die Raoultsche Methode, die Losungen in
die Barometerleere einzufiihren und den Quecksilberstand
direkt zu messen, deshalb nicht anwenden, weil [607] eine Be-
riihrung zwischen Jod und Quecksilber nicht statthaft war.
Es hat sich indeiSsen eine Modification eines Regnaultschen
Apparates als niitzlich erwiesen, welche eine bequemere
Handhabung und raschere Ausfiihrung gestattet, genaue
Messinstrumente unnotig macht und, trotz einiger neuen
Fehlerquellen, hinreichende Genauigkeit besitzt, Fragen wie
die vorliegende zu entscheiden.

Zwei Reagensflaschen von annahernd gleichem Gehalt
erhalten guteingeschliffene, hohle Glasstopsel, welche beider-
seits offen sich nach oben in Glasrohren aus starkem Glase,
von etwa 6 mm. lichter Weite, fortsetzen. Diese Rohren wer-
den zweimal rechtwinklig gebogen, so dass der unten offene
Schenkel 50 cm. lang ist, wahrend der andere Schenkel und
der wagrechte Teil nur je etwa 105 cm. lang sind. Diese
beiden Rohren werden untereinander durch Stiicke dicken
Gummischlauchs, deren eines einen Quetschhahn fiihrt,
unter Vermittelung eines T-Rohres verbunden. Das dritte
Ende dieses T-Rohres, — zweckmassig nach oben gekehrt,
statt wie der Uebersichtlichkeit halber gezeichnet, — dient
zur Verbindung nach aussen und ist deshalb mit Schlauch
und Quetschhahn versehen. Es werden nun die Flaschen mit
den die Flussigkeiten enthaltenden Rohrchen beschickt,
welche aus oben und unten stumpfwinklig ausgezogenen
diinnwandigen Glasrohren gefertigt sind, 2 bis 3 cc. fassen
und nach dem Fiillen vor der Stichflamme geschlossen wer-

DAS GELOESTE JOD

241

den. In die eine Flasche kommt die Losung, in die andere

das reine Losungsmittel : die Flaschen werden geschlossen,

nachdem noch zu besserer Dichtung die

Stopsel mit syrupsdicker Phosphorsaure-

losung bestrichen worden. Das offene

Ende der T-Rohre wird mit einem Rohre

verbunden, das auf den Boden einer

WoulfTschen Flasche reicht, welche mit

gef arbtem Wasser gefiillt ist und mittels

ihrer anderen Miindung mit einer Luft-

pumpe kommuniziert. Die Luft im Ap-

parate wird so lange verdiinnt, bis der

Unterdruck den zu erwartenden hb'ch-

sten Druck um weniges ubertrifft, der

Quetschhahn alsdann geschlossen und

die WoulfTsche Flasche mit der Aussen-

luft in Verbindung gesetzt. Durch vor-

sichtiges Oeffnen des Hahnes lasst man

nun so viel Wasser in die Rohren treten, dass dasselbe die Half te

der langen Schenkel erfiillt. Man entfernt die Woulffsche

Flasche und hat nun ein empfindliches [608] Differentialmano-

meter, welches Druckunterschiede in Wasserhohe direkt an-

giebt, vom ausseren Druck ganz unabhangig ist und wegen der

verschwindenden Verschiebung der Volume in beiden Halften

(die grosste beobachtete Differenz bedingte kaum einen hal-

ben cc., wahrend die Flaschen 270 cc. fassen) hierfiir eine Kor-

rektion unnotig machte. Der Kapillaritatseinfluss hebt sich

gegenseitig auf und die im Apparate verbleibende Luft ubt auf

beiden Seiten gleichen Druck aus, so dass ein Verdiinnen der-

selben bloss zum Vermeiden eines grossen Druckunterschiedes

zwischen dem Innern des Apparates und der Atmosphare,

wodurch bei langerem Stehen ein Austreiben der Stopsel

und folgliche Undichtigkeit haufig vorkam, notig war. Es

242 MORRIS LOEB

ergab sich aber auch der weitere Vorteil, dass eine schnelle
Verbreitung des Dampfes ermoglicht ward, wodurch die
Dauer der Versuche eine kiirzere wurde. Der Versuch wurde
folgendermassen fortgefiihrt: die Flaschen wurden dicht zu-
sammen in einen Wasserthermostaten bis an den oberen
Rand des Halses gesteckt, wahrend die beiden Manometer-
rohren ausserhalb desselben ebenfalls dicht beisammen her-
abhingen. Nachdem an einer lotrecht daneben hangenden
Skala mit Millimeterteilung die kleine Niveaudifferenz fest-
gestellt, wurde die Verbindung der beiden Halften mittels
des hierzu angebrachten Quetschhahns aufgehoben und die
Rohrchen durch Schiitteln der Flaschen geoffnet. Es dauerte
eine Viertelstunde ehe man die Verbindung wieder herstel-
len durfte, ohne ein Ueberspritzen der Sperrfliissigkeit in die
eine oder die andere Flasche befiirchten zu miissen; dann
aber stellte sich rasch ein Gleichgewichtszustand her, der
manchmal viele Stunden lang unverandert blieb, manchmal
aber um Centimeter Wasserdruck schwankte. Die Ursache
des Schwankens lag wohl in ungleichmassiger Verteilung
der Losung in der Flasche und an kleinen Temperatur-
schwankungen, welche die Witterung der letzten Wochen
sehr begtinstigte. Nach eintagigem Stehen war kein Ver-
trauen mehr in die Werte zu setzen, da alsdann die Diffu-
sion des Wasserdampfes bis zur Flasche vorgeschritten war,
die Fliissigkeiten nicht mehr trocken waren.

Die nun mit Riicksicht auf die urspriingliche Differenz
korrigierten Unterschiede des Wasserstandes ergaben also
den Unterschied zwischen der Spannung des reinen Losungs-
mittels und der jeweiligen Losung; d. i. die Erniedrigung,
welche die gerade in der Losung bestehende Konzentration
des Jods bewirkte. Zur Berechnung dieser Konzentration
brauchte ich zweierlei Daten: die Mengen des thatsachlich
vorhandenen Jods und Losungsmittels, und die Menge des

DAS GELOESTE JOD 243

letzteren, welches in Gasform der Losung sich entzogen hatte.
Die Rohrchen enthielten deshalb gewogene Mengen der einer
frisch bereiteten Mischung der abgewogenen Bestandteile
entnommenen [609] Losung. Andererseits liess sich die ver-
dampfte Menge des Losungsmittels nach bekanntem gaso-
metrischen Gesetze berechnen, wenn man nur den Druck,
unter welchem dasselbe stand, kannte : derselbe ist gleich dem
der reinen Fltissigkeit, vermindert um die abgelesene Er-
niedrigung. Wie ich mich durch direkte Versuche uberzeugte,
genligen die durch Interpolation aus den Regnaultschen
Zahlen erhaltenen Werte fur die reinen Fliissigkeiten voll-
kommen den Anspriichen meiner Versuche. Es sei nun p das
Verhaltnis des in der Fliissigkeit augenblicklich vorhandenen
Losungsmittels zu dem darin aufgelosten Jod; a die einge-
wogene Menge des Losungsmittels in Gramm ausgedriickt,
b die des Jods;/ der berechnete Quecksilberdruck des Gases
Uber der reinen Fliissigkeit, e die gefundene Erniedrigung
gleichfalls in Millimeter Quecksilberhohe ausgedriickt; g das
Gewicht eines Kubikcentimeters des Dampfes bei 0° und
760 mm. Dann haben wir, das Volum der Flasche gleich 270
cc. gesetzt, fur das Gewicht des in dem fliissigen Teil ver-
bliebenen Losungsmittels den Ausdruck

760 . (l+o0

und daher

i
I. p=-

760(1+00

Der weiteren Berechnung lege ich eine Formel zu Grunde,
welche Raoult 1 jiingst aufgestellt hat, die ihrerseits auf dem

1 Zetochr. 2, 372 (1888).

244

MORRIS LOEB

von ihm und Planck 1 ubereinstimmend gefundenen Gesetz
fur die Losungen wenigfliichtiger Substanzen beruht. Diese
Formel lautet

II.

wobei MQ das Molekulargewicht des Losungsmittels, MI
dasjenige des gelosten Korpers bedeutet. In den tabellari-
schen Zusammenstellungen meiner Versuche gebe ich, be-
hufs besserer Uebersicht, in den beiden ersten Kolumnen die
Gewichte der Ingredienzen der eingefiihrten Losung, in der
dritten die Temperaturen, in der vierten die gefundene Er-
niedrigung in Millimeter Quecksilber, in der fiinften den
berechneten Dampfdruck der Losung, in der sechsten die
Werte fur p und endlich das sich ergebende Molekulargewicht
des Jods. Zur Beurteilung der Methode mogen die Mes-
sungen dienen, welche ich an einem Korper von zweifellos
konstantem [610] Molekulargewicht, dem Naphthalin, aus-
gefiihrt: ich schicke dieselben deshalb voraus.

NAPHTHALIN IN SCHWEFELKOHLENSTOFF

a

b

t

e

f-e

P

Ml

5-4082

0-2586

27-5°

9-47

377-09

5-18

129

—

—

27-5

10-93

375 65

5-18

135

Mittel der gefundenen "Werte 132.
Berechnet fur Ci0H8 128.

1 Zeitschr. 2, 408 (1888).

DAS GELOESTE JOD

245

NAPHTHALIN IN AETHER

a

b

t

6

/-

P

Jf,

Mittelwert

2-5990

0 2511

27-5°

32-84

535 55

12-47

150i

2-8359

0-1462

27-5

21-12

557-27

6-53

127

—

—

27-5

21-08

557-31

6 53

128

27-5

21-14

557-25

6-53

127

127-5

—

—

27-5

21-17

557 22

6 53

128

ber. 128

JOD IN SCHWEFELKOHLENSTOFF

a

b

t

e

f-e

P

J/i

Mittel

5-6528

0-4388

27-3°

9 72

373-92

8-37

239

27 3

8-59

375-05

8-37

278

264

—

27 3

8.81

374-83

8-37

271

—

—

27 3

9-08

374-56

8-37

268

5-1862

0-4026

27-5

8-10

378-48

8-46

300-5

300-5

—

—

27-5

8-10

378-48

8-46

300-5

5-4579

0-2594

27-5

4-60

381 • 98

5-15

324

—

—

27-5

4-51

382-07

5-15

332

27-5

4-66

381-92

5-15

320

320

27-5

4-76

381-82

5-15

314

—

—

27-55

4-80

382-52

5-15

310

4-9030

0-2330

27-5

4-67

381-91

5-20

326

326-5

~~

—

27-5

4-60

381-98

5-20

327

Mittelwert aller Versuche J/i = 303 -25 ±5' 10 2
Berechnet ftlr J2, Mt = 254.
" /„ Ml = 381.

1 Dieser Versuch war mit zu konzentrierter Losung angestellt, um in Be-
tracht zu kommen.

2 Der wahrscheinliche Fehler 1st nach der Form el F= ± f
berechnet. Der mittlere wahrscheinliche Versuchsfehler
betragt 19.

+/«'

«

246

MORRIS LOEB

[611] JOB IN AETHER

a

c

t

e

f-e

P

M,

Mittel

3-2578

0-2546

27-2°

8-20

563 69

9-59

488

27-2

7-50

564-39

9-59

534

—

27-2

7-81

564-08

9-59

512

504-7

—

—

27-35

8-09

567-05

9-60

497

—

—

27-3

8-16

565-90

9-60

492-5

3-2864

0-2058

27-3

7-46

566-60

7-68

443

27-3

4-84

569-22

7-68

653

577-2

27-3

5-04

569-02

7-68

642

—

—

27 3

5-66

568-40

7-68

571

3-6809

0 2305

27-4

6-51

569-72

7-50

486-5

—

27-4

6-48

569-75

7-50

487

480-7

—

—

27-45

6-77

570-54

7-51

468-5

3 4343

0-3151

27-5

6 99

571-40

7-62

461

—

—

27-5

7-14

571-25

7-62

451

466-1

—

—

27-5

6-43

571-96

7-62

501-5

—

—

27-5

7-14

571-25

7-62

451

Mittel aller Versuche Ml = 507'2±10'5.
Wahrscheinlicher Fehler ernes Versuchs = 42.
Berechnet fur J4, M^ = 508.

Aus diesem Material ergiebt sich mil grosser Wahrschein-
lichkeit, dass das Jod in roter Losung ein der Formel 7 4 ent-
sprechendes Molekulargewicht besitzt, wahrend sich aus der
Schwefelkohlenstofflosung ein halbwegs zwischen 72 und 73
stehender Wert berechnet. Um den Vergleich mit andern
Berechmmgsweisen zu erleichtern, mache ich noch darauf
auf merksam, dass meine Werte fur p bei Aetherlosungen un-
gefahr einer Molekel 74 auf hundert Molekel des Gemenges
entsprechen, wahrend in den Schwefelkohlenstofflosungen
das Verbal tnis zwischen 1 : 100 und 2 : 100 schwankte. Dass
sich grossere Verdiinnungen bei dieser, sowie der Raoultschen
Versuchsordnung verbieten, wird klar, wenn man bedenkt,
dass der Wert e in der Berechnung dreimal auftritt und man
denselben daher nicht sich so verkleinern lassen darf , dass die

DAS GELOESTE JOD 247

Beobachtungsfehler verhaltnissmassig bedeutend werden.
Es ware daher, wie schon Raoult beiuerkt, iiberhaupt die
Gefrierpunktsmethode der Dampfspannungsmethode immer
vorzuziehen. Um das mir vorgesteckte Ziel zu erreichen,
fehlte es mir aber vor allem an einem gefrierbaren Losungs-
mittel, welches das Jod mit reinvioletter Farbe loste; Benzol
giebt, wie schon erwahnt, eine Mischfarbe. Trotzdem habe
ich im Verlaufe der Untersuchung Versuche iiber die Gefrier-
punkte der Losungen von Jod in Benzol sowohl, [612] wie in
Eisessig angestellt. Ich gab dieselben aber auf, als ich mich
Uberzeugt, dass bei der sehr geringen Loslichkeit des Jods in
den erwahnten Fllissigkeiten ein geniigender Spielraum nicht
vorhanden ist: das berechnete Molekulargewicht nahm von
der aussersten Verdiinnung bis zur Sattigung stetig mit der
Konzentration zu, so dass sich kein Punkt zeigte, bei welchem
man einen Vorzug iiber die andern erkennen konnte. Die
jiingst von den Herren Paterno und Nasini 1 veroffentlichten
Zahlen scheinen mir Aehnliches zu ergeben.

Herrn Professor Ostwald freue ich mich fur das liebens-
wiirdige Interesse, welches er mir wahrend dieser unter
seiner Leitung ausgefiihrten Arbeit gezeigt, hier offentlich
danken zu diirfen.

1 Berichte, 21, 2155 (1888).

[812] THE USE OF ANILINE AS AN ABSORB-
ENT OF CYANOGEN IN GAS ANALYSIS1

IN a paper published in the "Comptes Rendus," 100,
1005, some time ago, Jaquemin proposed the use of aniline
as an absorbent for cyanogen in quantitative gas analysis,
without, however, giving details of any experiments as to the
trustworthiness of the method. The proposal is a surprising
one, considering that hydrogen cyanide is always formed in
the preparation of cyananiline; this fact is distinctly stated
by Hofmann,2 who accounted for its production by certain
secondary reactions which he studied. It is also to be noted
that Jaquemin, in the same paper, describes a very satisfac-
tory method of preparing cyanogen gas in the wet way, and
that he probably employed the moist cyanogen in his experi-
ments with aniline. As the presence of water seems to favor
most of the reactions of cyanogen, there did not seem to be
any conclusive evidence that dry cyanogen would be totally
absorbed by aniline. At all events, it seemed worth while to
make the experiment with cyanogen prepared in the old way,
and at the same time to ascertain to what extent the develop-
ment of hydrocyanic acid would interfere with Jaquemin's
proposed method for gas analysis. For this purpose, cyano-
gen prepared from dry mercuric cyanide was brought into
contact with recently distilled aniline. The gas was, indeed,
absorbed rapidly and completely, nor did a bubble of gas
appear after twenty-four hours' standing. But as soon as car-
bon dioxide was passed in, the presence [813] of hydrocyanic

1 Reprinted from Journal of the Chemical Society, 63, 812 (October, 1888).

2 Hofmann, Annalen, 66, 129 (1848).

ANILINE AS ABSORBENT OF CYANOGEN 249

acid became apparent. It was expelled from the aniline by
the carbon dioxide, and could now be recognized both by its
odor and by the Prussian blue reaction. At the same time a
considerable quantity of carbon dioxide is absorbed by the ani-
line and must be held in solution, as chemical union is impos-
sible under the circumstances. As the same is said to be the
case with carbon monoxide, and these two gases are those
which generally accompany cyanogen, I fail to see how aniline
can be generally useful in determining the amount of cyano-
gen in a mixture, apart from the fact that hydrogen cyanide
is produced in the reaction, and is itself very loosely attracted
by aniline.

The experiments by which I satisfied myself of this were
made last April, in the laboratory of the Physical Association
of Frankfort-on-Main, to the director of which, Dr. B. Lep-
sius, I am very much indebted. The details of a few of the
most important tests are given below.

I. 32*88 cc. of cyanogen gas (under standard conditions)
were absorbed immediately by 12*5 cc. aniline; after twenty-
five hours no trace of gas had been evolved.

II. A mixture of cyanogen and dry air was introduced into
a T-shaped eudiometer, provided with stopcocks and filled
with mercury. Aniline was first added and allowed to absorb
the cyanogen, and dry carbon dioxide was then passed in;
when no further change took place, the unabsorbed gas was
transferred to a test-tube over mercury, and brought in con-
tact with a few drops of sodic hydrate; the alkaline solution
gave an appreciable test for hydrocyanic acid with ferrous
and ferric salts. In the table [on the following page] the
measurements and the results are given: —

250

MORRIS LOEB

t

B

cc

Corrected

Volume of cyanogen and air . .
Volume 22 hours after introduc-
ing aniline

19-0°
19-5

752-1
752-1

60

7-7

55-34
7-09

-

Volume of cyanogen absorbed .
After addition of carbon dioxide
Volume carbon dioxide

19~5

752-1

36-75

33~84

48-25
26-75

After 23 '5 hours . ...

19-5

752-0

21-00

19 33

Volume carbon dioxide absorbed

14-51

III. A similar experiment, performed in a somewhat dif-
ferent order, and with the use of a straight eudiometer, gave
an analogous result. H =the height of the column of mercury,
h = the height of the column of aniline reduced to mercury.

[814]

t

B

H

n

cc

Corrected

Volume of carbon dioxide ....
Volume of carbon dioxide and
cyanogen ...

19-5°
19-5

752-1
752-1

-

-

56-5

108-5

52-03
99-91

Volume of cyanogen ....

47'88

Vol. 22 hours after introduction
of aniline ....

19-5

752-0

227

5-3

43-0

27-32

Volume of gas absorbed

72-59

47*88 cc. cyanogen gas and 24*71 cc. carbon dioxide have,
therefore, been absorbed. In this case, too, the residual gas
had a decided odor of prussic acid.

[948] ZUR KINETIK DER IN LOSUNG BEFIND-
LICHEN RORPER1

1. ElNLEITUNG

BEKANNTLICH hat Herr Fr. Rohlrausch,2 ausgehend von
der Hittorfschen Hypothese, wonach die Ueberfiihrungszahl
einer Losung das Verhaltnis der Geschwindigkeiten der beiden
Jonen, in welche das in Losung befindliche Salz zerfallt,
berechnen lasst, zwischen dieser Grosse und dem elektrischen
Leitungsvermogen eine einfache Beziehung aufgestellt. Hier-
nach ist das Leitungsvermogen X eine additive Eigenschaft,
namlich gleich der Summe der Beweglichkeiten des Anions
v und des Rations u. Die Ueberfiihrungszahl eines Jons ist das
Verhaltnis der Beweglichkeit dieses Jons zu der Summe der
Beweglichkeiten der beiden Jonen. Es ist somit, wenn n die
Ueberfiihrungszahl des Anions, und somit l—n dieselbe
Grosse fur das Ration bedeutet: —

~ u

l-n=-

u+v u+v

Diese Beziehungen fand Herr Rohlrausch an einer Anzahl
Verbindungen einbasischer Sauren sowie an einigen ein-
wertigen Basen in Losungen geringer Ronzentrationen gut
bestatigt; schwache Basen (z. B. Ammoniak) und Sauren
(z. B. Essigsaure) fiigten sich selbst bei betrachtlichen Ver-
diinnungen auch nicht naherungsweise unter obige Gesetze.

Diesen Widerspruch zwischen Theorie und Erfahrung hat
kiirzlich Herr Arrhenius 3 durch Einfiihrung des Aktivitats-
begriffes gehoben. Das Leitungsvermogen kann nur in dem

1 In collaboration with W. Nernst. Reprinted from Zeitschr. 2, 948 (1888).

2 Fr. Kohlrausch, Wied. Annalen, 6, 1 (1879). Ibid., 26, 213 (1885).

1 Arrhenius, Sur la conductibilite, etc. Stockholm, 1884. Zeitschr. 1, 631 (1887).

252 MORRIS LOEB

Falle eine additive Eigenschaft sein, wenn in alien Verbin-
dungen die Jonen sich samtlich oder mit einem [949] kon-
stanten Bruchteil an der Leitung beteiligen. Nach der Theo-
rie von Arrhenius ist dieses nicht der Fall. Die Elektrizitats-
leitung wird nur von den aktiven Molekeln iibernommen;
der Aktivitatskoeffizient, d. h. das Verhaltnis der leitenden
zu den insgesamt vorhandenen Molekeln variiert nicht nur
bei den verschiedenen Verbindungen, sondern er ist auch bei
derselben Verbindung von der Konzentration abhangig,
dergestalt, dass er mit der Verdunnung wachst und bei
grosser Verdunnung dem Grenzwerte 1 zustrebt. Kohl-
rauschs Gesetz erlangt daher hiernach im allgemeinen erst
bei sehr kleinen Konzentrationen strenge Giiltigkeit. Die
gute Uebereinstimmung, welche man 1. c. S. 215 : findet,
riihrt daher, dass die daselbst aufgefiihrten Verbindungen bei,
der Konzentration f0 normal, auf welche sich die Leitungs-
vermogen und Ueberfiihrungszahlen beziehen, einen nahe
gleichen Aktivitatskoeffizienten, etwa 0.88, besitzen. Uebri-
gens sei darauf hinge wiesen, dass auch Herr Kohlrausch
selber 2 seinem Gesetze eine naherungsweise Giiltigkeit
zuschrieb und eine Untersuchung zur Prlifung desselben bei
grossen Verdlinnungen fur wiinschenswert hielt. Eine neuere
Untersuchung von Herrn Ostwald,3 in der die Leitvermogen
einer grossen Anzahl Elektrolyte bis zu sehr bedeutenden
Verdtinnungen untersucht wurden, hat bereits ein diesen
Anschauungen gunstiges Resultat geliefert.

Den physikalischen Unterschiede zwischen den aktiven
und inaktiven Molekeln hat Herr Arrhenius bekanntlich
in Weiterfiihrung der Clausius-Williamsonschen Hypothese
darin gefunden, dass jene in ihre mit gleich grosser aber ent-
gegengesetzter Elektrizitat geladene Jonen dissociiert sind,

1 Kohlrausch, Wied. Annalen, 26, 215 (1885). J Loc. cit. S. 216 (1885).

8 Ostwald, Zeitschr. 1, 61 und 97 (1887).

KINETIK DER GELOSTEN KORPER 253

wahrend bei letzteren der elektropositive und negative Be-
standteil in ihrem Bewegungszustande nicht von einander
unabhangig sind.

