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  SCIENTIFIC CULTURE,
  _AND OTHER ESSAYS_.

  BY
  JOSIAH PARSONS COOKE, LL. D.,
  PROFESSOR OF CHEMISTRY AND MINERALOGY, IN HARVARD COLLEGE.

  _SECOND EDITION; WITH ADDITIONS._

  NEW YORK:
  D. APPLETON AND COMPANY,
  1, 3, AND 5 BOND STREET.
  1885.



  COPYRIGHT, 1881, 1885,
  BY JOSIAH PARSONS COOKE.



  TO
  MY ASSOCIATES
  IN
  THE CHEMICAL LABORATORY
  OF
  HARVARD COLLEGE
  THIS VOLUME
  IS
  AFFECTIONATELY DEDICATED.




PREFACE.


The essays collected in this volume, although written for special
occasions without reference to each other, have all a bearing on the
subject selected as the title of the volume, and are an outcome of a
somewhat large experience in teaching physical science to college
students. Thirty years ago, when the writer began his work at Cambridge,
instruction in the experimental sciences was given in our American
colleges solely by means of lectures and recitations. Chemistry and
Physics were allowed a limited space in the college curriculum as
branches of useful knowledge, but were regarded as wholly subordinate to
the classics and mathematics as a means of education; and as physical
science was then taught, there can be no question that the accepted
opinion was correct. Experimental science can never be made of value as
a means of education unless taught by its own methods, with the one
great aim in view to train the faculties of the mind so as to enable the
educated man to read the Book of Nature for himself.

Since the period just referred to, the example early set at Cambridge of
making the student's own observations in the laboratory or cabinet the
basis of all teaching, either in experimental or natural history
science, has been generally followed. But in most centers of education
the old traditions so far survive that the great end of scientific
culture is lost in attempting to conform even laboratory instruction to
the old academic methods of recitations and examinations. These, as
usually conducted, are simply hindrances in a course of scientific
training, because they are no tests of the only ability or acquirement
which science values, and therefore set before the student a false aim.
To point out this error, and to claim for science teaching its
appropriate methods, was one object of the writer in these essays.

It is, however, too often the case that, in following out our theories
of education, we avoid Scylla only to encounter Charybdis, and so, in
specializing our courses of laboratory instruction, there is great
danger of falling into the mechanical routine of a technical art, and
losing sight of those grand ideas and generalizations which give breadth
and dignity to scientific knowledge. That these great truths are as
important an element of scientific culture as experimental skill, the
author has also endeavored to illustrate, and he has added brief notices
of the lives of two noble men of science which may add force to the
illustrations.




CONTENTS.


                                                                  PAGE
     I.--SCIENTIFIC CULTURE                                          5
    II.--THE NOBILITY OF KNOWLEDGE                                  45
   III.--THE ELEMENTARY TEACHING OF PHYSICAL SCIENCE                71
    IV.--THE RADIOMETER                                             86
     V.--MEMOIR OF THOMAS GRAHAM                                   127
    VI.--MEMOIR OF WILLIAM HALLOWES MILLER                         145
   VII.--WILLIAM BARTON ROGERS                                     160
  VIII.--JEAN-BAPTISTE-ANDRE DUMAS                                 181
    IX.--THE GREEK QUESTION                                        203
     X.--FURTHER REMARKS ON THE GREEK QUESTION                     214
    XI.--SCIENTIFIC CULTURE; ITS SPIRIT, ITS AIM, AND ITS METHODS  227
   XII.--"NOBLESSE OBLIGE"                                         267
  XIII.--THE SPIRITUAL LIFE                                        289




ESSAYS.




I.

SCIENTIFIC CULTURE.

    _An Address delivered July 7, 1875, at the Opening of the Summer
    Courses of Instruction in Chemistry, at Harvard University._


You have come together this morning to begin various elementary courses
of instruction in chemistry and mineralogy. As I have been informed,
most of you are teachers by profession, and your chief object is to
become acquainted with the experimental methods of teaching physical
science, and to gain the advantages in your study which the large
apparatus of this university is capable of affording.

In all this I hope you will not be disappointed. You, as teachers, know
perfectly well that success must depend, first of all, on your own
efforts; but, since the methods of studying Nature are so different from
those with which you are familiar in literary studies, I feel that the
best service I can render, in this introductory address, is to state,
as clearly as I can, the great objects which should be kept in view in
the courses on which you are now entering.