Urn nun Kohlrauschs Gesetz von diesen veranderten Ge-
sichtspunkten aus zu prlifen, fehlt es vor allem an geniigen-
den Untersuchungen der Ueberf iihrung, woriiber in anbetracht
der Wichtigkeit, welche die genaue Kenntnis dieses Phano-
mens f lir die Mechanik der Elektrolyse und die Konstitution
der Losungen besitzt, Uberraschend wenige Arbeiten vorlie-
gen. Seit den klassischen Untersuchungen von Herrn Hit-
torf 1 haben nur vereinzelt Forscher 2 Messungen hieriiber
angestellt. In der Absicht, zur Ausf tillung dieser Liicke in der
Wissenschaft beizutragen und eine Priifung obigen Gesetzes
an sehr verdiinnten Losungen zu ermoglichen, haben wir an
einer Anzahl Saureradikale, hauptsachlich organischer Na-
tur [950], durch, gleichzeitige Messungen der Ueberf iihrung
und der Leitfahigkeit von Silbersalzen die Jonenbeweglich-
keiten zu ermitteln gesucht, deren Kenntniss, wie einer von
uns zu zeigen gesucht hat, auch fur andere Phanomene von
Wichtigkeit zu sein scheint.3 Auch haben wir einige Bestim-
mungen ausgefiihrt, welche liber die Frage nach dem Einfluss
der Temperatur 4 auf die Wanderungsgeschwindigkeiten
orientieren soil ten.

Fur die Wahl des Silbers als positives Jon sprachen eine
Anzahl Griinde; zur Bestimmung des Grenzwertes desmole-
kularen Leitvermogens empfahl sich im Interesse der gros-
seren Sicherheit ein einwertiges Jon, und Silber ist das ein-
zige einwertige Metall, welches sich — ein grosser Vorteil bei

1 Hittorf, Pogg. Annalen, 89, 177. 98, 1. 103, 1. 106, 337.

1 G. Wiedemann, Pogg. Annalen, 99, 177. Kirmis, Wied. 'Annalen, 4, 503.
Weiske, Pogg. Annalen, 103, 466. Kuschel, Wied. Annalen, 13, 289. Lenz, Mem.
de St. Petersb. 30, 1882.

• Nernst, Zeitschr. 2, 613 (1888).

4 Nernst, Ibid. 623 (1888).

254 MORRIS LOEB

derartigen Messungen — bequem als Elektrode verwenden
lasst. Seine Salze sind leicht in geniigender Reinheit zu
beschaffen. Sodann bot sich uns in der eleganten Titrier-
methode auf Silber von Herrn Volhard 1 die Moglichkeit, die
notigen Analysen mit grosser Leichtigkeit und durchaus
geniigender Sicherheit auszufuhren.

2. APPARAT ZUR BESTIMMUNG DER UEBERFUHRUNGS-

ZAHL

Bei der Wahl desselben suchten wir die Anwendung von
Membranen zu umgehen, um storende Nebenwirkungen
vollig zu vermeiden, und waren darauf bedacht, seinen innern
Widerstand moglichst gering zu machen, damit bei den sehr
verdiinnten Losungen, mit denen wir arbeiteten, die Zeit-
dauer eines Versuchs nicht iibermassig sich ausdehne. Wir
sind schliesslich nach mehreren Versuchenbei einemApparate
stehen geblieben, welcher bei seiner Einf achheit sich in vielen
Fallen als brauchbar erweisen diirfte. Er besitzt im wesent-
lichen die Form einer Gay-Lussacschen Burette und ist in
nebenstehender Zeichnung dargestellt. Um das lastige Her-
abfallen des an der Kathode sich niederschlagenden Silbers
zu vermeiden, ist ein seitliches Ansatzrohr — von derselben
Weite wie das Hauptrohr — angeschmolzen, welches in einer
Kugel endigt, die zur Aufnahme der Kathode dient [951],
Eingefiihrt wird dieselbe durch das engere Rohr B; sie
besteht aus einem an einem Silberdraht befestigten und
cylindrisch gerollten Silberblech. Die Anode, ein an seinem
untern Ende spiralformig gewickelter Silberdraht, wird durch
A eingefiihrt und reicht bis auf den Boden des Gefasses. Um
den Eintritt des Stromes in die Losung nur am unteren Ende
zu ermoglichen, ist der gerade Teil des Drahtes mit einer
diinnwandigen Glaskapillare iiberzogen, die sich trotz des

1 J. Volhard, Annalen, 190, 1 (1878). ,

KINETIK DER GELOSTEN KORPER 255

verschiedenen Ausdehnungskoeffizienten von Silber und Glas

gut an den Draht anschmelzen liess. Die Oeffnungen A und

B tragen durchbohrte, von kurzen

Glasrohrchen durchsetzte Korke.

Das Rohrchen bei A lasst den Elek-

trodendraht einfach hindurch-

gehen, wahrend dasjenige bei B

einen seitlich eingeschmolzenen

Platindraht besitzt, an welchem

die Elektrode aufgehangt wird.

Es kann so A durch ein iiber

Draht und Rohrchen gezogenes

Endchen Gummischlauch mittelst

Quetschhahn verschlossen, bei B

mittelst eines Gummischlauchs

gesaugt oder geblasen werden,

ohne die Elektroden zu erschiittern.

Bei Ausfiihrung eines Versuchs wurde nun ein solcher
Apparat samt Elektroden und Korken, aber ohne die Gum-
miverbindungen, gewogen; A alsdann in erwahnter Weise
geschlossen und bei B gesaugt, wahrend die Miindung von
C unter die Oberflache der betreffenden Losung tauchte. Der
Apparat fiillte sich so bis zur Hohe der oberen Wand des An-
satzrohrs und enthielt, je nach Grosse, 40 oder 60 cc. Losung.
Nunmehr wurde das Ausflussrohr ebenfalls durch ein Gum-
mikappchen verschlossen, der Apparat aufrecht in einen
Wasserthermostaten nach Herrn Ostwald 1 gehangt und,
nachdem die Temperatur sich ausgeglichen hatte, die Strom-
leitung angelegt. Sofort nach Beendigung der Elektrolyse
wurde das Ausflussrohr geoffnet und durch Anblasen bei B
beliebige Teile der Losung in tarierte Gef asse gefiillt, gewogen
und analysiert. Die Menge der im Apparate verbleibenden

1 Ostwald, Zeitschr. 2, 565 (1888).

£56 MORRIS LOEB

Losung wurde durch die Gewichtszunahme desselben be-
stimmt. Wenn nun wahrend des Versuchs keine Mischung
durch Diffusions- oder Konvektionsstrome stattgefunden
hat, so wird bei passender Einteilung die zuerst auslaufende
Schicht die konzentriertere Losung an der Anode, sowie
gentigende Menge unveranderte Losung enthalten, um voll-
standig nachzuspiilen. Die folgenden Schichten miissen eine
unveranderte Konzentration zeigen, wahrend der im Apparat
zuriickbleibende Anteil die verdiinnte Losung um die Kathode
enthalt. Die Probe dafiir, dass der Versuch brauchbar war,
lag also sowohl in dem Unverandertsein der mittleren Schich-
ten, wie darin, dass die Losung um die Kathode ebensoviel
[952] Silber verloren hatte, als diejenige um die Anode mehr
enthielt. Nachdem wir die erste Bedingung stets erfiillt
gefunden hatten, verzichteten wir schliesslich imlnteresse der
schnelleren Ausflihrung der Versuche auf die Entnahme der
mittleren Schichten und begnligten uns, die Losung in zwei
etwa gleiche Portionen zu teilen. Wenn, wie es haufig vorkam,
ein Wachsen des niedergeschlagenen Silbers von der Kugel
aus das Ansatzrohr entlang stattfand, so wurde der Versuch
unterbrochen, ehe das Hauptrohr erreicht war.

Die Analysen wurden, wie oben erwahnt, mittels Titra-
tion durch Rhodanammoniumlosung ausgefiihrt, deren Ge-
halt (etwa ^ normal) durch of tmaligen Vergleich mit einer
Silbernitratlosung ermittelt wurde. Der Titer der letzteren
wurde im Laufe der Untersuchungen mehrmals gewichts-
analytisch bestimmt und stets unverandert gefunden. Die
Titrationen konnen eine Genauigkeit bis auf gut §5 cc.[ =0-038
mg Ag] beanspruchen, besonders da zur Kontrolle der Farben-
umschlag stets doppelt beobachtet wurde; es wurde namlich
nach Eintreten der ersten Farbung noch aus einer Pipette
1 cc. i^o AgNO3 Losung zugeftigt und wiederum der Farben-
umschlag beobachtet.

KINETIK DER GELOSTEN KORPER 257

In die TJeberfiihrungszahl geht ausser der Menge des iiber-
fiihrten noch die des gleichzeitig ausgeschiedenen Silbers
ein, zu deren Bestimmung man sich bekanntlich am einfach-
sten eines in den Stromkreis eingeschalteten Silbervolt-
ameters bedient. Da dieselbe aber haufig bei der Unter-
suchung verdiinnter Losungen weniger als 20 mg betrug,
eine so geringe Quantitat bei dem schwer vollig zu vermei-
denden Verlust kleiner Silberflitterchen sich nicht mit einer
geniigenden Genauigkeit bestimmen lasst, so haben wir die
Elektrizitatsmenge, welche wahrend der Elektrolyse den
Apparat durchfloss, durch galvanometrische Messung ermit-
telt. In den Stromkreis (s. Fig.) wurde ein Stopselrheostat
eingeschaltet, an dessen Enden sich ein Nebenkreis an-
schloss, welcher ein Galvanometer mit direkter Ablesung und
ein Clark-Element enthielt. Durch richtige Wahl des aus
dem Rheostaten eingeschalteten Widerstandes W, sowie
passende Schaltung des Elements, kann bekanntlich stets
das Galvanometer stromlos gemacht werden; dann ist die

ri

Intensitat im Hauptkreis i=yy> wo E die elektromotorische

Kraft des Normalelementes bedeutet. Da wahrend der
Dauer der Elektrolyse, gewohnlich 4 bis 5 Stunden, die
Stromintensitat sich wenig und zwar ausserordentlich stetig
sich anderte, so geniigte es, eine derartige Strommessung,
welche sich in wenigen Sekunden ausfiihren Hess, alle zehn
Minuten vorzunehmen, um das Stromintegral mit weitaus
geniigender Sicherheit in der bekannten Weise zu berechnen.
[953] Durch besondere Versuche ergab sich, dass, wenn
Widerstandskasten und Element eine Temperatur von 18°
besassen, die ausgeschiedene Silbermenge/ sich aus der Formel

/= 96-29-
w

258 MORRIS LOEB

berechnen lasst; hier bedeutet z die Zeitdauer der Elektrolyse
in Minuten, und w den berechneten Widerstand, der, wenn
wahrend dieser Zeit die gleiche Elektrizitatsmenge in kon-
stantem Strome den Apparat durchflossen hatte, eingeschaltet
werden miisste, um das Galvanometer stromlos zu machen.
Betrug die Temperatur von Element und Kasten t, so war
obige Zahlmit 1-0.0012 (2—18) zu multiplizieren, wobei sich
der Temperaturkoeffizient 0.0012 aus dem des Elements,
—0.0008, und dem des Kastens, +0.0004, zusammensetzt.

Aus der Thatsache, dass nach Herrn Kohlrausch l ein
Amper per Sekunde 1.118 mg Ag zersetzt, und der Angabe,
dass die Einheit unseres Kastens das legale Ohm war, ergiebt
sich (die absolute Widerstandseinheit = 1.063 SE gesetzt)
die elektromotorische Kraft unseres Clark-Elementes bei
18° zu 1.431 Volt. Die Zahl stimmt gut mit den Angaben
der Herren Lord Rayleigh (1.434 bei 15°) und v. Ettings-
hausen 2 (1.433 bei 13.5°). Auf 18° umgerechnet, geben letz-
tere Werte 1.431 und 1.428, und beweist die Uebereinstim-
mung unserer Zahl mit diesen, dass wir in der That im Clark-
Element einen Etalon fiir eine elektromotorische Kraft be-
sitzen, bei dessen Anwendung man Fehler iiber 2 pro mille
kaum wird begehen konnen.

Als Stromquelle dienten uns 38 Leclanche-Elemente,
deren elektromotorische Kraft zusammen etwa 40 Volt
betrug und welche einen innern Widerstand von etwa 120
Ohm besassen. Um das Auswachsen des Salmiaks zu ver-
meiden, waren die oberen Rander der Batterieglaser und der
Kohlenstabe mit Paraffin iiberstrichen. In einen Widerstand
von 5 bis 10000 Ohm geschlossen, liefert die Batterie Stunden
lang einen durchaus konstanten Strom und bietet dieselbe
ausserdem den Vorteil, stets zum Gebrauch bereit zu sein.

1 F. Kohlrausch, Leitf. d. prakt. Physik, 327 (1887).

2 Wiedemann, Elektrizitat, 4, 985 (1885). j

KINETIK DER GELOSTEN KORPER 259

3. DABSTELLUNG DER LOSUNGEN l

Die Losung von Silbernitrat (AgNO3) wurde durch Auf-
losung des krystallisierten Salzes erhalten. Die Silbersalze
der Chlorsaure (AgClO3), [954] Ueberchlorsaure (AgClO4),
Aethylschwefelsaure (AgO4SC2H5), Naphthalinsulfonsaure
(AgO3SCioH7), Benzolsulfonsaure (AgO3SC6H5), Pseudo-
kumolsulfonsaure (AgOsSCgHn), Essigsaure (AgO2C2H3)
wurden durch Abstumpfung der freien Sauren mit feuchtem
Silberoxyd und nachheriges Filtriern durch Asbest darge-
stellt. Dithionsaures Silber (Ag2S2O6) wurde durch Wech-
selzersetzung aquivalenter Mengen Baryumdithionat und
Silbersulfat gewonnen. Um Kieselfluorsilber (Ag2SiFl6)
zu erhalten, wurde in eine Losung von Fluorkieselsaure so
viel Silberoxyd eingetragen, als dieselbe aufnehmen wollte;
darauf wurde so lange Baryumhydratlosung zugetropfelt,
bis sich zu dem niederfallenden Baryumfluorsilikat etwas
braunes Silberoxyd gesellte. Die neutrale Losung wurde
filtriert und auf die gewiinschte Verdlinnung gebracht.

4. AUSFUHRLICHE MlTTEILUNG EINES VERSUCHS ALS
BEISPIEL

Derselbe wurde bei einer Temperatur von 26° mit etwa
i^o normaler Silbernitratlosung ausgefiihrt, welche nach Be-
endigung der Elektrolyse in vier Schichten geteilt wurde.
In der folgenden Tabelle befindet sich unter I die Gewichts-
menge der Schichten, unter II die darin gefundene Menge
Silber, unter III die Silbermenge, welche darin ohne Elek-
trolyse enthalten gewesen ware und sich aus der Angabe
berechnet, dass 1 g Losung 1.139 mg Ag enthielt.

1 Dieselbe 1st von M. Loeb ausgefiihrt.

260 MORRIS LOEB

TAB. 1.

Nr.

I

II

III

Diff.

1
2

20-09 g

5-27

39 • 66 mg
5-96

22-88mg
6-00

+16.78
-0-04

3

5-38

6-04

6-07

-0-03

4

27-12

14-14

30-89

-16-75

57-81 65-80

Wie man sieht, 1st der Gehalt der beiden mittleren Schichten
2 und 3 innerhalb der Analysenf ehler unverandert geblieben;
auch das zweite Kriterium fiir die Brauchbarkeit des Ver-
suchs,'dass namlich der aus dem Versuche berechnete von
dem direkt gefundenen Gehalt nicht differiert, sehen wir sehr

ftfr Of\

nahe erfullt, indem aus - - =1.138 ein demob igen direkt

57.81

bestimmten 1.139 nahe kommender Wert sich ergiebt.

Aus der Strommessung in der angegebenen Weise berechnete
sich die der durch den Apparat geflossenen Elektricitats-
menge aquivalente Silbermenge zu 32.10 mg, wahrend in
einem zur Kontrolle gleichzeitig eingeschalteten [955] Silber-
voltameter 32.2 mg sich vorfanden; der erstere Wert, als
der zuverlassigere, wurde angenommen.

Die Ueberf iihrungszahl ist aus obigen Daten nach Hittorf x
folgendermassen zu berechnen. In die Losung um die Anode
(1) sind 32.1 mg Ag ein, aus der um die Kathode (4) ebenso-
viel ausgetreten. Vor der Elektrolyse fiihrten(l -0.0011390) g
Wasser 1.139 mg Ag, wo v das Vernal tnis des Molekular-
gewichts des Silbernitrats zu dem Atomgewicht des Silbers,

170

—— = 1.57, bedeutet. Nach der Elektrolyse waren an der

108

Anode (20.09-0.03966 v) g Wasser mit 39.66 mg Ag, an der
Kathode (27.12-0.01414 v) g Wasser mit 14.14 mg Ag ver-

* Pogg. Annalen, 98, 19 (1856).

KINETIK DER GELOSTEN KORPER 261

bunden. Die Lfisung um die Anode ist somit um 39.66-
(20.09-0 03966 .)

^07 i o_o
mg Ag reicher, diejenige um die Kathode un

1-0.001139 v

1.139-16.82 = (27.12Xll.39-16.82) (1+0.001139 v) mg Ag
armer geworden, indem das kleine Defizit der mittleren
Schichten zu dem Mindergehalt von Nr. 4 hinzugefiigt ist.
Wie man sieht, geben die in Tabelle 1 angefiihrten Differen-
zen, welche den ersten Faktoren der beiden obigen Produkte
entsprechen, nicht genau die Menge der Zu- resp. Abnahme
von Ag an, sondern sind mit einem Korrektionsglied be-
haftet, welches jedoch fiir Losungen so geringer Konzentra-
tion sehr klein ist. Die Ueberfiihrungszahl, bezogen auf das
Anion NO3, folgt also zu

1.0017, resp. ^^ 1.0017, im Mittel 0.524.

32.10 32.10

Nachdem wir wiederholt ein ahnlich giinstiges Resultat
betreffs des Unverandertseins der mittleren Schichten ge-
funden batten, wurde, wie schon erwahnt, schliesslich die
Losung aus dem Apparate meistens in nur zwei Portionen
geteilt untersucht.

Da bei dem eben mitgeteilten Versuch in den Stromkreis
gleichzeitig noch ein zweiter Apparat eingeschaltet war, so
betrug die mittlere Stromintensitat nur etwa 0.0012 Amper,
die Versuchsdauer 7 Stunden. Im Interesse des sehnelleren
Arbeitens und um die Batterie mehr auszunutzen, zogen wir
es in den meisten Fallen vor, zwei Apparate neben einander
zu schalten, wo dann natiirlich jeder der beiden Hauptkreise
behufs Strommessung einen eigenen Rheostaten enthielt;
durch eine geeignete Schaltung wurde dann der Nebenkreis
bald an den einen, bald an den anderen [956] Widerstands-
kasten angelegt, und so in jedem Kreise der Strom gemessen;

MORRIS LOEB

bei der so erzielten doppelten Intensitat sank die Versuchs-
dauer auf 3 bis 4 Stunden. Es sei noch erwahnt, dass wir, um
ganz sicher zu gehen, das benutzte Clark-Element haufig mit
einem zweiten verglichen; die absolute Gleichheit der elektro-
motorischen Krafte beider lehrte, dass sich das benutzte
Element nicht wahrend der Versuche anderte.

5. MESSUNGEN DER UEBERFUHRUNGSZAHL

Im folgenden bedeutet t die Versuchstemperatur; m den
Molekulargehalt der Losung (Grammaquivalente pro Liter) ;
/i die aus der Strommessung berechnete Silbermenge in Milli-
grammen, welche sich im Apparat wahrend des Versuchs
ausschied;/2 dieselbe Grosse, wiesie sich im Silbervoltameter,
welches oft gleichzeitig eingeschaltet, vorfand; n die Ueber-
fiihrungszahl, bezogen auf das Anion. Dem Werte von n ist
stets derjenige fur f\ zu Grunde gelegt.

Salpetersaures Silber

1)2 = 20°. m = 0-1043. / = 83'5. /. = 83'6. n = 0'528.

2)* = 26°. m = 0-0521. /! = 76-7. 7i = 0'524.

3)2 = 26° m = 0-025. /t = 48'0. n = 0'5223.

4)^ = 0°. 7/1 = 0-025. /t = 48-0. n = 0-5383.

5)2 = 26°. m = 0-0105. /1 = 32'10. /, = 32-2. n = 0-524.

6)2 = 26°. m = 0-0105. /t = 32'10. /, = 322. n = 0'521.

Bei 3) und 4), sowie bei 5) und 6) waren die Apparate in
denselben Stromkreis gleichzeitig eingeschaltet.

Chlorsaures Silber

1) 2 = 24-8°. w = 0-0245. /.=39-88. /2=39'5. ?i = 0-503.

2) t = 24-8°. m = 0-0245. /j = 51'72. n = 0'499.

Ueherchlorsaures Silber

1)^ = 24-8°. w = 0-0247. /. = 89-88. /2 = 39'5. n = 0'515.
2) t = 24-8°. m = 0-0247. f, = 51'72. n = 0-512.

Bei der Untersuchung dieser beiden Losungen befand sich
1) mit 1) und 2) mit 2) je im gleichen Stromkreis.

AetJiylschwefelsaures Silber

1) t = 24-8°. m = 0-0243. /, = 53-30. n = 0-385.

2) t = 24-8°. m = 0-0243. f, = 48'47. /2 = 48'34. n = 0-389.
3)2 = 25-0°. m = 0-00606. /t = 18- 10. n = 0-384.

KINETIK DER GELOSTEN KORPER 263

NapJithalinsulfonsauret Silber

1) t = 29-2°. m = 0-01292. /. = 33'95. n = 0-390.

2)* = 25-0°. m = 0-0250. ^ = 39-75. /2 = 39'5. n = 0'386.

[957] Benzolsulfonsaures Silber

1) t = 24-8°. m = 0-0250. /, = 48-47. /, = 48'34. n = 0-343.

2) £ = 24'7°. m = 0-0250. /x = 17'85. 71 = 0-351.

Pseudokumolsulfonsaures Silber

1) t = 24-2°. m = 0-0238. /. = 61-62. n = 0'293.

2) t = 29-2°. m = 0-02216. /t = 38'24. n = 0'2947.

3) t = 0°. m = 0-02216. /t = 38'24. n = 0'2732.

4) *= 0°. m = 0-02216. /; = 42-79. n = 0-2731.

Bei 2) und 3) befanden sich die Apparate im gleichen Strom-
kreis.

Essigsaures Silber

Bei der Untersuchung dieses Salzes zeigten sich Schwierig-
keiten, indem nach Schluss des Versuches die mittelste
Schicht nicht unverandert blieb, und der aus dem Versuch
sich ergebende Titer der Losung nicht gut mit dem direkt
gefundenen iibereinstimmte. Es ist nicht unwahrscheinlich,
dass diese Unregelmassigkeiten mit der geringen Loslichkeit
des Salzes zusammenhangen, indem sich leicht an der Anode
die Losung so konzentrieren kann, dass festes Salz ausfallt
und sich im Laufe des Versuchs zersetzt. Schliesslich gelang
es, mit sehr verdlinnter Losung anscheinend brauchbare
Resultate zu erhalten.

1) * = 25°. m = 0-00972. f, = 20'80. n = 0'375.

2) t = 24°. m = 0-00972. /t = 23'99. n = 0'377.