By your very attendance on these courses you have given the strongest
evidence of your appreciation of the value of chemical studies as a part
of the system of education, and let me say, in the first place, that you
have not overvalued their importance. The elementary principles and more
conspicuous facts of chemistry are so intimately associated with the
experience of every-day life, and find such important applications in
the useful arts, that no man at the present day can be regarded as
educated who is ignorant of them. Not to know why the fire burns, or how
the sulphur trade affects the industries of the world, will be regarded,
by the generation of men among whom your pupils will have to win their
places in society, as a greater mark of ignorance than a false quantity
in Latin prosody or a solecism in grammar.

Moreover, I need not tell you that physical science has become a great
power in the world. Indeed, after religion, it is the greatest power of
our modern civilization. Consider how much it has accomplished during
the last century toward increasing the comforts and enlarging the
intellectual vision of mankind. The railroad, the steamship, the
electric telegraph, photography, gaslights, petroleum oils, coal-tar
colors, chlorine bleaching, anaesthesia, are a few of its recent
material gifts to the world; and not only has it made one pair of hands
to do the work of twenty, but it has so improved and facilitated the old
industries that what were luxuries to the fathers of our republic have
become necessities to our generation.

And when, passing from these material fruits, you consider the purely
intellectual triumphs of physical science, such as those which have been
gained with the telescope, the microscope, and the spectroscope, you can
not wonder at the esteem in which these branches of study are held in
this practical age of the world.

Now, these immense results have been gained by the application to the
study of Nature of a method which was so admirably described by Lord
Bacon in his "Novum Organon," and which is now generally called the
experimental method. What we observe in Nature is an orderly succession
of phenomena. The ancients speculated about these phenomena as well as
ourselves, but they contented themselves with speculations, animating
Nature with the products of their wild fancies. Their great master,
Aristotle, has never been excelled in the art of dialectics; but his
method of logic applied to the external world was of very necessity an
utter failure. It is frequently said, in defense of the exclusive study
of the records of ancient learning, that they are the products of
thinking, loving, and hating men, like ourselves, and it is claimed that
the study of science can never rise to the same nobility because it
deals only with lifeless matter. But this is a mere play on words, a
repetition of the error of the old schoolmen.

Physical science is noble because it does deal with thought, and with
the very noblest of all thought. Nature at once manifests and conceals
an Infinite Presence: her methods and orderly successions are the
manifestations of Omnipotent Will; her contrivances and laws the
embodiment of Omniscient Thought. The disciples of Aristotle so signally
failed simply because they could see in Nature only a reflection of
their idle fancies. The followers of Bacon have so gloriously succeeded
because they approached Nature as humble students, and, having first
learned how to question her, have been content to be taught and not
sought to teach. The ancient logic never relieved a moment of pain, or
lifted an ounce of the burden of human misery. The modern logic has made
a very large share of material comfort the common heritage of all
civilized men.

In what, then, does this Baconian system consist? Simply in these
elements: 1. Careful observation of the conditions under which a given
phenomenon occurs; 2. The varying of these conditions by experiments,
and observing the effects produced by the variation. We thus find that
some of the conditions are merely accidental circumstances, having no
necessary connection with the phenomenon, while others are its
invariable antecedent. Having now discovered the true relations of the
phenomenon we are studying, a happy guess, suggested probably by
analogy, furnishes us with a clew to the real causes on which it
depends. We next test our guess by further experiments. If our
hypothesis is true, this or that must follow; and, if in all points the
theory holds, we have discovered the law of which we are in search. If,
however, these necessary inferences are not realized, then we must
abandon our hypothesis, make another guess, and test that in its turn.
Let me illustrate by two well-known examples:

The, of old, universally accepted principle that all living organisms
are propagated by seeds or germs (_omnia ex ovo_) has been seriously
questioned by a modern school of naturalists. Various observers have
maintained that there were conditions under which the lower forms of
organic life were developed independently of all such accessories, but
other, and equally competent, naturalists, who have attempted to
investigate the subject, have obtained conflicting results.

Thus it was observed that certain low forms of life were quite
constantly developed in beef juice that had been carefully prepared and
hermetically sealed in glass flasks, even after these flasks had been
exposed for a long time to the temperature of boiling water. "Here,"
proclaims the new school, "is unmistakable evidence of spontaneous
generation; for, if past experience is any guide, all germs must have
been killed by the boiling water." "No," answer the more cautious
naturalists, "you have not yet proved your point. You have no right to
assume that all germs are killed at this temperature."