Von Salzen zweibasischer Sauren wurden untersucht: —

Dithionsaures Silber

1)^ = 24-8°. m — 0-0246. /t = 33'40. n = 0*604.

2) t = 29-2°. m = 0-0246. /, = 46'70. n = 0'604.

8)*= 0°. m = 0-0246. /1 = 46'70. n = 0'605.

4)^ = 24-2°. m = 0-0246. /t=48-85. n = 0'606.

5) t = 0°. m = 0-0246. /j = 45'80. n = 0'603.

Bei 2) und 3) waren die Apparate im gleichen Stromkreis
hintereinander geschaltet.

264 MORRIS LOEB

Kieselfluorsilber

1) £ = 22 2°. 771 = 0-02815. /x = 60'28. n = 0'467.

2) £ = 22-2°. w = 0-02815. /x = 37'44. n = 0'464.

In Tabelle 2 sind die gewonnenen Resultate der Ueber-
fiihrungszahlen n nebst den dazugehorigen Temperaturen
und Konzentrationen zusammengestellt :

[958] TAB. 2.

n t m

Salpetersaures Silber 0-523 25° n1 n n1

0-539 0°

Chlorsaures " 0'505 25° 0*0245

Ueberchlorsaures 0'514 25° 0'0247

Aethylschwefelsaures " 0-385 25° 0 • 0243— 0 • 0061

Naphthalinsulfonsaures " 0'390 30°

0-386 25°

Pseudokumolsulfonsaures " 0-293 25° A.AOQ

0-273 0°

Benzolsulfonsaures " 0-347 25° 0-025

Essigsaures " 0-376 25° 0"0097

Dithionsaures 0'604 25°

0-604 0°

0-0246

Kieselfluorwasserstoffsaures 0'466 22° 0*0282

Salpetersaures Silber ist eingehend bereits von Herrn Hittorf 1
untersucht worden, welcher etwa vom Gehalte 0.3 ab warts
bis 0.024 die Ueberfiihrungszahl ungeandert, im Mittel
0.526 bei 19° fand. Wir finden das gleiche Ergebnis bei Varia-
tion des Titers von 0.1-0.01 und einen dem Hittorfschen
sehr nahen Wert, namlich 0.527 auf die gleiche Temperatur
umgerechnet. Audi obiger Wert fiir Silberacetat stimmt gut
mit dem Hittorfschen (0.373 bei 2 = 15° und m=0.05).

6. LEITVERMOGEN DER SILBERSALZE 2

Dasselbe wurde bei 25° nach der Kohlrauschschen Methode
mittelst Telephon und Messbriicke bestimmt. Die Losungen
vom Gehalte m= 0.025 -0.01 wurden in einem vom Wasser-
bade eines Thermostaten umgebenen Widerstandsgefass

1 Pogg. Annden, 89, 199 (1853).

2 Diese Messungen sind von W. Nernst ausgefiilirt.

KINETIK DER GELOSTEN KORPER 265

nach Herrn Arrhenius l untersucht und durch wiederholtes
Verdiinnen auf die Halfte, wie von Herrn Ostwald beschrie-
ben, bis auf etwa 0.0008 gebracht. Die unten mitgeteilten
Zahlen beziehen sich auf das Leitungsvermogen von Queck-
silber = l, indem die von Herrn Kohlrausch bei 18° fur Silber-
nitrat beobachteten Leitvermogen 2 der Berechnung zu
Grunde liegen. Zur grosseren Sicherheit der Umrechnung
wurde zwischen 18° und 25° der Temperaturkoeffizient bei
den Gehalten m=0.1, 0.02, 0.005 bestimmt und zu 0.0213,
0.0217, 0.0222 gefunden. Der Wert von Herrn Kohlrausch,3
0.0221 bei m=0.01, schliesst sich gut an. In der folgenden
Tabelle befinden sich [959] die mittelst dieser resp. inter-
polierter Temperaturkoeffizienten auf 25° nach den Zahlen
von Herrn Kohlrausch 4 umgerechneten und die von uns bei
dieser Tempera tur durch fortgesetztes Verdiinnen gefun-
denen Werte fur das Leitungsvermogen von Silbernitrat.

TAB. 3

XX 108

XX 108

m

K.

L. u. N.

m

K.

L. u. N.

o-i

1018

1022

0-007

1178

1188

0-05

1071

1086

0-003

1211

1206

0-025

1128

1126

0-0015

1226

1221

0-015

1158

1153

0-0008

1234

1232

Der Parallelismus zwischen beiden Zahlenreihen ist befriedi-
gend. Fur die iibrigen Salze fanden wir folgende Werte,
wobei der Molekulargehalt m (g-Aequivalente pro Liter)
durch Bestimmung der (von eins wenig verschiedenen)
spezifischen Gewichte bei 18° aus der analytischen Bestim-
mung des Gehaltes in Gewichtsprozenten auf diese Tempera-

1 Zeitschr. 2, 563 (1888).

2 Unter "Leitvermogen" schlechthin sei hier "molekulares LeitungsvermSgen"

verstanden.
1 Wied. Annalen. 26, 223 (1885).

* Ibid. 195 (1885).

266

MORRIS LOEB

tur umgerechnet 1st. Die Korrektion wegen des Leitungs-
vermogens des zum Verdiinnen benutzten Wassers, welches
2.5X10"10 betrug, 1st in bekannter Weise angebracht worden.
Die -wegen Kontraktion der Losungen beim Verdiinnen
anzubringenden Korrekturen sind verschwindend.

TAB. 4

XX 108

771

AgC103

AgC104

Ag04SC2H5

Ag03SC10H7

Ag03SC8H5

0-025

1045

1109

_

0-015

1103

1139

—

882

846

0-007

1123

1160

905

893

874

0-003

1151

1182

930

926

897

0-0015

1160

1194

943

941

900

0-0008

1163

1200

949

951

906

TAB. 4 (FOKTSETZUNG)

m

AgO,SC,Hn

XX 108
Ag02C2H3

iAg2S206

iAg2SiFlfl

0-025

734

_

1253

995

0-015

762

—

1343

1020

0-007

791

897

1383

1054

0-003

813

926

1442

1081

0-0015

826

944

1474

1096

0-0008

836

949

1505

1100

[960] Die von Herrn Ostwald l an zahlreichen einbasischen
Natriumsalzen beobachtete Regelmassigkeit eines sehr nahe
gleichen Aktivitatskoeffizienten lasst sich auch leicht an dem
hier vorliegenden Material wiederfinden; die Quotienten des
Leitungsvermogens eines Salzes bei verschiedenem Gehalte
variieren bei den Silberverbindungen einbasischer Sauren
nur innerhalb der Grenzen, welche die Beobachtungsfehler
kaum iiberschreiten. Von dieser Thatsache soil Gebrauch
gemacht werden, um den Grenzwert des Leitungsvermogens

1 Ostwald, Zeitschr. 2, 847 (1888). '

KINETIK DER GELOSTEN KORPER 267

bei sehr grosser Verdiinnung zu erhalten, well bei der gering-
sten von uns untersuchten Konzentration 0.0008 die voll-
standige Dissoziation zwar sehr nahe, aber doch noch nicht
vollig erreicht 1st. Beachten wir namlich, dass Silbernitrat
nach den Messungen von Herrn Kohlrausch beim Gehalte
m = 0.0008 im Verhaltnis \jjSj in seine Jonen dissoziiert 1st,
so werden wir mit ziemlicher Genauigkeit die Grenzwerte von
X auch bei den ubrigen einbasischen Silbersalzen erhalten,
wenn wir die von uns bei m= 0.0008 gefundenen Werte um
0.75% erhohen.

In Tabelle 5 sind die Messungen verzeichnet, welche wir
iiber den Einfluss der Temperatur auf das Leitvermogen
ausgefiihrt haben; hier wurden an Stelle der platinierten
Platinplatten solche aus Silber als Elektroden im Wider-
standsgefass angewendet, wodurch ein sehr deutliches Ton-
minimum im Telephon erzielt wurde. X0, \i8, X28 bedeuten
die (direkt gemessenen) Leitvermogen bei den Temperaturen

\B

0°, 18° und28°; zieht man, von T— , 1 ab und dividiert durch 10,

A18

so erhalt man die Temperaturkoeffizienten zwischen 18° und
28°, welche mit den von Herrn Kohlrausch 1 mitgeteilten

X0
direkt vergleichbar sind. Ausserdem ist noch T— durch In-

terpolation berechnet.

TAB. 5

m

xl8

£

i

m

\L

fc

x25

AgN03

o-i

0-02
0-005

0 638
0-638
0-632

1-213
1-217
1-222

0-555
0-554
0-548

Ag03SC6H5
Ag02C2H3
AgO,SC,Hu

0-005
0-005
0-025

0-607
0-611
0-609

1-241
1-237
1-242

0-519
0-524
0-521

AgCIO,

0-005

0-626 1-222

0-542

0-006

0-606

1-246

0-517

AgC104

Ag03SC10H7

0-005
0-005

0-632
0 615

1-224
1-242

0-547
0-526

|Ag2S206

0-025
0-006

0-631
0-631

1-222
1-226

0-547
0-544

1 Kohlrausch, Wied. Annalen, 26, 223 (1885).

268 MORRIS LOEB

7. PRUFUNG DEE THEORETISCHEN BEZIEHUNG ZWISCHEN
LEITVERMOGEN UND UEBERFUHRUNGSZAHL

Hierzu bedarf man ausser der Kenntnis des Grenzwertes
des Leitungsvermb'gens bei unendlicher Verdiinnung, welche
wir uns soeben zu [961] verschaffen gesucht haben, noch der
Ueberfiihrungszahlen fiir ebenfalls sehr geringe Konzent-
rationen.

Nun hat, wie schon erwahnt, Herr Hittorf bei AgNO3
unter ra=0-3 n von dem Gehalte unabhangig, und wir haben
auch an anderen einbasischen Silbersalzen dies Resultat
bestatigt gefunden, so dass die von uns bei ra = 0-025-0-01
gefundenen Zahlen mit dem gesuchten Grenzwert identisch
sein diirften. Dieses Resultat leuchtet ohne weiteres ein, wenn
man, wie wir es auf Grund unserer Anschauungen annehmen
mlissen, eine Wanderung der inaktiven Molekeln fiir aus-
geschlossen halt, und bedenkt, dass bei einer Verdiinnung
von 0-01 auf 5550 Molekeln H2O erst ein Silberion kommt.
Dann wird sicherlich die Reibung, welche das Jon bei seiner
Fortbewegung erfahrt, von der im reinen Wasser nicht ver-
schieden sein. Dass dies selbst bei einer Konzentration von
m = 0 • 3 beim Silbernitrat noch der Fall ist, kann leicht daher
riihren, dass bei zunehmendem Salzgehalt die Reibung der
beiden Jonen in gleicher Weise (vermutlich verlangsamend)
beeinflusst wird.

Die Priifung des Gesetzes von Herrn Kohlrausch fiir den
Fall sehr grosser Verdiinnung lasst sich am einfachsten in
der Weise bewerkstelligen, dass man die Grenzwerte des
Leitvermogens mit (1-n), der Ueberfiihrungszahl des Rat-
ions, multipliziert; das Produkt, die molekulare Beweglich-
keit des Silberions, muss konstant sein.

KINETIK DER GELOSTEN KORPER 269

TAB. 6

XX108

(l-»)

\.(l-7l)108

XX 108

(1-n)

X. (1-71)108

AgN03
AgC103
AgC104
Ag04SC2H5

1242
1172
1208
956

0-477
0-499
0-486
0-615

592

585
587
588

Ag03SC10H7
Ag03SC8H5
AgOISC,H11
Ag02C2H3

958
913

842
956

0-614
0-653

0-707
0-624

588
596
595
597

Die Beweglichkeit des Ag ergiebt sich aus den verschiedenen
Salzen nahezu gleich; die Schwankungen um den Mittelwert,
591X10"8, bleiben innerhalb der Grenzen, welche durch
ungtinstige Haufung der Beobachtungsfehler gegeben sind.
Hierdurch erhalten die neuen Anschauungen iiber die Elek-
trolyse eine wiederholte Bestatigung.

Durch obigen Mittelwert, welcher fiir 25° giiltig ist, diirfte
die Beweglichkeit des Silberions, falls der den Messungen von
Herrn Kohlrausch entnommene Wert fur den Grenzwert des
Leitvermogens von Silbernitrat keinen in Betracht kommen-
den Fehler enthalt, bis auf wenige Tausendstel sicher gestellt
sein. Indem wir aus den bei 0° am salpetersauren und pseudo-
kumolsulfonsauren Silber ausgefiihrten Bestimmungen [962]

\>

von n (Tab. 2) und dem mittelst v~ aus Tab. 4 auf 0° umge-

A26

rechneten X das entsprechende Produkt bilden,
1242X0.461X0.548=314

842X0.727X0.517= 317

Mittel 315.5,

finden wir die Beweglichkeit des Silberions bei 0° und konnen
so durch Subtraktion dieser Zahl von den auf 0° umgerech-
neten Leitvermogen der ubrigen untersuchten Salze auch
zu den Geschwindigkeiten der ubrigen Jonen bei 0° gelangen.
Uebrigens liegt in der Uebereinstimmung der beiden obigen
Werte ein neuer Beweis fiir die Richtigkeit des zu priifenden
Gesetzes.

270

MORRIS LOEB

In der f olgenden Tabelle sind unter I die Jonengeschwind-
igkeiten bei 25°, unter II diese Grossen bei 0°, unter III die
Temperaturkoeffizienten a zwischen 25° und 0° nach der
Formel v=v^ (l+a(J— 25)) berechnet.

TAB. 7

08SC8Hn

03SC6H5

02C2H3

04S02H5

03SC10H7

C103

Ag

C104

N03

I 248

318

361

368

369

587

591

621

640

XlO-a

II 118

156

183

—

180

322

316

347

364

«

III 210

203

197

*~

198

181

186

177

175

XIO-*

Wie nahe die unter I aufgefiihrten Beweglichkeiten sich
den beobachteten Zahlen anschliessen, lehrt Tab. 8.

TAB. 8

X beob.

Xber.

Diff.

n beob.

n ber.

Diff.

AgO,SC,H11

842

839

- 3

0-293

0-295

+0-02

Ag03SC6H5

913

909

-4

0-347

0-350

+0-03

Ag02C2H3
Ag04SC2H5

956
956

952
959

-4
+ 3

0 376
0-385

0-379
0-384

+0-03

-o-oi

Ag03SC10H7
AgOlO,

958
1172

960

1178

+ 2
+ 6

0-386
0-501

0-384
0 499

-0-02
-0-02

AgC104

1208

1212

+ 4

0-514

0-512

-0-02

AgNOg

1242

1240

-2

0-523

0-524

+0-01

Ein Blick auf Tabelle 7, in welcher die Beweglichkeiten
nach ihrer Grosse geordnet sind, lasst eine auffallende Be-
ziehung des Temperaturkoeffizienten hierzu erkennen. Mit
zunehmender Beweglichkeit nimmt der Tem-
peraturkoeffizient ab. Es sei noch hinzugefiigt, dass
die entsprechenden Temperaturkoeffizienten der einwertigen
Jonen OH und H,1 welche durch besonders grosse Beweg-
lichkeit ausgezeichnet sind, sich an obige Reihenfolge eben-
falls anschliessen.

1 Nernst, Zeitschr. 2, 626.

KINETIK DER GELOSTEN KORPER 271

[963]

OH

H

I

187

350

xio-8

III

159

137

Xl(T4

Eine Folge dieser Gesetzmassigkeit ware, dass mit steigen-
der Temperatur die Ueberfiihrungszahlen dem Werte 0*5
zustreben, die Leitvermogen \m der verschiedenen Salze
sich einander nahern.1

Suchen wir auch aus den beiden untersuchten Salzen
zweibasischer Sauren die Beweglichkeit des Silbers zu be-
rechnen, indem wir aus Tabelle 4, Ao, extrapolieren, so er-
geben sich

ausAg2S2O6: 1540X0.394=0.607,
" Ag2SiFl6: 1120X0.534=0.598,

somit etwas grossere Zahlen, als bei den einwertigen Salzen.
Um nicht mit unseren Anschauungen, wonach dem Silberion,
gleichviel ob es durch Dissoziation aus einem ein- oder
mehrbasischen Salze entstanden ist, dieselbe Beweglichkeit
zuzuschreiben ist, in Widerspruch zu geraten, miissen wir
annehmen, dass die von uns bei dem Gehalte 0.025 resp.
0.028 gemessene Ueberfiihrungszahl sich noch mit abneh-
mender Konzentration andern muss. Leider war es in dieser
Arbeit, welche infolge der Abreise von Einem von uns zum
Abschluss gebracht werden musste, nicht moglich, diese
Forderung der Theorie zu priifen; doch sei noch kurz darauf
hingewiesen, dass nach der Dissociationshypothese eine Aen-
derung von n mit dem Gehalte bei so grossen Verdiinnungen,
bei denen die binaren Elektrolyte bereits eine konstante
Ueberfiihrungszahl aufweisen, fur die Verbindungen zwei-
basischer Sauren wahrscheinlich ist. Die Dissociationspro-
dukte von Ag2S2O6 z. B. sind Ag, AgS2O6 und S206; es geht

1 Vergl. auch Arrhenius, loc. cit. 45 (1884).

272 MORRIS LOEB

daraus hervor, dass selbst bei obigen Verdunnungen neben
den Jonen 4-Ag, +Ag, -S2O6, auf welche wir soeben Kohl-
rauschs Gesetz anzuwenden gesucht haben, noch solche in
nicht unbetrachtlicher Zahl von der Beschaffenheit +Ag,
-AgS2O6 existieren; mil einer fortschreitenden Dissoziation
dieser in jene ist dann natiirlich eine Aenderung der Ueber-
fiihrungszahl verkniipft. Es sind hier somit ahnliche Erwa-
gungen anzustellen wie die, durch welche Herr Hittorf bereits
vor 29 Jahren1 gelegentlich der Beobachtung anomaler
Ueberfiihrungszahlen bei Jodkadmium die Schwierigkeiten,
welche hierdurch seiner Theorie erwuchsen, so gliicklich
beseitigt hat.

1 Hittorf, Pogg. Annalen, 106, 546 (1859).

[106] THE RATES OF TRANSFERENCE AND

THE CONDUCTING POWER OF CERTAIN

SILVER SALTS1

1. INTRODUCTION

WHENEVER a current of electricity is passed through a
conductor of the second class, under such conditions that the
composition of the solution is not changed, as when a current
passes between electrodes of the same metal in a solution of
a salt of that metal, curious changes of concentration appear.
This was noticed by many scientists, but it was reserved for
Hittorf to investigate these changes quantitatively and to
advance a plausible and exhaustive hypothesis of their causes.
His work constitutes one of the classics in physics; but as it
is not, perhaps, so generally known to chemists, a short ex-
planation of his hypothesis may be a not inappropriate in-
troduction to our paper. Taking the example already cited,
it is, of course, a familiar principle, that in a given interval
the same amount of metal is dissolved from the positive elec-
trode as is deposited upon the negative electrode. If we were
to assume that the ions of the electrolyte were incapable of
moving independently of each other, the changes in concen-
tration at the two electrodes could only be counterbalanced
by the slow process of diffusion, and we should find a deficit
in the liquid around the negative electrode corresponding
to the amount of metal deposited upon the latter, while all
the metal yielded up by the positive electrode would be found

1 In collaboration with Walther Nernst. Reprinted from American Chemical
Journal, 11, 106 (1889). This paper is an abbreviated translation of the fore-
going monograph, made by Dr. Loeb. [EDITOR.] ,

274 MORRIS LOEB

in its immediate surroundings. This is, of course, an unten-
able assumption. Supposing, on the other hand, that only the
negative ions were immovable, while the positive ones could
travel across the liquid as fast as required to supply the places
of those disappearing upon the negative electrode : the liquid
would be homogeneous at all moments, and there would be
no concentration nor dilution around the electrodes. We can-
not, however, assume that the negative ions are immovable,
everything showing that they move toward the cathode
just as well as the positive ones do toward the anode. If both
move [107] with equal rapidity, as was tacitly assumed be-
fore Hittorf , a little reflection will show that the liquid about
the cathode will lose just half as much metal as is deposited
upon the electrode, while half the metal given up by the
anode to the surrounding liquid will have been transferred
toward the cathode. Hittorf 's laborious analyses proved that
none of these three possibilities was fulfilled. The relation
between the changes in concentration and the amount of
metal transferred from one electrode to the other proved
conclusively that the two classes of ions did not move with
equal rapidity; and he showed how this ratio provided a
measurement of the share of each class in the total movement.
For any salt, [the reciprocal of] the ratio of the weight of the
metal deposited to the amount of metal lost by the fluid
around the cathode (or its equivalent, the amount gained
by that around the anode) represents the share of the nega-
tive ion, the anion, in the total movement.

Hittorf has had few followers in these investigations,1 as
the difficulties of experiment were discouraging. Analytical
accuracy demanded the use of concentrated solutions, or of

1 The following list includes all the literature; Hittorf, Pogg. Annalen, 89, 177,
98, 1, 103, 1, 106, 337; G. Wiedemann, Ibid. 99, 177; Weiske, Ibid. 103, 466;
Kuschel, Wied. Annalen, 13, 289; Kirmis, Ibid. 48, 503; Lenz, M6m.Ac. St. Ptters-
bourg, 30, 1882.

KINETICS OF CERTAIN SILVER SALTS 275

bulky and cumbrous apparatus, while it was especially de-
sirable to study dilute solutions, and to use apparatus which
was not subject to such disturbances as variations of tempera-
ture, osmose, and the jars unavoidable during mechanical
handling produce. Considerations which will be explained
later led us to attempt the acquisition of fresh material, es-
pecially with reference to highly dilute solutions. We found
that we could do this by studying certain silver salts, mainly
organic; and we were led to this choice firstly because silver
is the only monovalent metal which furnishes a satisfactory
electrode — a matter of some moment for our subsequent
work; secondly, because its salts are readily obtained in the
needful state of purity; finally, because Volhard's beautiful
method of titration l enabled us to perform the necessary
analyses with great ease and extreme nicety. We also
availed ourselves of the opportunity for studying the effects
of temperature and concentration upon the velocity of the
ions of these salts, because one of us 2 has recently shown how
important a part is played by these factors in the kinetics of
solutions.

[108] 2. APPARATUS FOR THE DETERMINATION OF THE
RATE OF TRANSFERENCE

In this apparatus we wished to avoid the use of membra-
nous diaphragms, and to minimize the internal resistance,
necessarily large by reason of our very dilute solutions, so
as to keep the necessary duration of an experiment within
reasonable limits. After various failures we finally hit upon
a form whose simplicity is likely to recommend it in similar
cases. As shown in the accompanying drawing, it is seen to
resemble the Gay-Lussac burette, but with the addition of
a short side-tube of the same bore as the main tube. This side-

1 Volhard, Annalen, 190, 1. 2 Nernst, Zeitschr. 2, 613.

276

MORRIS LOEB

tube ends in a bulb, and upon this is set a narrower vertical
tube, through which the negative electrode — a cylindrical

roll of silver foil fastened to a sil-
ver wire — can be let down into
the bulb. This works as a sort
of pocket, by which masses of the
spongy precipitated silver that
may become detached from the
electrode are prevented from stir-
ring up the body of the solution.
The anode consists of a silver wire
rolled into a spiral at the lower
end. It is introduced through A,
and reaches to the bottom of the
main tube. In order that the cur-
rent may enter the liquid only
at the spiral, the straight part of
the wire is covered with a capillary of very thin glass, which
can be closed around the wire by fusion, in spite of the
difference in their coefficients of expansion. The openings
A and B are closed with corks that are traversed by short
glass tubes. Of these, the tube at A allows free passage to the
wire of the electrode. The wall of the tube at B is pierced by
a platinum wire, which serves to suspend the cathode and to
connect it with the conductor of the battery. Thus A can be
closed by the compression of a bit of rubber tubing drawn
over the wire and glass tube, or air can be sucked or blown
through a rubber tube connected with B, without disturb-
ing the electrodes.

[109] In experimenting, such an apparatus would first be
weighed with its electrodes and stoppers, but without the
rubber tubing. The latter was hereupon put in position, A
was closed with a pinch-cock as just indicated, and air was

KINETICS OF CERTAIN SILVER SALTS 277

drawn out at B while the nozzle C was dipping under the sur-
face of the solution to be used. By this process, the main- and
side-tubes were filled up to the level of the top of the latter;
the sizes of apparatus we employed contained 40 and 60 cc.
respectively. The nozzle was now likewise closed with a rubber
cap, and the whole apparatus suspended in one of Profes-
sor Ostwald's thermostatic water-baths,1 in such a fashion
that the nozzle protruded over the rim, while the liquid
was entirely within the water-bath. After it had acquired
the temperature of the bath, the circuit was closed. As soon
as the electrolysis was concluded, the nozzle was opened and
suitable portions of the liquid were filled into tared vessels,
by blowing steadily through B. These portions were weighed
and analyzed. The portion remaining in the apparatus was
estimated by the latter's gain in weight, and likewise analyzed.
Provided there has been no mixing through diffusion and con-
vection during the electrolysis, the first portion taken from
the apparatus, if the liquid is properly divided, will consist
of the stratum around the anode, which has become more
concentrated, and of a sufficient quantity of the unaltered
middle layers to insure a rinsing of the adhering parts of the
lowest stratum. The succeeding portions, being composed
wholly of the middle layers, must show an unaltered compo-
sition, while what is left in the apparatus includes the diluter
strata about the cathode. To prove the reliability of our ex-
periment, we must find in the first place that the middle
layers had remained unchanged, and secondly, that the
gain of the lowest layer exactly counterbalanced the loss of
the highest, for the mean composition of the whole liquid
undergoes no change. After finding that the first condition
was invariably fulfilled, we saved time by giving up the sep-
arate examination of the middle layers, and divided the whole

1 As described recently by Professor Ostwald, Zeitschr. 2, 565.

278 MORRIS LOEB

liquid into two nearly equal portions. It frequently happened
that, during the electrolysis, the electrolyzed silver would
grow out from the bulb along the wall of the horizontal
tube. In such cases the circuit was broken before the
silver had reached the main tube; otherwise, [110] we dis-
connected whenever we estimated that a sufficient change
of concentration had taken place to give the most reliable
results.

The analyses were performed, as already intimated, by
titration with a solution of ammonic sulphocyanate, the
standard of which (about j^ normal) was ascertained by fre-
quent comparison with an argentic nitrate solution of known
strength, occasional gravimetric determinations of which
gave absolutely constant results. We claim for the titrations
an error well within ^ cc. (= 0.038 milligrams Ag), each
end-reaction being observed twice, as 1 cc. of a ^ normal
solution of argentic nitrate was added from a pipette, after
the first appearance of the characteristic tint, and the titra-
tion repeated.

The ratio we are seeking to determine requires, besides the
data of the change in concentration, the weight of the silver
which has been actually deposited upon the cathode, in the
same interval of time. This would most naturally be deter-
mined by a silver voltameter placed in the same circuit with
the apparatus. But as the examination of dilute solutions
often necessitated the deposit of less than 20 milligrams in
all, and the silver is deposited in such a form upon the vol-
tameter that it is difficult to weigh it without a slight loss, we
found it to be more advantageous to determine the quantity
of electricity which traversed the apparatus by galvanometric
measurement. A resistance-box was introduced into the cir-
cuit for this purpose (see figure), to the extremities of which
a second circuit was connected, containing a Clark's cell and

KINETICS OF CERTAIN SILVER SALTS 279

a galvanometer with direct reading. The Clark's cell being
introduced in the proper direction, it is well known that a
suitable resistance R may be introduced by means of the box,
which will put the galvanometer at rest at the 0 point; when
this is effected, we have for the electrical intensity of the main

E

current i = —>E denoting the electromotive force of the stand-
R

ard Clark's cell. As the intensity of the current changed but
little and very gradually during the four or five hours which
were usually occupied by an electrolysis, we were satisfied
with making this measurement, which required but a few
seconds' attention, every ten minutes. The total amount
of electricity could then be integrated with sufficient cer-
tainty.

Special experiments showed that, when resistance-box and
[111] Clark's cell were at a temperature of 18° C., the quan-
tity / of precipitated silver could be found by the formula,

/ =^92.69,

where T represents the duration of the electrolysis in minutes,
while r denotes the resistance which would have been neces-
sary to keep the galvanometer at 0, provided that amount
of electricity which actually passed through the apparatus
had done so in a current which remained constant throughout
this interval. Whenever the resistance-box and the cell were
at any other temperature, t, the above expression must be
multiplied with the factor 1-0.0012 (Z-18). This coefficient
of temperature, 0.0012, is derived from that of the cell,
-0.0008, and that of the box, +0.0004.

Our battery consisted of 38 Leclanche cells, with a com-
bined electromotive force of about 40 volts and an internal
resistance of about 120 ohms. It furnished a current which

280 MORRIS LOEB

remained practically constant for many hours, when enclosed
in a circuit of 5000-10,000 ohms resistance. It also had the
advantage of being always ready for use.

3. PREPARATION OF THE SILVER SOLUTIONS

The solutions of argentic nitrate were prepared from the
crystallized salt. Those of the chlorate, perchlorate, ethyl-
sulphonate, naphthalene-sulphonate, benzene-sulphonate,
pseudo-cumene-sulphonate and acetate, were made by neu-
tralizing known amounts of these acids with moist argentic
oxide, passing the solution through an asbestos filter, and
diluting to a suitable volume. Argentic dithionate (Ag2S2O6)
was obtained by the reaction of exactly equivalent quantities
of baric dithionate and argentic sulphate. To make ar-
gentic fluosilicate, a solution of hydrofluosilicic acid was
saturated with argentic oxide; dilute baric hydrate solution
was then added cautiously, until the brown color of argentic
oxide commenced to appear in the precipitate of baric fluo-
silicate. The neutral solution was then filtered and diluted.

4. DESCRIPTION OF A DETERMINATION IN DETAIL

The description of this determination, made with a solution
of argentic nitrate which was about ^ normal, will best
illustrate our method of experiment and calculation. The
electrolysis was [112] conducted at a temperature of 26°, and
the solution thereupon divided into four portions, which are
numbered in the following table in the order in which they
were taken out; consequently, No. 1 represents the lowest
stratum in the apparatus. Column I contains the weights of
these portions; II, the amount of silver found in each; III,
the amount each portion would have contained if no change
had occurred, estimated from the fact that 1 gram of the
solution originally contained 1.139 milligram of silver.

KINETICS OF CERTAIN SILVER SALTS 281

TABLE I

Portion
1
2
3
4

I

20-09 grams
5-27
5-33
27-12

II

39-66millig.
5-96
6 04
14-14

III

22-88millig.
6-00
6-07
30-89

Diff.

+16-78millig.
- 0-04
- 0-03
-16-75

57-81 65-80

It will be seen that the strength of two middle portions has
remained constant, within the errors of determination; we
also find a close agreement in the second test, which demands
that the mean concentration shall remain unchanged; the
value 65.80/57.81 = 1.138, scarcely different from the original
strength 1.139.

The measurement of the electrical current as described
above informed us that a quantity of electricity equivalent
to the precipitation of 32.10 mg. of silver had passed through
the apparatus; while a silver- voltameter, placed in the circuit
for our better assurance, contained 32.2 mg.; the former value
was accepted as the more trustworthy.

Following Hittorf,1 we based these calculations upon our
data: The solution at the anode (1) received from the latter
32.1 mg. Ag, and the uppermost layer (4) gave up the same
amount to the cathode. Owing to the changes in concentra-
tion, the values in the above table are not absolutely correct,
since 1 gram of solution does not always contain the same
weight of water, as had been provisionally assumed. But the
necessary correction is small and readily made. Let v be
the ratio of the molecular weights of silver and the salt in
question; in this special case v = ^ = 1.57. Let a represent
the amount of silver contained in 1 gram of [113] unaltered
solution, being consequently dissolved in (I—av) grams of
water. If, after electrolysis, q grams of the solution about
one electrode are found to contain b grams of silver, the

1 Hittorf, Pogg. Annalen, 98, 19.

282 MORRIS LOEB

a(q-bv) b-aq

gain or loss will be represented by ±6 — =± .

l-av I-av

As b-aq is the value given in the column of differences, the

factor represents the necessary correction. Conse-

1— av

quently, after completing the deficit of portion 4 by the
addition of the small deficits in 2 and 3, we have for the
rate of transference of the negative ion,

16.78 , 16.82

1.0017 and - -1.0017, or a mean value of 0.524.

32.10 32.10

As already stated, the determination was usually simplified
by dividing the liquid into two portions instead of four.

In this experiment there was a second apparatus placed in
series in the circuit; hence the mean intensity of the current
was only 0.0012 ampere, and the electrolysis lasted seven
hours. We frequently saved time and used our battery to
better advantage by performing two simultaneous elec-
trolyses in parallel circuits, each of which must, of course,
contain its own resistance-box; by means of a properly
constructed switch, we could apply the measuring circuit to
either box at will, thus securing the measurement of both
electrolyses with the same galvanometer and element. We
may also state here that the last was frequently compared
with another cell of the same construction and was always
found to be exactly equivalent to it in electro-motive force,
a proof that it did not vary during the course of our
experiments.

5. RATES OF TRANSFERENCE OF THE NEGATIVE ION

Hereafter t implies the temperature during electrolysis;
m the molecular concentration (gram-molecules per liter);
/i the milligrams of silver precipitated on the cathode accord-

KINETICS OF CERTAIN SILVER SALTS 283

ing to galvanometric measurement ;/2 the same value accord-
ing to the voltameter whenever it was used; n the rate of
transference.

Argentic Nitrate

1) £ = 20° m = 0-1043 .ft = 83-5 /2 = 83'6 7i = 0'528

2) £ = 26° m = 0-0521 /t = 76'7 w = 0'524

3) £ = 26° ra = 0-0250 /1==48'0 71 = 0.5223
4)*= 0° m = 0-0250 /1==48-0 7i = 0'5383
5) £ = 26° 771 = 0-0105 ^ = 32-10 /2 = 32'2 ft, = 0'524
6)2 = 26° ra = 0'0105 ^ = 32-10 /2 = 32'2 7i = 0'524

[114] In 3) and 4) and in 5) and 6) both pieces of apparatus were in the same cir-
cuit.

Argentic Chlorate

1)^ = 24-8° 771 = 0-0245 /.= 39-88 /2=39'5 7i = 0'503

2) £ = 24-8° w = 0-0245 ^ = 51-72 7i = 0'499

Argentic Perchlorate

1) £ = 24-8° m = 0-0247 .ft = 39- 88 /2 = 39"5 7i = 0'515

2)^ = 24-8° m = 0-0247 ^ = 51-72 7i = 0'512

In studying these two solutions, 1) and 1) and 2) and 2) were in the same cir-
cuits.

Argentic Ethyl-sulphonate

1)^ = 24-8° m = 0-0243 ,ft = 58-30 7i = 0'385

2)^ = 24-8° rri = 0-0243 ^ = 48-47 /2=48'34 n = 0'389

3) £ = 25° m = 0-00606 ^ = 18-10 7i = 0'384

Argentic Benzene-sulphonate

2)^ = 24-7° m=0-0250 /J = 17-85 7i = 0'351
2) of the former and 1) of the latter solution were electrolyzed in series.

Argentic Pseudocumene-sulphonate

1)^ = 24-2° 771 = 00235 /,=61'62 n = 0'293

2)^ = 29-2° m = 0-02216 /,=38'24 7i = 0'2947

3)^ = 0° 771 = 0-02216 .ft = 38-24 n = 0'2732

4)^ = 0° 771 = 0-02216 .ft = 42'79 7i = 0'2731

2) and 3) were electrolyzed in series.

Argentic Naphthalene-sulphonate

1) £ = 29-2° 771 = 0-01292 /t = 33'95 n-0'390

2)^ = 25-0° m = 0-0250 /1 = 39'75 /2 = 39'5 n = 0'386

284 MORRIS LOEB

Argentic Acetate

In examining this salt, we were surprised to find that the
middle layers of the solution did not remain unchanged, and
that the mean concentration after electrolysis did not agree
with the [115] original standard. This irregularity is probably
due to the slight solubility of the salt, since it can easily
happen that the solution about the anode becoming over-con-
centrated, some of the salt crystallizes out and vitiates the
result. In fact, we did succeed in obtaining reliable values
when we had recourse to a highly dilute solution.

1) * = 25° 77i = 0-00972 /t = 20-80 7i = 0'375

2) * = 24° m = 0-00972 /1 = 23'99 tt = 0'377

Argentic Dithionate

1) f = 24-8° 771 = 0-0246 ^ = 33-40 n = 0'604

2) * = 29'2° w = 0-0246 /x = 46-70 n = 0'604
8) t= 0° m = 0-0246 /! = 46-70 7i = 0'605

4) £ = 24 2° m = 0-0246 /1 = 48-85 ft = 0'606

5) t= 0° 771 = 0-0246 ^ = 45-80 n = 0-603

2) and 3) were electrolyzed in series.

Argentic Fluosilicate

1) £ = 22 -2° m = 0-02815 ^ = 60-28 n = 0'647

2) * = 22-2 m = 0-02815 ^ = 37-44 n = 0'647

In Table II we summarize these values of n, with the
corresponding temperatures and concentrations.

TABLE II

Argentic n t m

Nitrate 0'523 25° ) ft-1 O.ft1

0-539 0° ]

Chlorate 0'505 25° 0-0245

Perchlorate 0"514 25° 0 0247

Ethyl-sulphonate . . . . 0'385 25° 0-0243-0-0061

Naphthalene-sulphonate . .0-390 30° In- no™ A.AIQ

0-386 25° /° Ux}5U

Pseudocumene-sulphonate . 0'293 25° \o-09q

0-273 0° /°023

Benzene-sulphonate . . . 0'347 25° 0'025

Acetate 0"376 25° 0-097

Dithionate 0-604 25°

0-604 0°

Fluosilicate . .0'466 22° 0'0282

0-604 Oo }°0346

KINETICS OF CERTAIN SILVER SALTS 285

Argentic nitrate has been carefully studied by Hittorf,1
who found that between the concentrations 0.3 and 0.024
the rate of transference does not vary, the mean value being
0.526 at 19°. We came to the same conclusions for variations
of concentration [116] from 0.1 to 0.01, and we found a value
which, when reduced to the same temperature, very nearly
agreed with his, 0.527 at 19°. The acetate result given
above also agrees well with Hittorf 's (0.373 where 2 = 15° and
m= 0.05).

6. CONDUCTING POWER OF THE SILVER SALTS AND ITS RELA-
TION TO THE RATE OF TRANSFERENCE

It will be noted that the rate of transference is a value
varying with the compound, since it merely expresses the
share of the one ion in the total movement. If u is the ac-
tual velocity of the positive ion and v that of the anion,

n= - ; and the rate of the positive ion, l-n= -- . Kohl-

u+v u+v

rausch,2 as is well known, has propounded the simple hy-
pothesis that the conducting power of a molecule of an
electrolyte is represented by the sum of the velocities of

itsions>

His experiments, however, did not seem to give the re-
quisite support to this theory, some salts giving approximate
results, but those of weak bases and acids giving utterly dis-
cordant figures. The difficulty is removed if we assume that
the conduction is not performed by all the molecules of the
electrolyte, but only by those whose ions are actually in
independent motion. This is Arrhenius's principle of conduc-
tive activity.3 Kohlrausch's values for molecular conduc-

1 Pogg. Annalen, 89, 199.

* FT. Kohlrausch, Wied. Annalen, 6, 1.

1 S. 'Arrhenius, Sur la conductibttiti, etc., Stockholm, 1884.

286 MORRIS LOEB

tivity are a function of the total number of molecules of the
electrolyte between the electrodes; according to Arrhenius,
the coefficient of activity, i.e., the proportion of molecules
actually engaged in conduction, not only varies for different
compounds, but also increases for any one compound with
its dilution, and approaches unity for extreme dilutions. It is
only in this limiting case that Kohlrausch's equation becomes
absolutely true; this is the view that Kohlrausch himself
had expressed with regard to his law, whose accuracy, he said,
could only be tested by experiments with highly dilute solu-
tions. Ostwald's examination of the conducting power of
highly attenuated solutions of a very large number of electro-
lytes l has afforded very valuable support to these recent
views.

Since, however, the quantities u and v are so closely con-
nected [117] with the rate of transference of the ions, a study
of the latter in dilute solutions must afford powerful means
of testing the truth of Kohlrausch's law with Arrhenius's
emendations. This was the chief motive of our work, and we
must now, therefore, proceed to compare the values which we
have given in section 5 with the conducting power of the same
salts. Accordingly, the necessary measurements of conduc-
tion were made by one of us (W. N.), by Kohlrausch's method
which with various valuable modifications has been described
by Professor Ostwald.2 The values which we present are
scaled upon the conducting power of mercury as unity, and
the calculations are based upon Kohlrausch's determination
of the molecular conductivity of argentic nitrate.3

The following table gives the conducting power of the dif-

1 Zeitschr. 1, 61 and 97. * Ibid. 2, 563.

3 As Kohlrausch worked at 18°, while the present determinations were made at
25°, the coefficients of temperature were determined by special experiments for va-
rious dilutions of AgNOa. For the details of these results we must refer to the Ger-
man version of our paper.

TABLE III

771

X X 108 at 25'

AgN03

AgC103

AgC104

0-025

1126

1045

1109

0-015

1153

1103

1139

0-007

1188

1123

1160

0 003

1206

1151

1182

0-0015

1221

1160

1194

0-0008

1233

1163

1200

KINETICS OF CERTAIN SILVER SALTS 287

ferent silver salts. The molecular concentration (gram-mole-
cules in the liter) m, was calculated from the percentage com-
position as found by analysis, and the specific gravity de-
termined at 18°, although this barely differed from that of
water. There was no appreciable contraction when additional
water was added for dilution; but a proper correction was
made for the conduction by the water itself, which was found
to be 2.5 X10"10.

Ag(C2H5S04) Ag(C8H6SOs)

846

905 874
930 897
943 900
949 906

m X X 108 at 25°

Ag(C8HnS03) Ag(C10H7S03) AgC2H3O3 £Ag2S2Ofl £Ag2SiFl,

0-025 734 ... ... 1253 995

0-015 762 882 ... 1343 1020

0 007 791 893 897 1383 1054

0-003 813 926 926 1442 1081

0-0015 826 941 944 1474 1096

0-0008 836 951 949 1505 1100

[118] Ostwald has found 1 that the sodium salts of numerous
monobasic acids have almost identically progressing coeffi-
cients of activity; the same regularity may be observed in the
present series. The ratios of the conductivity of a salt in va-
rious states of dilution agree, for the silver salts of the mono-
basic acids, within limits that scarcely transcend the probable
errors of observation. We shall utilize this fact in finding
the limit of the conductivity for extreme dilution; for, at
the concentration 0.0008, the dissociation of the molecules
is not yet complete, although very nearly so. If we re-
member that, according to Kohlrausch's measurements, when

1 Ostwald, Zeitschr. 2, 847.

288 MORRIS LOEB

m = 0.0008, ^ of the molecules of argentic nitrate are disso-
ciated, we can fairly assume that the limiting values of X for
the other silver salts may be obtained by raising by 0.75 per
cent the values found for m= 0.0008.

Table IV summarizes the measurements made to deter-
mine the effect of temperature upon conducting power; in
these the platinum electrodes usually employed were replaced
by silver ones, which gave very sharp readings. The mea-
sured conductivities at 0°, 18°, and 28° are denoted by XQ, X18
and X28 respectively; to obtain the coefficient of temperature

Y^ must be diminished by 1 and divided by 10; ^- was

A18 A25

calculated from such an interpolated value of X25-

TABLE IV

AgNOs ....... 0-1 0-638 1-213 0-555

0-02 0-638 1-217 0'554

0-005 0-632 1-222 0'548

AgClOg ....... 0-005 0-626 1-222 0-542

'AgClO4 ....... 0-005 0-632 1*224 0-547

AgCIOH7SO3 ...... 0-005 0-615 1'242 0-526

AgC,H5SO3 ...... 0-005 0-607 1-241 0'519

AgC2H302 ...... 0-005 0-611 1-237 0-524

AgC9HuSO3 ...... 0-025 0-609 1-242 0'521

0-006 0-606 1-246 0'517

£Ag2S2Oe ....... 0-025 0-631 1-222 0'547

0-006 0-631 1-226 0'544

[119] 7. TEST OF THE LAW OF KOHLRAUSCH FOR
EXTREME DILUTIONS

For this purpose we need, besides the limiting values for
conduction, which we have just shown to be attainable, the
limiting values for the rate of transference, likewise for ex-
treme dilution.

At the close of section 5 we noted that Hittorf found the
value of n to be independent of the state of dilution where

KINETICS OF CERTAIN SILVER SALTS 289

m <C 0.3 in the case of AgNO3, and that we confirmed his
result by our own experiments on this and other salts.
Consequently the values found for this rate, whenever
m = 0.025—0.01, can be assumed to hold good for infinite
dilutions. The reason becomes apparent when, considering
the inactive molecules as stationary, we remember that a
molecular concentration 0.01 means a proportion of one sil-
ver ion to 5550 molecules of H2O. The resistance which
such an ion would encounter cannot differ from that of pure
water.

The testing of Kohlrausch's law can now be readily ac-
complished by multiplying the limiting value of conductivity
into (1— ft), the rate of transference of the positive ion; the
product, which represents the molecular velocity of the silver
ion, must remain constant for all the monobasic salts.

TABLE V
XX108 (1-rc) X(l-n)108

AgNO3 1242 0-477 592

AgCIO, 1172 0-499 585

AgC104 1208 0-486 587

AgC2H5SO4 956 0-615 588

AgC10H7SO3 958 0-614 588

AgC6H5SO3 913 0-653 596

AgC9HuS03 842 0.707 595

AgC2H3O2 956 0-624 597

The velocity of Ag as found in these salts proves to be
nearly constant: the deviations from the average 591 X108
are within the limits of the probable errors of observation,
especially as the latter have a cumulative effect. We con-
sider this an additional confirmation of the recent electrolytic
hypotheses.

This average, which applies for 25°, may be considered the
true value for the velocity of the Ag ion, within a few thou-
sandths, provided Kohlrausch's determination of the limit of
conduction for argentic nitrate contains no important error.

290 MORRIS LOEB

We can now calculate the ion's velocity at 0°, from the values
of n at that temperature for argentic nitrate and pseudo-
cumol-sulphonate (Table II), and [120] the values of X re-
duced from Table III by the ratio ^~ (Table IV).

A25

1242 X 0.461 X 0.548 = 314

842 X 0.727 X 0.517 = 317 Mean = 315.5.

We again call attention to the smallness of the deviation.
Now, since \=u+v, we can obtain the velocities of all our
negative ions, by subtracting the velocity of the silver from
the respective conducting powers. In Table VI we find on the
first line the velocities at 25°; on the second, those at 0°; on
the third, the coefficient of temperature between 25° and 0°,
as calculated from the formula v = v^[l+a(t-^5)], a being
the coefficient: all the values must be multiplied by the
factor given in the final column.

x io-8

X IO-8

x 10-*

X 10-8
X 10-8

x 10-*

The close agreement of the velocities shown in line I with
the observations of the rates of transfer and of the conduc-
tion, is proved by the fact that the calculated and observed
values agree within one half per cent in all cases. A glance at
Table VI, in which the velocities are arranged according to
magnitude, will bring out a striking relation of the coefficients
of temperature. The coefficient of temperature decreases when
the velocity increases. We may add that the coefficients of
temperature for the monovalent ions OH and H, which

TABLE VI

C8HnS03

CflH5S03

C2H302.

C2H5S04

I.

248

318

361

368

II.

118

156

183

III.

210

203

197

...

C10H7S03

C103

Ag

C104

N03

I.

369

587

591

621

640

II.

180

322

316

347

364

III.

198

181

186

177

175

KINETICS OF CERTAIN SILVER SALTS 291

have an exceptionally great velocity, can be added to this

series.1

OH H

I. 187 350 X 10-'

III. 159 137 X 10-4

A result of this regularity would be that, as the tempera-
ture rises, the rates of transference would all approach the
value 0.5, and the conducting powers Xoo of all salts would
approach equality.2

If we attempt to calculate the velocity of the silver ion
from [121] the salts of the two dibasic acids which we have
studied, we obtain from

Ag2S2O6: 1540 X 0-394 = 0-607
Ag2SiP6: 1120 X 0'534 = 0'598

These values are somewhat greater than those found be-
fore. To avoid a conflict with the necessary assumption that
the free ion of silver must have the same velocity, no matter
whether it has been liberated from a mono- or dibasic acid
ion, we must admit that the rates of transfer in these two
salts, which were measured at a concentration 0.025 and 0.028
respectively, must change on further dilution. As our inves-
tigation was brought to a close by the departure of one of us
from Leipzig, we were unable to set this question at rest; we
note in passing, however, that the dissociation hypothesis
makes it probable that the compounds of multivalent radicals
are still undergoing changes at dilutions in which mono-
basic compounds show a constant rate of transference. The
dissociation products for Ag2S2O6, for instance, are Ag,
AgS2O6 and S2O6; consequently in such dilutions as 0.025
there may exist, besides the ions +Ag, +Ag, -S2O6, upon
which we based our calculations, a considerable set of ions
+Ag, -AgS2O6; if these decompose on further dilution, the

1 Nernst, Zeitschr. 2, 626. 2 Compare Arrhenius, loc. cit., p. 45.

292 MORRIS LOEB

rate of transference must continue to change. We have here
considerations similar to those which Hittorf used so skill-
fully nearly thirty years ago,1 in obviating the difficulties
which the abnormal behavior of cadmic iodide threatened to
cast in the way of his theory.

1 Hittorf, Pogg. Annalen, 106, 546 (1859).

[300] THE USE OF THE GOOCH CRUCIBLE AS
A SILVER VOLTAMETER1

FOR the exact measurement of electric currents, no method
is more convenient and more free from objections than the
determination of the amount of silver deposited from a neutral
solution of a silver salt. The sole source of error, especially
where weak currents are concerned, arises from the imperfect
adhesion of the silver upon the cathode. The latter is gener-
ally a platinum crucible, and the silver, except for densities
of current not always attainable, is deposited in minute
scales and needles, instead of forming a coherent coating.
In the subsequent washing and decantations, those par-
ticles are readily detached and carried away, and a loss is
occasioned which becomes very appreciable when the total
deposit does not exceed a few centigrams. A Gooch crucible,
with asbestos felting over the holes, would be a far better
form of cathode, if it would only hold the solution during
electrolysis without leaking. I have attained this very satis-
factorily, by replacing the ordinary platinum cap with a glass
siphon of the shape indicated in Fig. 1.

. 1. FIG. 2.

1 Reprinted from Journal of the American Chemical Society, 12, 300 (1890).

294 MORRIS LOEB

The crucible is made on a rather taller and narrower pattern
than is usual, and it fits quite snugly into the upper portion
of the cup [301] of the siphon. The two are united by a bit of
rubber drawn over the junction; the rubber should be freed
from sulphur, although there is no real danger of contact with
the silver solution.

The apparatus is filled with the silver nitrate solution, so
that the top of the siphon is not quite reached and is set upon
the stand, Fig. 2. After the completion of the electrolysis,
adding a little liquid causes the siphon to act and to drain
off every drop of nitrate solution, without in any way dis-
turbing the deposit; the lixiviation with hot water is equally
expeditious, and the crucible can then be detached from the
siphon, dried and weighed.

The stand for this voltameter is seen in Fig. 2. The crucible
is hung in a brass block, the conical hole in which fits exactly
around its upper third; to this block the negative wire of the
circuit is to be attached.

The positive wire is connected with a long horizontal cone,
which is isolated from the cast-iron base, and from which the
silver cone that forms the anode is suspended within the
crucible by a silver wire.

[145] IS CHEMICAL ACTION AFFECTED BY
MAGNETISM? 1

THE close relationship between electricity and chemical
affinity on the one hand, and that between electricity and
magnetism on the other, have naturally raised the question
whether any relation can be traced between affinity and mag-
netism.

This question was the subject of numerous investigations
during the entire first half of this century,2 but appears to
have dropped out of sight, until Professor Remsen,3 in 1882,
again attracted attention to it by the interesting observation
that, from a solution of the sulphate, copper is unequally de-
posited upon the armature of a horse-shoe magnet. Other
experiments by Messrs. Nichols and Franklin,4 and Messrs.
Rowland and Bell,5 have also borne relation to this question.
I have nevertheless ventured to approach the subject from a
new side, with the conviction that all of these investigations
introduce phenomena which tend to obscure the point of
issue, i.e., the effect of magnetism upon the chemical reaction
itself. This will be made clear by an analysis of the principles
upon which these investigations have been conducted; they
can be divided into four categories.

The earliest experiments regarded the rusting of bar mag-
nets; and the most trustworthy observers appear to invali-
date the assertion of a few, that magnetized iron differs from

Reprinted from American Chemical Journal, 13, 145 (1891).

For full literature see E. Wartmann, Philosophical Magazine, 30, 266.

American Chemical Journal, 3, 137.

American Journal of Science, 34, 419; 35, 290.

Philosophical Magazine, 34, 419; 35, 105.

296 MORRIS LOEB

the non-magnetized [146] metal in this respect, or that the
north and south poles show dissimilar behavior. The experi-
ments were naturally crude, and a positive result, were it ad-
mitted, would obviously have been due to a polarized ar-
rangement of the molecules, rather than to variations in
chemical affinity.

Next came the crystallization of salts or metals from a so-
lution, within and without a magnetic field. Quite a number
of observers appear to have found that the direction of growth,
either of the crystals themselves or of the clusters which they
form, can be affected by the presence of a magnetic field,
even though the substance be a diamagnetic. But what is
there in this that involves a modification of chemical action?
The quantity of deposit has not been observed to be altered
by the magnet; the physical arrangement of the molecules
during crystallization is always governed by directive forces
having no connection with affinity, and to the ordinary ones
is now superimposed the polarizing influence of the magnet.

A different principle is involved in Remsen's experiments,
for they depend upon the removal of particles from a mag-
netized mass of iron, and the substitution therefor of faintly-
magnetic copper. The explanation of Messrs. Rowland and
Bell must appear highly plausible, that the resistance to such
removal must protect the more highly magnetized points
from reaction, so long as there are places where the iron can
be more readily dissolved. We have here a purely mechanical
reason for the localization of the reaction, in a non-uniform
field. That the total amount of reaction would not be affected
we may infer from a recent experiment by Fossati,1 in which he
shows that the weight of iron precipitated from a solution by
zinc is not affected by the presence of a strong magnetic field.

1 Bolletino delV Elettrirista, 1890. I quote from Wiedemann's Beibtttter, 1890, p.
1010, which alone is at my disposal.

CHEMICAL ACTION AND MAGNETISM 297

Apparently inconsistent with the protection-hypothesis
are the observations of Messrs. Nichols and Franklin, which
show that iron which has become passive through the action
of strong nitric acid suddenly regains its activity when intro-
duced into a magnetic field. One might be tempted to ascribe
this to the exposure of fresh surfaces, owing to the rearrange-
ment of the molecules during magnetization; but since the
investigators have reason to seek the cause in the induction
of local electric currents by the magnet, [147] we may assign
this phenomenon to the fourth category, that of galvanic
action in the magnetic field. To my knowledge, Messrs.
Nichols and Franklin were the first to experiment upon the
effect of an unequal magnetic field upon an electrolyte: the
movement of the paramagnetic salt to the interior portions
of the field, and the inequality of electric potential consequent
upon the variation of concentration, were proved, as might be
expected. We have, then, this effect, as well as that of the
Faradic induction, to account for any irregularities which
the galvanoscope might indicate, when a solution undergoing
electrolysis was also subjected to magnetic influence. Messrs.
Nichols and Franklin do ascribe their observations to this
cause, and see no reason to introduce a supposed change of the
chemical conditions.

I fail to see any significance in the experiment of placing
one of two gas- voltameters, or one of two cells containing an
iron solution,1 in a magnetic field, and looking for a difference
in the amount of decomposition when a current is passed
through the couple in series. Surely no such result could be
expected in the face of the universally acknowledged Law of
Faraday, unless, indeed, a magnetic field were imagined to
alter the quanti valence of the elements.

To sum up : all experiments hitherto made have introduced

1 Fossati.

298 MORRIS LOEB

non-chemical phenomena, due either to the inequalities of the
magnetic field, or to the physical heterogeneity of the reacting
system, or to both of these causes at once. It was my wish to
study the effect of magnetism upon chemical reaction where
the system remained homogeneous throughout, and where the
field of stress was practically homogeneous. Such conditions
can be realized by observing the speed of some reaction which
does not involve solids, in the presence of a magnet, and, again,
when there is no magnetic effect, provided the magnetic prop-
erties of the system could be altered by the reaction. In the
same manner as an electric system is affected by its approach
to or removal from a magnetic field, we might suppose that
a reaction which made a system more or less amenable to
magnetic action might show evidence of acceleration or re-
tardation by the magnetic force. If this effect were appre-
ciable, the relation between magnetic force and affinity would
be established, and data could be obtained for calculating the
real value of magnetization.

[148] My results, however, have been negative, and I am
led to believe that no such relation exists, unless it be so slight
that my means of observation have been inadequate. Being
confident, however, that my method has been of no lower
order of delicacy than those hitherto employed in connection
with the subject, I do not hesitate to assert that the interest-
ing effects which have been noted are not due to a variation
of affinity or of chemical reaction in its strictest sense. For
this reason I herewith present my results : —

The choice of material for my investigation was rather
limited: of all compounds, the salts of the iron group alone
yield markedly paramagnetic solutions; furthermore, Wiede-
mann has shown that the ordinary form of reaction between
salts does not affect the total magnetism of the system, so long
as it involves merely an interchange of acids. But there is a

CHEMICAL ACTION AND MAGNETISM 299

marked change when the constitution of one of the ingredi-
ents is altered: the atomic magnetism of trivalent iron is
25 per cent greater than that of the same element in the fer-
rous state. I resolved, therefore, to study the effect of mag-
netism upon the speed of oxidation and reduction of iron salts
in solution by reagents which showed but a feeble magnetism
by themselves.

Two such reactions have already been studied under ordi-
nary conditions, and, inasmuch as the methods employed
seemed admirably suited to my purpose, I have followed them
in this investigation.

Dr. J. J. Hood1 determined the speed of the reaction

6FeS04+KC103+3H2SO4=SFe2(SO4)3+KCl+3H2O,

by estimating volumetrically with permanganate the amount
of ferrous salt remaining unaffected at different stages of the
process.

Meyerhoffer2 gives one series of observations upon the

reaction

2HI+2FeCl3=I2+2FeCl2+2HCl,

in which case the iodine which had been set free could be
determined with starch paste and sodic thiosulphate.

OXIDATION OF A FERROUS SALT

I had at my disposal a large Ruhmkorff electro-magnet,
with cylindrical iron cores ten inches long and three inches
thick. [149] With the poles three inches apart, and with a
current from ten storage cells, the intensity of the magnetic
field was roughly determined at 10,000 c. g. s. per square-
centimeter. For my supply of electricity I am indebted to the
kindness of the director of the Physical Laboratory, Professor
A. A. Michelson. While ten cells were usually employed, I

1 Philosophical Magazine, [5], 6, 371; 8, 121; 13, 419.

2 Zeitschr. 2, 597.

300 ; MORRIS LOEB

sometimes was enabled to use double that number, and in
several instances obtained the current directly from the dy-
namo, employing as full a current as the apparatus would
safely bear. Because the results were always virtually identi-
cal, no pains were taken to determine the exact strength of
the magnetic field, but 18,000 c. g. s. is a low estimate of the
maximum reached.

The axes of the cores being horizontal, a prismatic battery
cell, 2jx6X6 inches, was placed between the poles to serve as
a bath of constant temperature. It was therefore protected
from direct contact with the poles by thin layers of cotton
batting, and was traversed by a rapid current of water from
a reservoir whose contents were kept within 0.1° C. of the
desired temperature.

The solutions were contained in a sort of pocket-flask of
100 cc. capacity, an inch thick, and having two flat sides of
circular outline three inches in diameter. This flask was sus-
pended in the bath in such a manner as to be just between
the poles of the magnet. The solutions which were not to be
subjected to the influence of the magnet were contained in a
precisely similar flask, and the water-bath in which this was
placed was fed by the overflow from the first mentioned one.
Where it was not feasible to observe the two reactions at the
same time, especial care was taken to keep the temperature
constant.

The following solutions were employed : a one-third molec-
ular solution of potassium chlorate, a one-half molecular
solution of sulphuric acid, a one-half molecular solution of
ferrous sulphate, a solution of potassium permanganate of
which 12.5 cc. corresponded to 1 cc. of the iron solution. The
latter was made from crystallized ferrous sulphate, with a
little sulphuric acid and an excess of metallic iron, so that
it was very nearly neutral.

CHEMICAL ACTION AND MAGNETISM 301

Proper volumes of the chlorate and the acid solutions hav-
ing been run into the flask and sufficient water to make the
volume 80 cc., the solution was allowed to acquire the temper-
ature of the water-bath. Thereupon 20 cc. of the ferrous sul-
phate solution, which had been brought to the same tempera-
ture, were added [150] rapidly, the flask was vigorously shaken,
and at once replaced in the water-bath. If the magnet was to
be employed, its electric circuit was closed at this time. After
the expiration of a few minutes, 10 cc. were withdrawn from
the flask by means of a pipette, and were quickly run into a
large quantity of cold water contained in a porcelain dish,
the time being noted when the pipette was emptied. The titra-
tion was then executed as rapidly as possible. This operation
was repeated at suitable intervals, until the solution was ex-
hausted or external conditions prevented a continuation of
the observation. Where two reactions were to be observed
together, the second solution was mixed ten minutes after
the first, the same interval being preserved, as nearly as might
be, throughout. Owing to the weakness of the permanganate
solution and to varying conditions of illumination, my titra-
tions have a probable error of fully ^ to ^ cc., but this is in no
unfavorable proportion to the observed values; in cases of
over-coloration I rejected the result, rather than titrate back
with another solution. "

The reaction has been proved by Hood to be subject to the
law

at

where x—the amount of substance changed, £=time elapsed,
A and B represent the original quantities of ferrous sulphate
and chlorate respectively, and C is a coefficient depending on
external circumstances.

302 MORRIS LOEB

As equivalent quantities of A and B were used,

tj
at

Integrating, -- — = C^+constant.
A— x

Calculating this constant from the initial conditions d=

#=0, constant =—, and consequently
A.

x

At A-x

A is the amount of permanganate required at the first titra-
tion, and A -x represents the amount of each subsequent one,
after the lapse of t minutes. We possess all the data for calcu-
lating C. This coefficient has been shown by Hood to depend
upon the temperature, to be augmented by the presence of
free [151] acid, and diminished by the presence of neutral
salts not participating in the reaction. It is consequently
decreasing continually during the reaction, most noticeably,
however, toward the end. Furthermore, if magnetism is of
influence, the values of C must show it. In order to eliminate
the other influences, I have sought to take the samples from
corresponding solutions at the same intervals of time, and
have varied the conditions somewhat by changing the tem-
peratures as well as the amounts of sulphuric acid present in
different series.1 It will be seen that, while there is consider-
able variation between individual determinations, these vari-
ations are no greater between analogous samples of two cor-
responding series than between two succeeding samples of
the same series. Further, the means of the whole series agree
well with each other. The tables which I subjoin are selected,
solely with reference to their general reliability, from a larger

1 In this connection it may be interesting to note that this reaction is, according to
my experiments, barely perceptible at 0°C., — a result which agrees closely with the
limit set by Dr. Hood by extrapolation with his temperature-coefficient.

CHEMICAL ACTION AND MAGNETISM 303

mass of material, all of which gave analogous results. While
the effect of magnetism should produce acceleration, the
variations of C from that of the non-magnetic reaction are
negative quite as frequently as positive.

Series I.— KClOs+GFeSC^+SHaSC^. Temperature, 10.2°,
Series II. — Same conditions, in magnetic field (10 cells).

0 0 24-38 24-26

30-25 29-75 22-78 22-88 -049524 -048357

105 104-25 20-22 20-28 8050 7940

155-17 154-86 18-71 18-68 8011 7951

210 210 17-49 17-27 7695 7942

241 241-33 16-82 16-79 7546 7599

305-25 305-5 15-64 15-53 7491 7584

Mean -048051 -047895

Mean of last five . . . -047758 -047803

Series III. — Same relation, KClOsiFeSCX; great excess
H2SO4. Temperature, 18.7°.

Series IV. — Same as III, but with magnet (20 cells).

Series V. — Same as III, but with magnet (dynamo).
[152]

t A— x C

in rv

0 0 0 23-16 23-10 23-10 ...

20 20 20-5 18-57 18-39 18-32 -035335 .035543 -035509

40 40 40 15-33 15-45 15-41 5513 5358 , 5400

60 60 60] 13-28 13-38 13-21 5353 5241 5401

80 80-5 80 11-71 11-58 11-42 5276 5348 5534

100

100-25

100

10-41

10-45

10-40

5288

5227

5286

120

120

120

9-38

lost

9-45

5282

5211

139-75

130-75

140

8-72

8-99

8-54

5116

5197

5272

160-25

155

161

7-94

8-17

7-84

5164

5104

5233

Mean

•035292

•035288

• 035355

REDUCTION OF FERRIC CHLORIDE

The reaction 2HI+2FeCl3=l2+2FeCl2+2HCl, is not a
simple one, being reversible, and furthermore accompanied
by complicating bye-reactions. It seemed better to avoid all

304 MORRIS LOEB

attempts to obtain the reaction-coefficients, and to make
parallel experiments, with exactly the same time-intervals. If
the magnetic force had any effect, this must be visible from
the burette-readings.

The method used was exactly as before, but diluted solu-
tions were employed to prevent the loss of free iodine. Equiv-
alent quantities of hydriodic acid and ferric chloride were

allowed to react in molecular solutions, and 10 cc. were

taken out at a time and titrated with - - "normal sodium

115

thiosulphate solution. The determinations were very exact,
and the corresponding burette-readings will be found to cor-
respond so closely as to leave no doubt of the exact equality
of speed within and without the magnetic field. I give all the
series which were observed; in the second set, the reaction was
carried as far as it would go, — at least there was no more
iodine liberated after 15| hours' standing.
Temperature, 17.8°.

With Magnet (dynamo)

Na2S2O3 required

3-95

4-52

5-10

5-401

5-58

With Magnet (dynamo)

Na2S2O3 required

5-92
6-93
7-38
7-90
8-04

8-30
8-28

Without Magnet ,
Time Na2S2O3 required

\

Time

30-5 3-89

30-

60 4-80

60

120 5-10

120

180 5-55

180

231 5-60

231

[153] Same conditions.

Without Magnet
Time NaaSzOs required

\

Time

40 5-99

40

86 6-92

85

130 7-38

130

205 7-85

205

266 8-07

266

325 8-28

325

375 8-32

375

,

13301

1 Without magnet. ,

CHEMICAL ACTION AND MAGNETISM 305

Same proportions; temperature, 0°.

Without Magnet With Magnet (10 cells)

Time .NazSjOs required Time Na-jSjOs required

60 2-70 60.5 2-80

120 3-72 120 3-70

195 4-54 195 4*42

275 4-86 275 4 90

360 5-20

380 5-70 380 5-80

480 6-06 480 6-10

600 6-43 600 6-60

705 6-71 705 6-75

[263] APPARATUS FOR THE DELINEATION OF
CURVED SURFACES, IN ILLUSTRATION OF
THE PROPERTIES OF GASES, ETC.1

IN attempting the graphic representation of the relations
between the volume, temperature and pressure of gases, or of
other problems involving three variables, one is met by the
difficulty of properly constructing the surfaces in question.
Drawing isothermals, etc., as projected upon a single plane,
gives a very imperfect idea of the actual proportions. For
many years this method has been occasionally supplanted by
the actual construction, in papier mache or plaster, of models
bounded on one side by the surface in question, — relief maps,
in other words. This plan suffers from several disadvantages.
Aside from the notion of solid volume which is involuntarily
entertained in beholding such a model, some of the surfaces
are too complex to be well shown in this manner. Further-
more, the models are rather hard to make, expensive, and
occupy a good deal of room.

I have obviated most of these difficulties by obtaining a set
of glass plates, about 11 cm. square and 7 mm. thick, ruled in
squares 7mm. wide. Placed one on top of the other, these form
a block whose perpendicular edge may be taken for the third
axis in a system of rectangular coordinates. Having drawn
upon a sheet of paper the curves representing the relation
between volume and pressure as successively 0°, 10°, 20°, 30°,
etc., of temperature, I can trace them, with suitable grease-
chalks, upon the successive glass plates. When these are

1 Reprinted from Journal of the American Chemical Society, 13, 263 (1891). Also
Chemical News, 66, 220 (1892).

DELINEATION OF CURVED SURFACES 307

superposed, the curves exhibit the proper relations in space
and afford a very fair idea of the nature of the surface of which
they are elements, without arousing any sensation of an in-
cluded volume. Since the lines can always be erased and re-
placed by others, a set of twenty plates suffices for all pur-
poses, and the surfaces can be produced at a moment's notice
if the necessary sketches on paper are preserved. Besides
[264] being useful for illustrating lectures in molecular phys-
ics, the plates can also be employed to advantage in the con-
struction of crystallographic, geological and other models, j
Where the parallax, inevitable for glass plates, becomes
annoying, it is possible to substitute wide-meshed cotton
netting, stretched upon square frames of uniform thickness.
The curves can be embroidered upon the net, as it were, with
pieces of colored thread; although it is not quite so easy to
make the lines conform to the drawing, the general effect
remains the same.

[1019] NOTE ON THE CRYSTALLIZATION
OF SODIUM IODIDE FROM ALCOHOLS1

AN accidental observation during the preparation of some
ethers by Williamson's method led to the experiments de-
tailed below, which are [1020] merely presented as an addi-
tion to the somewhat restricted literature upon the addition
products between haloid salts and alcohols.

Sodium iodide is very soluble in absolute methyl alcohol
and is not precipitated therefrom upon the addition of a con-
siderable volume of absolute ether, while wet ether produces
immediate separation. On cooling a warm solution, rather
large plate-shaped crystals separate out, while a solution
saturated at room temperature and then cooled below 0°
becomes thoroughly permeated with brilliant white felted
needles; although differing markedly in appearance, these
two kinds of crystals are identical in composition.

The iodine was determined by Volhard's method; the
methyl alcohol, by heating in a current of air and absorbing
the vapors in sulphuric acid; the gain in the weight of the
latter corresponding accurately to the loss experienced by the
crystals. The results agreed very closely with the formula
NaI.3CH4O, — 38.91 and 38.55 per cent of methyl alcohol
and 51.50 per cent of iodine (calculated for NaI.3CH4O,
39.06 and 51.58 per cent).

Potassium iodide, while fairly soluble in alcohol, crystal-
lizes free from it, and this seems to be quite a characteristic
distinction between the two salts. Sodium iodide crystallizes
from ethyl alcohol, forming an addition product, although not

1 Reprinted from Journal of the American Chemical Society, 27, 1019 (1905).

CRYSTALLIZATION OF SODIUM IODIDE 309

quite so readily as with the methyl alcohol. The analysis
gave 64.29 per cent I; calculated for NaI.C2H6O, 64.91 per
cent. This, therefore, seems to be the formula of the addition
product with ethyl alcohol.

Normal propyl alcohol dissolves nearly one-third of its
weight of sodium iodide and, on evaporation at low tempera-
tures, deposits crystals which appear to have the formula
5NaI.3C3H8O, as two distinct preparations gave 68.26 per
cent, and 68.22 per cent of iodine, against 68.27 per cent re-
quired by theory. Apparently, therefore, the molecular pro-
portion of alcohol assimilated decreases as the series ascends.

THE VAPOR FRICTION OF ISOMERIC ETHERS1

THE recorded experiments on the friction of vapors, by the
transpiration method, having been made with cumbersome
apparatus and at the temperature corresponding to the boil-
ing points of the substances, it was thought important to
devise a method whereby non-saturated vapors could be
studied at identical temperatures, for the purpose of ascer-
taining whether the constitution as well as the composition
of organic compounds influences the molecular volume, of
which the vapor-friction is a function.

The apparatus used consists of a U-tube, one limb of which,
about 60 cm. long, has a bore of less than one tenth of a milli-
meter, while the bend and the other limb is just wide enough
to allow a column of mercury to descend unbroken. A stop-
cock and funnel-end are placed on the wider tube, which also
bears two marks about 50 cm. apart. The capacity of the tube
between these marks is accurately determined. The whole
apparatus can be heated uniformly, as it is surrounded by a
vapor-jacket. Before heating, the liquid to be studied is
poured into the tube and is vaporized as the temperature
rises, in such a manner as to expel all air and foreign gases.
A short column of mercury, of known length, is introduced
by means of the stop-cock, and in its descent forces the vapor
through the capillary; the time in which the lower meniscus
travels from the upper to the lower mark is ascertained by
means of a stop-watch. The method is easy and rapid, and
experiments with air gave results agreeing well among them-
selves and with the values obtained by the majority of previ-

1 In collaboration with F. S. M. Peterson. Reprinted from Science, 21, 818 (1905).

VAPOR FRICTION OF ETHERS 311

ous observers. The calculations were made according to Poi-
seulle's formula, very few corrections being necessary.

From the study of isomeric ethers, as well as ethyl alcohol,
it was found that the constitution has a decided influence
upon the internal friction of the vapor, as will be seen from
the following table, representing in each case the average
of a number of experiments. The last column gives the com-
parative volumes of the molecules according to the formula
suggested by L. Meyer, in which Y is the friction, M the
molecular mass.1

Substance Y V

Methyl ether, (CH3)2O 1133-5 55-53

Ethyl alcohol, C2H6O 1100 58-09

Methyl-ethyl ether 1030 78-2

Ethyl-ether 944-7 110-4

Methyl-propyl ether 951-8 100-74

Methyl-isopropyl ether 992-3 96-46

Ethyl-propyl ether 874-9 133-2

Di-propyl ether 797-6 170-7

Di-isopropyl ether 841-5 157-8

1 The editor has been unable to find the original source of this equation, which
is doubtless of a highly hypothetical nature.

[652] ANALYSIS OF SOME BOLIVIAN BRONZES J

THROUGH the kindness of the authorities of the American
Museum of Natural History, we were enabled to analyze por-
tions of certain implements collected in the region around
Lake Titicaca. It will be seen that these metals differ remark-
ably in composition, and indicate the possession of consider-
able metallurgical skill by the inhabitants of that region.
The absence of the slightest traces of silver may be taken as a
proof that the tin was derived from cassiterite, rather than
native tin. The composition of Specimen IV suggests its
preparation from domeykite, or some other copper arsenide,
fairly free from sulphur. Owing to the small mass of samples,
which were drilled or cut from the specimens, the density
determinations, made with water in a pycnometer, are only
approximate. In Specimen VI the porosity of the material
undoubtedly occasioned a low result. Tin and copper were
separated by potassium [653] polysulphide, the former deter-
mined as stannic oxide and the latter electrolytically. Ar-
senic was separated from copper by Crookes's method, and
sulphur was weighed as barium sulphate after oxidation with
nitric acid in a sealed tube.

I. Museum No. 1842. Small chisel or pinch-bar, 18 X l| xj
inches. Very tough. Density, 8.68.

II. Museum No. B-1840. Implement 5-6 inches long,
very hard and tough; pale color. Density, 8.94.

III. Museum No. 1959. Thick wide chisel 4| inches long,
tough but less hard. Density, %8.92.

1 In collaboration with S. R. Morey. Reprinted from Journal of the American
Chemical Society, 32, 652 (1910).

ANALYSIS OF SOME BOLIVIAN BRONZES 313

IV. Museum No. 1-859. Socketed spear-head, 12 inches
long. Density, 8.89.

V. Museum No. 2413. Fragment of pointed bar 6 inches
long. Density, 8.61.

VI. Museum No. 1949. Small cast chisel; contained char-
acteristic air-holes or "pipes." Apparently contained con-
siderable oxide. Density, 8.18 (?).

Cu..
Sn

ANALYSIS
I II III IV

. . . . 91.81 90.51 95.59 97.43
. . . 7.56 8.92 4.48

V VI

94.96 91.43
4.98 7 05

Pb

tracef?)

Fe. ..

trace trace trace trace

trace

s

trace little

053

As

2.14

99.37 99.43 100.07 99.57 100.47 98.48

To this report may be added the record of an analysis, made
in 1901, by Dr. A. E. Hill with one of us, of a figurine found
in Honduras. Color, pale yellow; density, 8.94-6. Cu. 93.19,
Sn 1.64, Pb 1.60, Fe 0.40 per cent; Au, Sb and Zn absent.

[601] STUDIES IN THE SPEED OF REDUCTIONS 1

FOR some years past, I have been conducting experiments
to ascertain whether certain phenomena due to the mixture
of derivatives of closely allied bases might not indicate the
formation of complex bases of a higher order, similar to the
well-known complex acids. The difference in the colloidal ten-
dencies of mixed and pure basic salts, the appearance of spec-
troscopic lines in a mixture of oxides, none of which emit these
lines in a pure state, the curious relation of thorium and
cerium with respect to incandescence, are among the phe-
nomena which might call for such an explanation. While my
experiments have so far failed to yield positive evidence in
this direction, I have obtained certain results which seem
worth recording for their own sake.

My first attempts concerned themselves with the possible
formation of an aluminic-ferric complex, by the hydrolysis
of the mixed chlorides. Solutions representing systematic
variations in concentration and relative proportion of ferric
and aluminic hydroxides were observed for several years and
finally analyzed, with the result that I am convinced that no
aluminum is carried down permanently combined with basic
ferric chlorides. Any temporary occlusion is compensated on
standing with the supernatant acid solution of ferric chloride.

But a complexity of these two bases might be indicated,
if the behavior of ferric chloride toward reducing agents
were affected by aluminic chloride, especially since the latter
would hardly be likely to figure as a chlorine-carrier in dilute
solutions. When these experiments yielded a positive result,

1 Reprinted from Orig. Com. Eighth International Congress of Applied Chemistry,
26, 601 (1912).

THE SPEED OF REDUCTIONS 315

other chlorides were mixed with ferric chloride to test their
effect upon its stability toward reducing agents. The method
followed closely that employed by A. A. Noyes, in studying
the speed of reaction between ferric chloride and stannous
chloride. He mixed dilute [602] solutions of these two salts
in equivalent proportions, drew measured samples from time
to time, running them into a solution of mercuric chloride,
to arrest the reaction by removing all the remaining stannous
chloride without affecting the trivalent iron; then determin-
ing the amount of the latter by titration with potassium
dichr ornate. Using twentieth normal solutions of these two
compounds, I obtained constants for the reaction agreeing
closely with Noyes's figures ; upon adding aluminic chloride,
also in twentieth normal concentration, the speed was more
than doubled; while it was quadrupled in the presence of a
tenth normal solution of aluminic chloride. Of course, such
a result might be ascribed to the excess of chlorine ions
present, especially as Noyes had found that hydrochloric acid
has an effect, though of a different kind. If so, chlorides of
divalent elements should not have so great an effect: yet
1/20 normal solutions of manganous chloride and of glu-
cinic chloride also double the speed of reduction, although
the ionization cannot be the same. A 1/20 normal solution
of quadrivalent thorium does not accelerate quite as much.
As is well known, Noyes considers this as a typical reaction
of the third order, and shows that his equation

c = l( l M

2AU-.302 A2/

applied to his experimental data, gives a fairly constant value
for Ca. My series, which I cannot reproduce in full, show about
the same degree of constancy for €3. Consequently, I think it
fair to assume that the reaction remains of the same type,

316 MORRIS LOEB

and that the variations in speed are due to the specific in-
fluences of the metals concerned. For, as will be seen, the
accelerations are not exactly the same. I give average values
of c3, always for the reaction between 1/20 normal ferric
and stannous chlorides.

C3

Without admixture 67-8

With 1/20 A1C13 149-6

With 1/20 MnCl2 161-2

With 1/20 G1C12 159-4

[603] With 1/20 ThCl4 157-0

With 1/10 Aids 288-1

With 1/10 MnCl2 266-4

With 1/20 SnCl4 225-0

With 1/40 SnCl4 131-0

The last two values are anomalous; but expectedly so, as
this compound enters into the original reaction.

Noyes has found that the addition of free hydrochloric
acid alters the nature of the reaction, so that it becomes
one of the second order. I find that several chlorides, nota-
bly zirconium chloride and oxy chloride, have a similar effect.
The reason must be different from Noyes's explanation, based
on free chlorine ions.

Another series of experiments, with the same fundamental
object, sought to study the influence of analogous compounds
on eerie sulphate. Cerium, alone of the so-called rare-earth
group, lends itself to studies in oxidation and reduction,
although virtually no work has been done in following these
changes quantitatively. Of the salts of the tetravalent base,
only the sulphate is stable in aqueous solution, and then only
in the presence of much free acid. On standing, its orange
color fades very slowly, a marked odor of ozone indicating
the by-product of its reduction to the cerous state. Indeed,
I am doubtful whether I have ever had a solution of the
tetravalent salt, free from any trivalent admixture. After
many trials I found that a fair idea of a reduction speed might

THE SPEED OF REDUCTIONS 317

be obtained by mixing cerium sulphates and glucose in equi-
molecular amounts in dilute solution, maintaining at 25° C.,
and titrating samples with very dilute hydrogen dioxide solu-
tion, which instantaneously completes the decolorization of
the eerie salt. The reaction with glucose is completed in about
two hours and can be readily followed in 15-minute intervals.
Of course, the stability of the hydrogen peroxide standard
was meanwhile controlled with permanganate solution.

For some unexplained reason, the reaction as studied by
me does not follow a logarithmic law: the amount of cerium
reduced is simply proportionate to the elapsed time, so that
x/t is pretty nearly constant for every individual series. So
anomalous a [604] behavior naturally precludes any claim
on rigid deduction. But the experiments had comparative
values, when they were compared with others, in which equiv-
alent quantities of lanthanum sulphate and thorium sulphate
had been mixed with the solution of cerium salts.

Values of x/Wt

Pure eerie solution 694.8,693.1,

With thorium 708,697

With lanthanum 665.1,658.1

Here again, the influence of the cognate metal seems un-
mistakable and distinctive. My only explanation lies in the
complexity of the base, although I admit that the evidence,
so far, is not conclusive.

APPENDIX

LABORATORY MANUAL1

LIST OF APPARATUS FURNISHED FOR THIS COURSE

1 Notebook, 1 Bent ignition tube,

1 Manual, 2 Glass rods,

1 Pipestem triangle, 1 Meter glass tubing,

1 File, 2 Watch-glasses,

1 Horn spatula, 2 Rubber stoppers,

1 Steel forceps, 2 Cardboard boxes.

Test-tube holder, 1 Package filters,

Test-tube brush, 10 cm. black rubber tube,

Wire gauze, 1 10 cm. graduated cylinder,

Porcelain dish, 1 Box of weights,

Porcelain crucible, 1 Pair of scales,

Porcelain lid, 1 Towel.

Glass U-tube,

Bunsen burner, 12 Test-tubes,

Hose for same, 2 Funnels,

1 Star for same, 1 Long-stemmed funnel,

1 Chimney for same, 1 200 cc. flask,

1 Wing-top for same, 1 750 cc. flask,

2 Iron rods, 1 Set wash-bottle fittings,
2 Iron rings, 3 Small beakers,

1 Pneumatic trough, 2 Common bottles, small,

1 Test-tube rack, 1 Common bottle, large.

This apparatus is loaned to the student on the distinct understanding that it
remains the property of the laboratory. It must not be carried away, nor put to
improper uses. Each student is held responsible for the apparatus issued to him, and
will be obliged to return the apparatus clean and in good condition when surrender-
ing his desk, or pay for what is missing.

Compare the above list carefully with the apparatus in your desk. Call attention
to any imperfections and satisfy yourself that nothing is missing. Do not leave any
apparatus outside your drawer and cupboard, when leaving the laboratory, and see
that the drawer is fastened and the cupboard locked.

When the desk is surrendered, all apparatus which is returned clean and in good
condition will be credited in full; pieces which are dirty or damaged, but still fit
for some use, will be credited at half price. Particular attention is called to the neces-
sity of taking good care of the weights and balances.

HYDROGEN

To generate this gas : — After convincing yourself that the
generating apparatus does not leak, remove the cork, and put

1 Prepared for students in Elementary Inorganic Chemistry at New York Uni-
versity.

322 APPENDIX

sufficient granulated zinc into the bottle to completely cover the
bottom. Replace the cork, pour enough water into the bottle to
seal off the lower end of the funnel-tube. Add strong hydrochloric
acid, a little at a time, and in such a manner that air-bubbles shall
not be carried down with it. Whenever the evolution of the gas
becomes less brisk, more acid should be added.

CAUTION: No flame should be allowed anywhere near a hydrogen generator
until gas has been evolving briskly for at least five minutes ! ! Do not actually apply
a flame to any portion of the apparatus, until a test, according to Exp. 1, shall have
proved the absence of an explosive mixture !

EXPERIMENT 1. To test whether air has been entirely displaced
by hydrogen: — Pour so much water into the "pneumatic trough "
that the perforated shelf is well covered. Immerse a test tube until
it is quite full of water; raise the closed end out of the water, and
rest the tube with its opened end upon the shelf. Bring the delivery-
tube of the gas generator into such a position that the escaping
bubbles rise into the test-tube and displace the water contained in
it. When the tube is quite full of gas, close it with your thumb and
carry it to a lighted burner, not removing your thumb until the
mouth of the tube is close to the flame. If the gas lights with a faint
sound, and the flame works its way quietly down the tube, no air
was mixed with the hydrogen in the generator; but, if the gas
burns all at once, with more or less of an explosion, air was still con-
tained in the generator at the time the sample was taken. Repeat
the experiment, until a sample burns quietly.

NOTE that this experiment must be repeated every time that the generator is set
up afresh. The small volume and the thin walls of the test-tubes make these ex-
plosions harmless, whereas a similar explosion in the generator might lead to danger-
ous injuries.

EXP. 2. To compare the density of hydrogen with that of air.
Fill two test-tubes over the pneumatic trough with hydrogen:
hold one, mouth up, for ten seconds, then approach the mouth
to the flame; hold the other, mouth down, for ten seconds, and
approach to the flame. Note and explain any difference.

EXP. 3. Connect the inner tube of the "osmose-apparatus"
with the hydrogen generator, by means of a bit of rubber tube.
The pipe-bowl will be filled with hydrogen in a little more than two
minutes. Pull out the inner tube and set the open end of the outer

APPENDIX 323

tube under water. Observe what happens, and ask for an oral ex-
planation.

EXP. 4. If a test-tube is only partially filled with water, closed
and inverted with its mouth under water, hydrogen being then
introduced, a mixture will be formed of the air left in the tube,
with the volume of hydrogen represented by the quantity of water
originally placed in the tube. Fill four test-tubes one-quarter, one-
third, one-half, and two-thirds, respectively, full of water; invert
in pneumatic trough, displace the water with hydrogen; close with
thumb, carry to flame and compare violence of explosions.

EXP. 5. Dry the end of the delivery-tube with a bit of filter-
paper. Allow the gas to flow upon bits of moist litmus paper, red
and blue : note whether their color is affected.

EXP. 6. Wipe a beaker clean and dry; then hold it for a min-
ute or more over the mouth of the delivery-tube and note whether
anything is deposited upon the beaker. Light the hydrogen as it
issues from the tube, and again hold the beaker over the jet.

EXP. 7. Fill a small bottle with hydrogen over the pneu-
matic trough. Lifting the bottle, mouth down, out of the trough
with your left hand, push a lighted match well up into it, holding
the match by means of the steel forceps, with your right hand.

EXP. 9. Disconnect the generating apparatus, and filter its
liquid contents into an evaporating dish, being careful not to fill
the latter above the lip; the superfluous liquid may be thrown away
and any undissolved zinc can be left in the generator, for future
use. The small stove in the draught-closet is lighted, the porcelain
dish set upon it and heated with a small flame until the liquid has
all evaporated. As this operation takes some time, and requires
little attention, it can be conducted during the progress of some
of the succeeding experiments.

Write the equation which expresses the action of hydrochloric acid upon zinc.

OXYGEN

EXP. 10. Heat about one gram of potassium chlorate in a
clean, dry test-tube, being careful not to allow the flame at any time
to strike that portion of the tube which is above the substance, since

324 APPENDIX

this is apt to cause the tube to break. When the salt has melted
and a brisk evolution of gas is taking place, hold a glowing splin-
ter of wood to the mouth of the tube. Heat the fluid salt until no
more gas is seen to be given off, and then set aside to cool (proceed-
ing meanwhile with Exps. 11 and 12). When the tube is quite cold,
add some distilled water and warm, until a portion of the fused
mass has dissolved. Filter the solution into a clean test-tube, add
two drops of nitric acid and five drops of a solution of silver nitrate.

EXP. 11. Dissolve about one-fourth gram of potassium chlorate
in distilled water and add two drops of nitric acid; then five drops
of silver nitrate.

EXP. 12. — Dissolve about one-fourth gram of potassium
chloride in distilled water and add two drops of nitric acid; then five
drops of silver nitrate.

What is the behavior of potassium chlorate, and of potassium chloride, respec-
tively, toward nitric acid? toward silver nitrate? If a precipitate forms,
what must it be ? What conclusion can be drawn as to the nature of the solu-
tion obtained in Exp. 10 ? Write the equation expressing the result of heating
potassium chlorate.

EXP. 13. Clean, dry and weigh a porcelain crucible and lid.
Add about one gram of potassium chlorate to the crucible, and re-
weigh exactly. The difference between the first and second weigh-
ings will give the precise amount of salt used. Set the crucible
upon a pipe-stem triangle, supported on an iron ring and stand,
and heat gradually with a Bunsen burner, until all the oxygen has
been expelled. This can be done without any danger of loss from
spattering, if the heating is conducted uniformly and slowly. When
the salt is in quiet fusion, allow the crucible to cool to room tempera-
ture, then weigh. The loss of weight will indicate the quantity of
oxygen driven off. How much oxygen is contained in one hundred
parts of potassium chlorate?

EXP. 14. To ascertain the density of oxygen gas. The appa-
ratus furnished for this experiment consists of a tube filled with a
mixture of potassium chlorate and black oxide of manganese — for
generating oxygen, — a U-tube containing strong sulphuric acid,
and a delivery tube. The U-tube serves to prevent the escape of
everything but oxygen. Place this apparatus, with the exception

APPENDIX 325

of the delivery-tube and its stopper, upon one pan of the balance,
and exactly counterpoise it with sand, poured into a beaker upon
the other pan. This counterpoise must not be disturbed until the
experiment has been completed. Connect the apparatus up with a
delivery-tube and support it so that the heating-tube is in a slanting
position, while the end of the delivery-tube dips under the mouth of
a large bottle filled with water, and set inverted upon the shelf of
the pneumatic trough. Gradually heat the mixture in the tube,
holding the burner in your hand, and keeping the flame brushing
along the tube. Once heating is commenced, it must not be inter-
rupted until no more gas is seen to leave the delivery-tube : remove
the latter, with its stopper, from the U-tube; and then take away the
flame and allow the apparatus to grow cold. (Removing the flame
before the delivery-tube was disconnected might cause water to rise
back into the apparatus, owing to the contraction of the cooling
gas.) When the apparatus is cold, place the same parts upon the
balance pan, as before: but a certain amount of weights must be
added to this pan, to bring it into equilibrium with the original
counterpoise. This weight should be noted, as it represents the mass
of oxygen which has been transferred from the tube to the bottle.
We must now proceed to measure the volume occupied by this
mass. Note the temperature of the air near the bottle. Raise the
bottle slightly from its shelf, slip a piece of smooth paper under its
mouth, and invert dexterously, without spilling any of the water
from the bottle. No effort need be made to retain the oxygen, as
its volume is indicated by the contents of the bottle above the
water level. Fill the bottle brimful from a measuring-glass, being
careful to ascertain the number of cubic centimeters of water re-
quired to complete the filling, as they represent the volume of oxy-
gen at the temperature of the room, t°. To reduce this volume to

O^Q

0°, multiply it by the fraction - — •

273 +2

Knowing the volume and the mass of the oxygen produced in
this experiment, calculate the weight of one liter of oxygen gas.

RELATIONS OF COMBINING WEIGHTS

EXP. 15. Weigh a clean watch-glass, place about half a gram
of granulated zinc upon it, and weigh accurately. The difference

326 APPENDIX

between this weight and that of the empty glass is recorded as the
exact weight of the zinc used. Thoroughly clean the hydrogen
generator, and raise the delivery-tube in the stopper, so that its
end is flush with the bottom of the stopper. With the aid of your
wash-bottle rinse the zinc from the watch-glass into the generator-
bottle; arrange a bottle, as usual, in the pneumatic trough; but set
the gas generator in such a position that the delivery-tube is not
under the receiver. Pour one drop of copper sulphate into the
funnel, and then so much water that all the air is driven out of
the gas-generating apparatus. Now push the end of the delivery-
tube under the receiver, and pour 10-15 cc. of strong hydrochlo-
ric acid down the funnel tube, cautiously avoiding the carrying
down of air bubbles. The evolution of gas will begin at once;
should it slacken before the zinc has disappeared, more acid
may be added. (The solution of the zinc takes time, and the suc-
ceeding experiment may be commenced at this point.) When the
zinc has all been dissolved, pour enough water down the funnel to
drive all remaining gas from the generator into the receiver. The
volume of this gas is now measured and reduced to zero, after
ascertaining its actual temperature — exactly as in Experiment 14.
A cubic centimeter of hydrogen, at zero, weighs approximately
.00009 gram; what mass of hydrogen was evolved in this experi-
ment ? How many parts of zinc would displace one part of hydro-
gen from its combination with chlorine ?

EXP. 16. Weigh a clean and dry porcelain dish as accurately
as possible, add about two grams of zinc and weigh again. Pour
small quantities of dilute hydrochloric acid into the dish, until the
zinc is all dissolved; profuse addition of acid would result in loss
of time. When the zinc has been dissolved, evaporate carefully to
complete dryness on the evaporating stove, then transfer the dish
to a triangle supported on a ring-stand, where it is cautiously
heated until the zinc chloride has just melted, the burner being
held in the hand, and the flame being allowed to play down upon
the salt. As soon as the latter has melted, cool without delay. As
soon as the dish is cool enough to handle without burning the
fingers, it may be set in cold water — of course without moistening
its contents — so as to reach room temperature more quickly. Its
outside is at once wiped clean and dry and it is reweighed, the

APPENDIX 327

gain being held to represent the chlorine which has combined
with the zinc. How much chlorine would be required for one part
of zinc ? How much for one part of hydrogen ?

EXP. 17. Brighten a piece of magnesium ribbon, and weigh
off exactly .04 grams upon a watch-glass. Place the magnesium
in a beaker, and cover it with a small, short-stemmed funnel, in-
verted in the beaker. Fill the latter with water. Fill a eudiometer
with water, cover its mouth with a bit of bibulous paper, so as to
be able to invert it, and set it so that its rim rests on the funnel
in the beaker, with the stem of the funnel projecting into the eudi-
ometer. Remove as much water from the beaker as possible without
exposing the open end of the eudiometer, and pour a considerable
amount of strong hydrochloric acid into the beaker, allowing it to
run down the walls, so as to form a layer at the bottom. It will soon
work its way to the magnesium, which will quickly dissolve, the dis-
placed hydrogen rising into the measuring tube. When the reac-
tion is completed, the beaker is again filled brimful, the eudiometer
slipped off the funnel, closed with the thumb and transferred to a
tall cylinder full of water, where it is allowed to remain for some
time. The barometer having been read, and the temperature of the
water in the cylinder having been noted, the eudiometer is lifted
until the water within it stands at the same level as that without,
and the volume of enclosed hydrogen is read off on the engraved
scale. The calculation of the corresponding mass will be explained
orally.

EXP. 18. Weigh a porcelain crucible and lid, after cleaning
and drying them. Add about .8 gram of bright magnesium ribbon,
and weigh again. Set the crucible on a pipestem triangle, on a
ring-stand, and heat gradually without removing the lid, except-
ing for a moment or two at a time to admit fresh air, and observe
whether the magnesium has all been burned. Avoid the escape of
a white smoke. When all the magnesium appears to have burned,
remove lid and heat crucible more strongly. Cool, weigh crucible
with lid and contents. The gain in weight represents oxygen. In
what proportion did the two elements combine ?

EXP. 19. Charge the hydrogen-generator with some zinc, and
replace the deli very- tube with a bent tube leading to a U-tube con-

328 APPENDIX

taining a little strong sulphuric acid. The farther end of the U-tube
communicates with a hard-glass tube, by means of a connecting
tube and stoppers. While the hydrogen is sweeping the air out of
the generator and its connections, weigh the hard-glass tube, fill
about half -full of copper oxide, and reweigh. After assuring yourself
that the air has been driven out of the generator according to Exp. 1,
for which purpose the delivery-tube may be temporarily connected
on, put the copper oxide tube in position, supporting its free end
with the aid of the ring-stand. Allow a minute for sweeping the air
out of this tube, then commence to warm it gradually with a Bunsen
flame. Soon steam will issue at the jet, and care must be taken to
keep the whole tube beyond the oxide so warm that water may not
condense and run back to crack the tube. Whence does this steam
come ? Observe what happens to the copper oxide. When the
change is complete, allow the tube to cool without interrupting
the flow of hydrogen. When cold, disconnect and reweigh. With
these data, calculate the ratio in which copper and oxygen combine.

EXP. 20. Weigh a porcelain crucible without the lid, add about
1 gram of finely divided copper, and reweigh. Fill the crucible
about a quarter full of nitric acid, cover with a watch-glass, convex
side down, and heat very gently until the copper is dissolved; lift
off the watch-glass and, with a wash-bottle, rinse down into the
crucible the green drops that may have collected on it, and evapo-
rate the contents of the crucible to dryness on the stove. When
dry, remove with forceps to pipe-stem triangle, and heat over the
free flame, cautiously at first, but more strongly toward the end,
until all the green copper nitrate has been converted into black
copper oxide. Cool and weigh. The gain represents the oxygen
which is now combined with the original copper. Compare these
two weights with one another.

ALKALI METALS

EXP. 21. Remove the kerosene from a small piece of sodium
with some dry filter-paper. Drop it, in small bits, into water con-
tained in a porcelain crucible, keeping a lid on the latter, as long as
chemical action is taking place. When the sodium has disappeared,
take a drop of the solution upon the end of a glass rod, and touch
it to a piece of red litmus paper; then add hydrochloric acid, drop

APPENDIX 329

by drop, until the liquid shows an acid reaction. Write the two
equations involved. The liquid in the crucible may now be evapo-
rated to dryness, and the product examined.

EXP. 22. Counterpoise a beaker upon the scales and add 25
grams of a "normal" hydrochloric acid, — one gram of which
contains .0365 grams of HC1. — Warm this gently, set over a wire
gauze. Meanwhile, place something more than two grams of sodium
carbonate in a porcelain dish, and weigh (the weight of the empty
dish being unimportant). Carefully transfer this salt, a little at a
time, to the acid, by means of a horn spatula, until the liquid is
faintly alkaline. Reweigh the dish to find the amount of sodium
carbonate required to neutralize the acid.

EXP. 23. Repeat experiment 22, using potassium carbonate in
place of sodium carbonate, and compare the two results.

EXP. 24. Pour 100 cc. of calcium hydroxide into a clean flask.
Dissolve a quarter of a gram of sodium carbonate in half a test-
tubeful of water, and add just enough of this solution to the
flask to complete the precipitation. When a drop produces no
further precipitate, add a few drops of the calcium hydroxide;
filter and neutralize the filtrate with hydrochloric acid, noticing
whether there is any effervescence. Pour a few drops of acid upon
the precipitate on the filter and note the result.

EXP. 25. Weigh a clean porcelain crucible. Add one gram of
potassium chloride and reweigh. Add 5 to 6 cc. of dilute sulphuric
acid. Heat gradually in fume-closet until dry; allow the crucible
to cool, and moisten the contents with a little more sulphuric acid;
evaporate to dryness. Remove crucible to pipe-stem triangle
supported on ring-stand and heat with Bunsen burner, but not
sufficiently to melt the salt. Cool and weigh. The crucible now con-
tains acid potassium sulphate, KHSO4.

EXP. 26. Mix on a piece of filter paper about two grams of
solid ammonium chloride with about three grams of powdered cal-
cium oxide. Pour the mixture into a specimen tube and close the
latter with a perforated stopper, through which passes a straight
glass tube. Over this tube slip an inverted test-tube, to the mouth
of which a piece of moistened red litmus paper has been made to

330 APPENDIX

adhere. Hold the specimen tube in a wire support, and heat the
solid mixture gently; ammonia will be given off, as can be recognized
by the litmus paper. When the test-tube appears to be well filled
with the gas, remove it from the generating apparatus and hold its
open end under the surface of some water contained in a beaker.

EXP. 27. Place a few cubic centimeters of ammonium chloride
solution in an evaporating dish, add 4 to 5 drops of potassium hy-
droxide. Test the mixture with litmus paper. Now warm, holding
pieces of moistened red litmus paper above the surface of the liquid
until no more alkaline gas is given off. Test the solution with red
litmus paper.

EXP. 28. Place a little dry ammonium chloride in the bottom of
a dry test-tube and warm until the salt has volatilized. It will be
observed to condense into crystals upon the cold walls of the test-
tube. This is called "sublimation."

CALCIUM GROUP

EXP. 29. Weigh a clean porcelain crucible; add about one gram
of calcium carbonate, weigh again. Heat on pipe-stem triangle
gradually, using chimney on burner, for about fifteen minutes. Cool,
weigh. The loss represents carbon dioxide. Pour some water on the
residue, and note behavior. Test with litmus paper.

EXP. 30. Hah* fill a test-tube with calcium hydroxide solution.
Pass in carbon dioxide by means of a clean glass tube until the
precipitate which has first formed re-dissolves. Write two equations
to express what has taken place. The solution that you obtained is
to be divided into three parts and used in the three succeeding
experiments.

EXP. 31. To one-third of the above solution add calcium hy-
droxide solution.

EXP. 32. Dilute"another portion to ten times its volume with
distilled water, in a flask. Add twenty drops of soap solution and
shake vigorously.

EXP. 33. The last portion is to be boiled, filtered into a per-
fectly clean flask, diluted to ten times its volume with distilled
water. Add twenty drops of soap solution, and shake vigorously.

APPENDIX 331

EXP. 34. Weigh about a gram of gypsum carefully in a porce-
lain crucible, heat strongly, cool and reweigh. Heat a second time,
to see whether a second loss of weight occurs. This loss of weight
is due to the driving off of water of crystallization. How much
water was present in the natural gypsum ? Shake the residue into
a watch-glass, stir up with a few drops of water, and observe the
result.

EXP. 35. Prepare three test-tubes containing calcium chloride,
strontium chloride, and barium chloride, respectively, each diluted
with about four times their volume of water. To these three test
tubes add equal quantities of calcium sulphate solutions (about 25
drops for each). Observe and discuss results.

ZINC, CADMIUM, AND MAGNESIUM

Hydrogen sulphide, which is used in this exercise, may be obtained from taps in
the room set apart for the purpose. The student must affix his own glass
tube to the rubber hose set on these taps. As the number of outlets is limited,
considerable time will be saved if the students will prepare the solutions
required for the following four experiments at one time, and carry the test
tubes on a rack into the sulphuretted hydrogen room. If the gas is passed into
the test tubes in the prescribed order, the glass delivery tube need not be
cleansed between the experiments. It should finally be cleaned with a little
strong acid.

EXP. 36. Dilute about 5 cc. of zinc chloride with an equal
amount of water. If the solution is acid, neutralize as nearly as
possible with ammonium hydroxide. Treat with hydrogen sulphide.

EXP. 37. Acidify a similar solution of zinc chloride with hydro-
chloric acid and treat with hydrogen sulphide.

EXP. 38. Dilute about 5 cc. of cadmium chloride solution to
one-half its original strength. Acidify with hydrochloric acid and
treat with hydrogen sulphide.

EXP. 39. Mix approximately equal volumes of the solutions of
zinc and cadmium chlorides. Dilute somewhat, acidify with hydro-
chloric acid and pass hydrogen sulphide into the mixture until no
more precipitate forms. Separate the precipitate from the solution
by filtration, allowing the liquid to run into an evaporating dish.
Set the latter upon the evaporating stove in your fume closet
and concentrate to dryness. Meanwhile wash the precipitate once

332 APPENDIX

with distilled water. Perforate the filter with a sharpened match-
stick, rinse its contents into a test-tube with the aid of a wash
bottle. Allow the solid to settle and pour off as much as possible
of the water. Add 5 cc. of hydrochloric acid. Warm until the
precipitate has dissolved. Boil for 4 or 5 minutes. Nearly neutral-
ize with ammonium hydroxide and add ammonium carbonate.

The concentrated filtrate is poured from the evaporating dish into
a test-tube, diluted, rendered alkaline with ammonia and treated
with hydrogen sulphide.

EXP. 40. To a solution of magnesium sulphate add ammonium
hydroxide solution.

EXP. 41. To 5 cc. of magnesium sulphate solution add 5 cc.
of ammonium chloride solution, then add ammonium hydroxide
solution.

EXP. 42. To the solution obtained in the last experiment, add
hydrogen sodium phosphate solution.

ALUMINUM

EXP. 43. Dilute a little aluminum sulphate solution and add
an excess of ammonium hydroxide solution.

EXP. 44. Prepare, in separate test-tubes, very dilute solutions
of potassium hydroxide and of sulphuric acid, and study their ac-
tion upon aluminum sulphate, as follows : —

Dilute 10 cc. of the aluminum sulphate solution with an equal
bulk of water and add potassium hydroxide, drop by drop, until a
precipitate, which forms at first, disappears upon shaking the test-
tube. Divide the solution into equal halves (a) and (b). Acidify
portion (a) with dilute sulphuric acid, drop by drop, until the pre-
cipitate, which forms at first, again disappears. Reunite portions
(a) and (b) . Write five equations expressing the various reactions
that have taken place.

EXP. 45. Mix, upon a watch-glass, concentrated aluminum sul-
phate solution with concentrated potassium sulphate solution.

EXP. 46. Throw a little aluminum foil into a test-tube con-
taining some strong hydrochloric acid.

APPENDIX 333

EXP. 47. Throw some aluminum foil into a test tube containing
some strong potassium hydroxide solution and warm gently.

EXP. 48. Hang two strips of cotton, one of which has been soak-
ing in a solution of aluminum acetate, over a glass rod, and suspend
them in a solution of logwood for five minutes. Remove them to a
beaker and wash with plenty of water. Observe whether the dye
adheres more firmly to one sample than to the other.

MERCURY

NOTE. As mercury and its compounds corrode lead pipes, the slops must be
thrown into jars specially provided, and not into the sink.

EXP. 49. Place about 5 cc. of mercurous nitrate solution in a
test-tube, and dilute with an equal amount of water, then add
potassium hydroxide.

EXP. 50. Dilute 5 cc. of mercuric nitrate solution with an equal
quantity of water and add potassium hydroxide.

EXP. 51. Add hydrochloric acid to mercurous nitrate solution.
EXP. 52. Add hydrochloric acid to mercuric nitrate solution.

EXP. 53. Add stannous chloride solution, drop by drop, to a
test-tube half filled with mercuric chloride solution.

EXP. 54. Allow a drop of mercurous nitrate to remain for a few
moments on a clean copper surface, rinse the copper in a little water,
wipe dry with filter-paper, then heat in flame.

TIN AND LEAD

EXP. 55. Allow hydrogen sulphide gas to act on stannous
chloride.

EXP. 56. Allow hydrogen sulphide gas to act on stannic
chloride.

EXP. 57. Drop some tinfoil into a test-tube with hydrochloric
acid and observe effect in cold and heat.

EXP. 58. Place tin-foil in a crucible, set the latter inside the
fume-closet and add strong nitric acid.

334 APPENDIX

EXP. 59. Treat some litharge (PbO) with dilute nitric acid
until dissolved. Test a portion of the solution with hydrochloric
acid.

EXP. 60. Place a few grams of "red lead" in a test-tube, half
fill the latter with cold dilute nitric acid and shake. Filter the solu-
tion from the brown residue, and test the former with a few drops of
hydrochloric acid. What has gone into solution? What is the brown
residue ? What can we conclude as to the nature of "red lead" ?

EXP. 61. Add hydrochloric acid to 10 cc. of lead acetate solu-
tion, in a test-tube, as long as a precipitate continues to form. Al-
low the latter to settle, pour off the clear liquid, shake the precipi-
tate with about 10 cc. of fresh water, allow to settle and pour off
water. Repeat this washing and then half fill the test-tube with
water, heat to boiling and filter, if necessary, into a clean test-tube.
It is well to have the filter ready in advance, as the liquid must be
filtered boiling hot. Cool the clear filtrate by running water over the
outside of the test-tube.

EXP. 62. Precipitate 10 cc. of lead acetate with potassium
iodide and proceed as in Exp. 61.

CHROMIUM AND MANGANESE

EXP. 63. Render chromium sulphate solution alkaline with
potassium hydroxide.

EXP. 64. Acidify chromium sulphate solution, and note whether
hydrogen sulphide gas affects it.

EXP. 65. Acidify some potassium chromate solution, pass in
hydrogen sulphide until the test-tube smells strongly of the gas,
filter and add potassium hydroxide to the filtrate.

EXP. 66. Add sulphuric acid to 15 cc. of potassium chromate
solution in a dish until the color has changed completely. Evapo-
rate until crystals commence to form. Then set aside to cool.

EXP. 67. Add potassium chromate to lead acetate.

EXP. 68. Mix a little manganese dioxide with sodium car-
bonate powder on a porcelain crucible-lid. Set on a pipe-stem
triangle and heat until the mass is fused. Cool, set in a beaker, dis-

APPENDIX 335

solve the melt in water, add sulphuric acid. Note any changes
of color.

EXP. 69. Dilute 1 cc. of stannous chloride in a beaker with
25 cc. of water; add 5 cc. of hydrochloric acid. Stir, and add
potassium permanganate solution drop by drop. What is taking
place ?

IRON

EXP. 70. Add ammonium hydroxide to ferrous sulphate solu-
tion.

EXP. 71. Add ammonium hydroxide to ferric chloride solu-
tion.

EXP. 72. Add 2 cc. dilute sulphuric acid to 5 cc. of ferrous
sulphate solution, then 10 drops of nitric acid, and heat. Observe
that the solution becomes almost black and suddenly clears, giving
off red fumes. Add a couple of drops of nitric acid and continue
doing this until no more red fumes appear. Cool and render alka-
line with ammonium hydroxide.

EXP. 73. Add some hydrochloric acid and a little metallic iron
to 10 cc. of ferric chloride solution. As soon as this solution has
become colorless, filter into a fresh test-tube, and add ammonium
hydroxide.

EXP. 74. Add stannous chloride to ferric chloride, until color-
less, and then make alkaline with potassium hydroxide.

EXP. 75. Dilute a little ferrous sulphate in a beaker with
water, add a few drops of sulphuric acid, and then potassium per-
manganate, drop by drop.

EXP. 76. Add potassium ferrocyanide to ferrous sulphate.

EXP. 77. Add potassium ferrocyanide to ferric chloride.

EXP. 78. Add potassium ferricyanide to ferrous sulphate.

EXP. 79. Add potassium ferricyanide to ferric chloride.

EXP. 80. Add potassium sulphocyanate to ferrous sulphate.

EXP. 81. Add potassium sulphocyanate to ferric chloride.

336 APPENDIX

COPPER

EXP. 8£. Test the action of hydrochloric, nitric and hot sul-
phuric acids on copper, noting the fumes that are given off in each
case.

f EXP. 83. Dilute 5 cc. of copper sulphate solution with an equal
quantity of water. Add small bits of iron and heat. What changes
take place?

! EXP. 84. Add potassium hydroxide to copper sulphate solu-
tion until it is strongly alkaline.

EXP. 85. Add ammonium hydroxide to copper sulphate drop
by drop, amid constant shaking, until the solution is alkaline.

1 EXP. 86. Weigh out .4 gram of crystallized copper sulphate
(which contains about .1 gram of copper), and dissolve in 9.6 cc.
of water. Measure 1 cc. of this solution into a test-tube and mix
with 9 cc. of water. To a portion of this diluted solution add a few
drops of ammonium hydroxide; of the remainder, measure 1 cc.
into a fresh test-tube and mix with 9 cc. of water. Test a portion of
this more dilute mixture with ammonium hydroxide, and proceed
as before, always preparing a solution one-tenth as strong as the
preceding one, until a drop of ammonium hydroxide fails to pro-
duce a noticeable coloration. Calculate the amount of copper per
cubic centimeter that is required to give a visible reaction with
the ammonium hydroxide.

EXP. 87. Add potassium ferrocyanide to dilute copper sul-
phate solution.

EXP. 88. Weigh a crucible; add about two grams of crystallized
copper sulphate; weigh again. Heat carefully until the salt is quite
white; cool, and reweigh. How much water did the crystals contain?
Add a drop of water to the white residue.

SILVER

EXP. 89. Add hydrochloric acid, little by little, to 5 cc. of sil-
ver nitrate until no more precipitate is formed. Throw the pre-
cipitate upon a filter and wash. Then open out the filter and

APPENDIX 337

expose the precipitate to the daylight in such a manner that a
portion is covered by something opaque. Examine from time to
time.

EXP. 90. Add enough hydrochloric acid to silver nitrate solu-
tion to effect complete precipitation. Add an excess of ammonium
hydroxide, and shake vigorously. Acidify with nitric acid; add
more ammonium hydroxide.

EXP. 91. Add hydrochloric acid to 5 cc. of silver nitrate solu-
tion; allow the precipitate to settle; pour off the clear liquid; add
water to wash the precipitate; pour off the wash- water. Shake the
precipitate with a solution of sodium thiosulphate.

EXP. 92. Clean a test-tube very thoroughly by heating nitric
acid in it. Pour away the acid and introduce 5 cc. of silver nitrate
solution. Add ammonium hydroxide until the precipitate which
formed at first is redissolved. Add a few cc. of grape sugar solution
and warm gently until the silver is deposited. Pour the liquid
away, and examine the color of the silver by transmitted light.

LABORATORY MAXIMS

There is no such phrase as " clean enough."
Never scrub off to-morrow what you can dissolve to-day.
Towels are used for drying, not for rubbing off dirt.

Neighbors' eyes were not meant for targets, nor their noses for
fume-receptacles .

Glass and porcelain are not able to stand sudden changes of
temperature.

Weights and hot crucibles should not be held in the fingers.

Note-books have good memories; jottings on loose paper are
useful when you can find them.

An unrecorded experiment was never begun.

Chemical equations explain reactions, but do not describe them.

Too much of a reagent is as bad as too little; and the latter
fault can be remedied.

Repairing damages takes much longer than avoiding them.

338 APPENDIX

The following series of lecture experiments, taken from the notes of one of Pro-
fessor Loeb's lectures on physical chemistry, may find a fitting place here, at the
close of the elementary experiments. The outcome illustrates the point of view taken
by the first paper (pages 1 to 20) of this volume. [EDITOR.!

I DESIRE to show you a series of experiments devised by Pro-
fessor Landolt, of Berlin, illustrating a class of phenomena that
are grouped together under the name of Speeds of Reaction. In
this particular case we shall examine the rapidity with which a re-
action takes place between iodic acid and sulphurous acid. In the
first place, the sulphurous acid serves to reduce the iodic acid to
hydriodic acid, which as soon as the sulphurous acid is exhausted
will react with any remnant of the iodic acid, producing water and
free iodine. Up to the moment that the last particle of sulphurous
acid has disappeared, or rather, been converted into sulphuric acid,
it is impossible that iodine should be separated in the free state;
consequently the appearance of this free iodine will be an indication
of the time it takes for the completion of the reaction between the
original substances. If this reaction were instantaneous, the ap-
pearance of iodine would immediately follow the mixing of the two
solutions; but you will soon see that this is not the case. Time is
necessary for the molecular exchange, and in this case, the interval
is sufficiently great to be readily measured by means of an ordinary
watch.

In order to enable you to detect the iodine the moment it is set
free, I shall mix with the solution a little starch paste, which, as
you well know, gives a blue color with free iodine. Perhaps, how-
ever, I had better show you this in the first place. I take here some
starch paste in three beakers; to the first I add some iodic acid,
to the second some hydriodic acid and to the third a solution con-
taining a little free iodine. You see that only the third beaker shows
a decided blue color; iodine in combination not affecting the starch
in this way.

We are now ready to begin with the experiment on speed
of reaction. In the first place, I measure out 25 cc. of iodic
acid solution in one beaker and 25 cc. of sulphuric acid into
another. The iodic acid solution being slightly stronger, we shall
have a little excess of this reagent, to which I add 5 cc. of starch
paste solution and 20 cc. of water. I shall now mix the two solu-

APPENDIX 339

tions rapidly and note the time which elapses until the blue color
sets in.

The experiment is now to be repeated; but I take solutions which
have been warmed in order that the molecules may move more
rapidly. The relative quantities of the total volume remain the
same. You note how much more rapidly the molecular exchange has
taken place.

In order now to show you that space has something to do with
this reaction, I must increase the distances between the molecules in
order that they shall be obliged to traverse more than the previous
distance in order that they may meet one another. How can I do
this ? Simply by distributing them evenly over a larger amount
of water. You will remember that I had employed 25 cc. of each
acid solution, 5 cc. of starch paste and 20 cc. of water, or 75 cc.
in all. If I now preserve all of these measures, excepting that I
substitute 95 cc. of water for the 20, the total bulk will be 150
cc., while the molecules of reacting acids will remain the same. In
this case, then, the speed is very much diminished, although the
time required is not exactly doubled, for there are so many other
questions entering in here, — the reaction is complicated.

In order to produce still another effect, I shall maintain the quan-
tities of this last experiment, but raise the temperature. The time
now approximates that of the first experiment.

Yet another variation may be easily made; I shall increase the
amount of iodic acid while maintaining the amount of sulphurous
acid, and I shall again so arrange that the total volume is 75 cc.
A little explanation is here necessary, inasmuch as I shall take
only 25 cc. of iodic acid solution, but this is made of just double
the strength of the one I originally used. In this case, again, you
will see the speed of reaction is augmented and the time very much
reduced.

The results that I have shown you here involve energy, space, and
time, as well as matter, and I have varied the energy by changing
the temperature, and the space by changing the volume, and you
have seen how time was affected.

BIBLIOGRAPHY OF MORRIS LOEB

Title

Journal

Vol.

Pages

Year

Page
of this
Vol.

1

Ueber die Einwirkung

Ber. d. deutsch.

18

2427-28

1885

169

von Phosgen auf Ae-

ch. Gesch.

thenyldiphenyldiamin

2

Ueber Amidinderivate

Ber. d.ch.Ges.

19

2340-44

1886

171

3

Das Phosgen und seine

Thesis Uni-

1887

177

Abkoemmlinge nebst

vers. of Ber-

einigen Beitraegen zu

lin, March,

deren Kenntnis

1887

4

Das Phosgen und seine

Chem. Cen-

18/1

635-37

1887

Abkoemmlinge nebst

tralbl.(3)

einigen Beitraegen zu

deren Kenntnis

5

Molecular Weight of Io-

J. Chem. Soc.

53

805-12

1888

230

dine in its Solutions

6

Ueber den Molekular-

Z. Physik.

2

606-12

1888

239

zustand des geloesten

Chem.

lods

7

Use of Aniline as an Ab-

J. Chem. Soc.

53

812-14

1888

248

sorbent of Cyanogen

in Gas Analysis

8

Zur Kinetik der in

Z. Physik.

2

948-63

1888

251

Loesung befindlichen

Chem.

Koerper (with W.

Nernst)

9

The Rates of Transfer-

Am. Chem. J.

11

106-21

1889

273

ence and the Conduct-

ing Power of Certain

Silver Salts (with W.

Nernst)

10

The Use of the Gooch

J. Am. Chem.

12

300-01

1890

293

Crucible as a Silver

Soc.

Voltameter

11

Osmotic Pressure and

Am. Chem. J.

12

130-35

1890

21

the Determination of

12

Molecular Weights
The Electrolytic Dis-

Am. Chem. J.

12

506-16

1890

30

sociation - Hypothesis

of Svante Arrhenius

13

Review of Ostwald's

Am. Chem. J.

12

516

1890

45

Grundriss der Allge-

meinen Chemie

14

Is Chemical Action Af-

Am. Chem. J.

13

145-53

1891

295

15

fected by Magnetism ?
Apparatus for the De-

J. Am. Chem.

13

263-64

1891

306

lineation of Curved

Soc.; also

Surfaces in Illustra-

Chem. News

65

220-21

1892

tion of Gases, etc.

APPENDIX

341

Title

Journal

Vol.

Pages

Year

Page
of this
Vol.

16

Laboratory Manual Pre-

New York

—

1-20

1900

321

pared for Students in

Elementary Inorganic

Chemistry at New

York University

17

The Province of a great

Science

16

485-86

1902

46

Endowment for Re-

search

18

Crystallization of Sodi-

J. Am. Chem.

27

1019-20

1905

308

um Iodide from Alco-

Soc.

hols

19

The Vapor Friction of

Science

21

818-819

1905

310

Isomeric Ethers (with

F. S. M. Peterson)

20

Hypothesis of Radiant
Matter

Pop. Science
Monthly

73

52-60

1908

64

21

Report of the Commit-

Reports of

—

1159-70

1909

78

tee to Visit the Chemi-

Committees

. cal Laboratory of Har-

of Harvard

' vard College (with J.

Overseers

Collins Warren, Clif-

ford Richardson, and

James M. Crafts)

22

Conditions Affecting

Science

30

664-68

1909

93

Chemistry in New

York

23

Abstractor (Italian) for

J. Amer.

—

1908-10

Chemical Abstracts

Chem. Soc.

24

Analysis of Some Boliv-

J. Amer.

32

652-53

1910

312

ian Bronzes (with S.

Chem. Soc.

R. Morey)

25

Oliver Wolcott Gibbs

Proc. Amer.

—

69-75

1910

108

Chem. Soc.

26

The Chemists' Club,

The Chemists'

15-17

1910-11

118

New York

Club Year

Book

27

The Chemists' Building

J. Ind. Eng.

3

205-08

1911

121

Chem.

28

Address at Opening of

Met. and

9

177-78

1911

128

Chemists' Building

Chem. Eng.

29

The Eighth Interna-

J. Ind. Eng.

4

556-57

1912

152

tional Congress of Ap-

Chem.

plied Chemistry

30

Coal Tar Colors, pp.

1912 New

5

7^77

1912

132

74-77

Internat.

31

Periodic Law, pp. 593-

Encyc.
1912 New

15

593-97

1912

143

597

Internat.

Encyc.

32

Studies in the Speed of

Proc. 8th Int.

26

601-04

1912

314

Reductions

Cong. App.

Chem.

342

APPENDIX

Title

Journal

Vol.

Pages

Year

Page
of this

Vol.

33

The Fundamental Ideas

This volume

~

1913

3

of Chemistry (Edited

by T. W. R.)

34

Atoms and Molecules

This volume

—

1913

50

(Edited by T. W. R.)

35

Sir Isaac Newton(Edited

This volume

—

—

1913

101

byT. W. R.)

36

Chemistry and Civiliza-

This volume

—

—

1913

156

tion (Edited by T. W.

R.)

INDEX OF NAMES

INDEX OF NAMES

Accademia del Lincei, 153.

Ador, 190, 205.

Albertus Magnus, 162.

American Academy of Arts and Sci-
ences, 115.

American Association for the Advance-
ment of Science, 122, 153.

American Chemical Society, xxiii, 94,
98, 117, 119, 121, 122, 123, 125, 153.

American Electrochemical Society, 98,
121.

American Journal of Science, 111.

American Museum of Natural History,
312.

Anne, Queen, 103.

Aristotle, 52.

Arkwright, 162.

Armstrong, Henry Edward, 40, 41, 42,
43, 71, 205.

Arrhenius, Svante August, 30, 31, 36, 37,
39, 41, 42, 43, 44, 71, 251, 252, 265,
271, 285, 286, 291, 340.

Auwers, K., 229.

Avogadro di Quaregna, Amedeo, 24.

Badische Anilin und Soda Fabrik, 88.

Baeyer, Adolph von, 136, 139.

Basarow, 203, 208.

Baskerville, Charles, vii.

Bauer, 184.

Baxter, Gregory Paul, vii, 78.

Becher, 162.

Beckmann, Ernst, 28.

Becquerel, Jean, 66.

Behla, 190, 206.

Belar, 151.

Bell, 295, 296.

Benedikt, 142.

Bergman, 162.

Berju, 207.

Berlin, University of, 88, 89, 228.

Bernthsen, 220.

Berthelot, Marcellin, 183, 188, 205.

Berthollet, Claude Louis, 8.

Berolzheimer, Daniel D., vii.

Berzelius, Jons Jacob, 8, 113, 181, 205.

Birnbaum, 192, 206.

Black, Joseph, 177.

Bladin, J. A., 175.

Bonhofer, 200.

Bogert, Marston T., xxii.

Bonty, 41, 42, 43.

Bouchardat, F., 179, 198, 207.

Bowman, W., 229.

Boyle, Robert, 24, 162.

Boylstcn Hall, 78, 79 et seq.

Bredig, Georg, 24, 27.

Buchka, 208.

Bunsen, Robert Wilhelm, 106, 120.

Butlerow, 189, 205.

Cahours, 182, 205.

Cannizzaro, Stanislao, 6.

Carius, 221.

Carnegie Institution of Washington, 46,
48, 49.

Carnot, Sadi, 24.

Carstanjen, 184.

Cavendish, 154.

Cazeneuve, 141.

Century Club, 110.

Chandler, Charles F., xxii, 94.

Chandler Hall, 119, 125.

Chaucourtois, de, 144.

Chemical Laboratory of Harvard Col-
lege, xviii, 78, 112.

Chemical Museum, 126.

Chemical Society of London, 112.

Chemische Reichsanstalt, 100.

Chemists' Building, 121-127, 128, 341.

Chemists' Building Company, xviii, 118,
126, 128.

Chemists' Club, The, vii, xviii, xxi, xxii,
94, 118-120, 121, 123, 125, 128, 131,
341.

Ciamician, 195, 206.

Clark, 258, 262, 278, 279.

Clark University, v, vi, xvii.

346

INDEX

Clarke, Frank Wigglesworth, 113.

Claudet, 112.

Claus, Carl Ernst, 116.

Clausius, Rudolf, 30, 229, 252.

College of the City of New York, 112, 119.

College of Physicians and Surgeons, 111,
112.

Collin, 142.

Columbia Grammar School, 111.

Columbia University, 94, 111, 119.

Columbian Exhibition, 152.

Congress of Applied Chemistry, Eighth
International, xix, xxi, 124, 152-154,
341.

Congress of Applied Chemistry, Seventh
International, 93.

Congress of Applied Chemistry, Trien-
nial, 123.

Conrad, 189, 208.

Cooke, Josiah Parsons, 112.

Cooper, James Fenimore, 110.

Copernicus, Nikolaus, 103.

Cornell University, 119.

Couper, R. A., 6.

Cowardins, 184.

Crafts, James M., 92, 190, 192, 199, 200,
205, 341.

Cranston, 181, 205.

Crichton, The Admirable, 3.

Crompton, 41, 42.

Crookes, Sir William, 67, 72, 146, 312.

Daguerre, 157.

Dalton, John, 8, 53, 143.

Dane Hall, 78 et seq.

Davy, Sir Humphry, 177, 180, 205.

Davy, John, 178, 207.

Davy-Faraday Laboratories, 128.

De Clermont, 188, 205.

Delaware College, 112.

Democritus, 53.

Descartes, Rene, 102.

Deville, St. Claire Henri, 5, 116.

Dewar, Sir James, 19, 181, 205.

Dittler, 196, 208.

Doebereiner, 144.

Donders, 25.

Doremus, Ogden, 94.

Dumas, Jean Baptiste, 6, 112, 179, 180,

192, 206.
Dupertius, 207.

Eastman Kodak Company, 90.
Eckenroth, 188, 206.
Edison, Thomas A., 157.
Elbs, 205.

Emmerling, 181, 183, 184, 205.
Escherich, 207.
Ettingshausen, von, 258.

Falck, 196, 208.

Faraday, Michael, 8, 42, 48, 70, 87, 297.

Fenton, 179, 207.

Fischer, Emil, 88.

Fontaine, 188, 205.

Forbes, George Shannon, vii.

Fossati, 296.

Francksen, 207.

Frankfort-on-Main, Physical Associa-
tion of, 249.

Franklin, 295, 297.

Fraunhofer, 106.

Free Academy of New York City, 112.

Fremy, Edmonde, 115, 116.

Friedel, Charles, 187, 190, 192, 199, 200,
205, 206.

Friedlander, 142.

Gabriel, 229.

Galileo, 101, 103, 104, 105.

Gallenberg, Miss Betty. See Mrs. Solo-
mon Loeb.

Gattermann, Ludwig, 206, 208.

Gay-Lussac, Josephe Louis, 8, 24, 254,
275.

Geber, 162.

General Electric Company, 88, 90.

Genth, F. A., 115, 116.

Gerhardt, Charles Frederic, 6.

German Emperor, 88.

Gibbs, George, 111.

Gibbs, Josiah Willard, 111.

Gibbs, Laura, 111.

Gibbs, Wolcott, xvi, xvii, 78, 108-117,
120, 341.

Gibbs (Wolcott) Memorial Laboratory,
xvii, xix, 92.

Girard, Ch., 132, 193, 207.

Glauber, 162.

Gmelin, Leopold, 115.

Goebel, 205.

Goldstein, Eugen, 66.

Gooch, F. A., 211, 293, 340.

INDEX

347

Gradmann, 207.
Graebe, 132, 190, 206.
Green, 142.

Griess, P., 132, 175, 224.
Gronvik, 228.
Guldberg, 36.
Gustavson, 181, 205.
Guthzeit, 189, 208.

Hall, 94.

Hallmann, 201, 208.
Hamburger, H. J., 25, 33.
Hare, H. A., 115.

Harnitz-Harnitzky, 187, 188, 205, 206.
Harvard College, xvi, 110, 341.
Harvard University, xv, xvi, xvii, xviii,

xix, xxiii, 78 et seq., 119.
Havemeyer Laboratory, iii, 94.
Heintz, 206.
Hencke, 208.

Henderson, Lawrence J., 78.
Hendrick, Ellwood, xxi.
Henry, 205.
Henry, J., 24, 157.
Hentschel, 187, 197, 208.
Herschel, Sir William, 51.
Hertz, 87, 157.
Hill, A. E., 313.
Hittorf, 251, 253, 260, 264, 268, 272,

273, 274, 281, 285, 288, 292.
Hoff, J. H. van't, 22, 23, 24, 25, 28, 36,

43, 48, 230, 239.
Hofmann, August W. von, xvi, 5, 6, 109,

120, 127, 132, 169, 174, 179, 181, 193,

194, 195, 197, 204, 205, 207, 210, 217,

220, 222, 225, 228, 248.
Hofmann-Haus, 128.
Hood, J. J., 299, 301, 302.
Horsford, Eben, 5, 112.
Hurst, 142.
Huth, 151.

Jackson, Charles Loring, vii, xvi, 78.
Japan, Imperial University of, 120.
Jaquemin, 248.

Johns Hopkins University, 119.
Julius, 142.

Kaufmann, Walter, 65, 69.
Kekule, August, 6, 187, 188, 206.
Keller, 204, 207, 209.

Kempf, 187, 192, 205, 207.

Kepler, Johann, 103.

Kirchhoff, G., 107.

Kirmis, 253, 274.

Knecht, 142.

Kohler, Elmer P., vii.

Kohlrausch, Friedrich, 32, 43, 251, 252,

253, 258, 264, 265, 267, 268, 269, 285,

286, 287, 288, 289.
Kolbe, Hermann, 182, 205.
Kraut, 187, 206.

Kuhn, Miss Eda. See Mrs. Morris Loeb.
Kuhn, Loeb and Company, xvi.
Kuschel, 253, 274.

Landolt, Hans, 338.

Larmor, Sir Joseph, 67.

Laurent, Auguste, 6, 112.

Lauth, 132.

Lavoisier, 162, 163.

Lawrence Scientific School, 110, 112.

Leblanc, Nicolas, 83, 163.

Le Bon, Gustav, 77.

Le Chatelier, Henri Louis, 111.

Leclanche, 258, 279.

Lefevre, 142.

Leibnitz, 103.

Leipzig, University of, 89, 230.

Lellmann, 200.

Lenard, Philipp, 66.

Lengyel, 181, 183, 205.

Lenz, 253, 274.

Lepsius, 249.

Leuckart, 198, 200.

Leverrier, Urbain Jean Joseph, 105.

Liebermann, 132, 190, 204, 206.

Liebig, Justus, 5, 6, 84.

Lincoln, Abraham, 122.

Lippmann, 35.

Lodge, Sir Oliver J., 40, 43.

Loeb, James, xvii, xix, 92.

Loeb, Morris, bequests, xxii, xxiii, 99;
Berlin University, work at, xvi, xx,
167-229; bibliography, 340-342; birth,
xv ; character, v, xv-xxiii ; charities,
xviii; Chemists' Building, share in,
118; Chemists' Club, presidency of,
xvii, xxi; Clark University, docent-
ship at, xvii; death, xxi; Detur, xvi;
Doctor of Philosophy, xvi, 229; edu-
cation, xvi; elementary manual, 321-

348

INDEX

339; Harvard College, life at, xvi;
Harvard University, Overseers Com-
mittee of, xviii, 78-92; Heidelberg Uni-
versity, work at, xvi, xx; honorable
mention, xvi; honorary degree, xx;
Leipzig University, work at, xvi, xx,
230-247; marriage, xxi; membership
in societies, xix; memorial laboratory
in honor of, 120; music, interest in,
xx ; New York University, professor-
ship at, xvii; researches, v, vi, vii, xx,
167-317; resolutions in appreciation
of, xxi, xxii; Sea Bright, country house
at, xx. See also 259, 273, 338.

Loeb, Mrs. Morris (Eda Kuhn), xxi.

Loeb, Solomon, xv, xviii.

Loeb, Mrs. Solomon [Betty Gallen-
berg], xv, xviii, xx.

Lowenberg, 206.

Lorentz, Hendrik Anton, 64.

Louis XVI, 161.

Lowell, James Russell, 109.

Lucasian Professor of Mathematics, 102.

Lurie, 192, 206.

Magnaghi, 195, 206.

Marcet, 181.

Marconi, Guglielmo, 157.

Marignac, Jean-Charles Galissard de, 116.

Mars, 54.

Massachusetts Institute of Technology,

119.

Mauran, Josephine, 112.
Maxwell, J. Clerk, 64, 87.
Medlock, 206.
Mendeleeff, Dmitri, 14, 41, 42, 43, 144,

149, 151.

Meyer, Lothar, 14, 144, 311.
Meyer, Victor, 207.
Meyerhoffer, 299.
Michaelis, A., 196, 208.
Michelson, A. A., 299.
Michigan, University of, 119.
Michler, W., 193, 194, 198, 200, 204, 207,

209, 217.

Mirandola, Pico della, 3.
Mond, Ludwig, 48, 128.
Morey, S. R., 312, 341.
Miihlhauser, 207.
Murray, John, 177, 178.
Mylius, E., 206.

Nasini, 238, 247.

Natanson, S., 179, 207.

National Academy of Science, 110.

Nemirowsky, 191, 206.

Neptune, 51, 105.

Nernst, Walther, xvi, 34, 35, 38, 40, 43,

44, 251, 253, 264, 270, 273, 275, 291,

340.

Newlands, J., 14, 144, 151.
Newton, Hannah Ayscough, 101.
Newton, Sir Isaac, vi, 101-107, 341.
New York Academy of Sciences, 97.
New York, College of City of, 112, 119.
New York University, vii, xvii, 94, 321,

341.

Nichols, 295, 297.
Nichols, William H., xxii.
Nietzki, 142.
Noyes, Arthur A., 315, 316.

Olberg, 205.

Olympian games, 154.

Ostwald, Wilhelm, xvi, 27, 33, 36, 40, 41,
42, 43, 44, 45, 230, 239, 247, 252, 255,
265, 266, 277, 286, 287, 340.

Pahl, 207.

Paracelsus, 162.

Parthenon, 69.

Pasteur, Louis, 84.

Paterno, 181, 205, 238, 247.

Peligot, 206.

Pennsylvania, University of, 115.

Pennsylvania Railroad, 90.

Peterson, F. S. M., 310, 341.

Pfeffer, 22, 25.

Pickering, S. U., 41, 42, 43, 44.

Planck, Max, 27, 40, 43, 235, 244.

Poiseulle, 311.

Pope, Alexander, 107.

Priestley, 154.

Princeton University, 119.

Proust, 143.

Prout, 67, 143, 144.

Pupin, Michael Idvorsky, 23, 24.

Rammelsberg, Carl Friedrich, 112.
Ramsay, Sir William, 74, 75.
Raoult, F. M., 21, 22, 25, 26, 27, 230,
231, 235, 238, 239, 240, 243, 246, 247.
Rayleigh, Lord (J. W. Strutt), 48, 258.

INDEX

349

Regnault, Victor, 112, 178, 179, 180,

207, 231, 234.
Reicher, 44.
Reichert, E. T., 115.
Reissert, A., 229.
Remsen, Ira, 295, 296.
Richards, Theodore William, 78.
Richardson, 142.

Richardson, Clifford, xxi, 92, 341.
Richter, Jeremiah Benjamin, 143.
Righi, Augusto, 65, 66.
Rilliet, 205.
Roemer, 206.
Rontgen, Wilhelm, 103.
Roese, 185.
Rose, Heinrich, 112.
Rosse, Lord, 106.
Rowland, 295, 296.
Rowley, Walter E., xxi.
Royal Institution, 47.
Royal Society, 102, 152, 154.
Ruhmkorff, 299.
Rumford Medal, 111.
Rumford professorship, 112.
Runge, 132.
Rutherford, Ernest, 66, 72, 75, 76.

Salomon, 193, 206.

Sanger, Charles Robert, 78, 86.

Sarauw, 207.

Schiller, 108.

Schmidt, 201, 208.

Schone, 193, 206.

Schreiner, 185.

Schutzenberger, 181, 182, 205.

Schultz, 141, 142.

Seyewetz, 142.

Siemens, Werner, 127.

Sisley, 142,

Smithsonian Institution, 99, 115.

Snape, 208.

Society of Chemical Industry, 96, 98, 121.

Solvay, 83.

Soxhlet, V. H., 28.

Stacewitz, 187, 206.

Stojentin, 209.

Strassburg, University of, 88, 89.

Thomsen, Julius, 205.
Thomson, Sir Joseph John, 65, 68, 69,
70, 77.

Torrey, Henry Augustus, 78.

Torricelli, 231.

Trinity College, Cambridge, 102.

Union League Club, 110.
United States Sanitary Commission, 110.
United States Steel Corporation, 87.
United States Treasury Department, 130.

Venable, F. P., 151.

Verein zur Hebung der chemischen In-
dustrie, 127.
Villon, 141.

Virginia, University of, 119.
Volhard, J., 254, 275, 308.
Vries, Hugo de, 25, 33, 43, 44.

Waage, 36.
Walker, James, 27.
Warren, J. Collins, 92, 341.
Wartmann, E., 295.
Watt, James, 162.
Weiske, 253, 274.
Werner, A., 116.
Westminster Abbey, 101, 103.
Wharton, Joseph, 109.
Wiedemann, E., 40, 41, 43, 239, 298.
Wiedemann, G., 253, 258, 274.
Wiley, Harvey Washington, 28.
Wilhelm II, German Emperor, 88.
Will, W., 27, 203, 204, 208.
Williamson, Alexander W., 6, 30, 252,

308.

Willm, E., 116, 193, 205, 207, 208.
Wischin, 205, 208.
Wohler, Friedrich, 6.
Wolcott, Oliver, 111.
Wollaston, 157.

World's Chemical Congress, 122.
World's Fair, Chicago, 122.
Woulff, 232, 241.
Wrampelmeyer, 208.
Wroblewski, 207.
Wurtz, Adolf, 6, 191, 192, 199, 206.

Yale University, 119.

Zeeman, Pieter, 65.
Zimmermann, 207.
Zincke, 187, 188, 206.
Zurich, University of, 70.

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