The experiments, therefore, were repeated under various conditions and
at different temperatures, but with unsatisfactory results, until
Pasteur, a distinguished French physicist, devised a very simple mode of
testing the question. He reasoned thus: "If, as is generally believed,
the presence of invisible spores in the air is an essential condition of
the development of these lower growths, then their production must bear
some proportion to the abundance of these spores. Near the habitations
of animals and plants, where the spores are known to be in abundance,
the development would be naturally at a maximum, and we should expect
that the growth would diminish in proportion as the microscope indicated
that the spores diminished in the atmosphere."

Accordingly, Pasteur selected a region in the Jura Mountains suitable
for his purpose, and repeated the well-known experiment with beef juice,
first at the inn of a town at the foot of the mountains, and then at
various elevations up to the bare rocks which covered the top of the
ridge, a height of some eight thousand feet. At each point he sealed up
beef juice in a large number of flasks, and watched the result. He found
that while in the town the animalcules were developed in almost all the
flasks, they appeared only in two or three out of a hundred cases where
the flasks had been sealed at the top of the mountain, and to a
proportionate extent in those sealed at the intermediate elevations.
What, now, did these experiments prove? Simply this, that the
development of these organic forms was in direct proportion to the
number of germs in the air. It did not settle the question of
spontaneous generation, but it showed that false conclusions had been
deduced from the experiments which had been cited to prove it.

A still more striking illustration of the same method of questioning
Nature is to be found in the investigation of Sir Humphry Davy, on the
composition of water. The voltaic battery which works our telegraphs was
invented by Volta in 1800; and later, during the same year, it was
discovered in London, by Nicholson and Carlisle, that this remarkable
instrument had the power of decomposing water. These physicists at once
recognized that the chief products of the action of the battery on water
were hydrogen and oxygen gases, thus confirming the results of
Cavendish, who, in 1781, had obtained water by combining these
elementary substances; oxygen having been previously discovered in 1775,
and hydrogen, at least, as early as 1766. It was, however, very soon
also observed that there were always formed by the action of the battery
on water, besides these aeriform products, an alkali and an acid, the
alkali collecting around the negative pole, and the acid around the
positive pole of the electrical combination. In regard to the nature of
this acid and alkali, there was the greatest difference of opinion among
the early experimenters on this subject. Cruickshanks supposed that the
acid was nitrous acid, and the alkali ammonia. Desormes, a French
chemist, attempted to prove that the acid was muriatic acid; while
Brugnatelli asserted that a new and peculiar acid was formed, which he
called the electric acid.

It was in this state of the question that Sir Humphry Davy began his
investigation. From the analogies of chemical science, as well as from
the previous experiments of Cavendish and Lavoisier, he was persuaded
that water consisted solely of oxygen and hydrogen gases, and that the
acid and alkali were merely adventitious products. This opinion was
undoubtedly well founded; but, great disciple of Bacon as he was, Davy
felt that his opinion was worth nothing unless substantiated by
experimental evidence, and accordingly he set himself to work to obtain
the required proof.

In Davy's first experiments the two glass tubes which he used to contain
the water were connected together by an animal membrane, and he found,
on immersing the poles of his battery in their respective tubes, that,
besides the now well-known gases, there were really formed muriatic acid
in one tube, and a fixed alkali in the other. Davy at once, however,
suspected that the acid and alkali came from common salt contained in
the animal membrane, and he therefore rejected this material and
connected the glass tubes by carefully washed cotton fiber, when, on
submitting the water as before to the action of the voltaic current, and
continuing the experiment through a great length of time, no _muriatic_
acid appeared; but he still found that the water in the one tube was
strongly alkaline, and in the other strongly acid, although the acid was
chiefly, at least, nitrous acid. A part of the acid evidently came from
the animal membrane, but not the whole, and the source of the alkali was
as obscure as before.

Davy then made another guess. He knew that alkali was used in the
manufacture of glass; and it occurred to him that the glass of the
tubes, decomposed by the electric current, might be the origin of the
alkali in his experiments. He therefore substituted for the glass tubes
cups of agate, which contains no alkali, and repeated the experiment,
but still the troublesome acid and alkali appeared. Nevertheless, he
said, it is possible that these products may be derived from some
impurities existing in the agate cups, or adhering to them; and so, in
order to make his experiments as refined as possible, he rejected the
agate vessels and procured two conical cups of pure gold, but, on
repeating the experiments, the acid and alkali again appeared.

And now let me ask who is there of us who would not have concluded at
this stage of the inquiry that the acid and alkali were essential
products of the decomposition of water? But not so with Davy. He knew
perfectly well that all the circumstances of his experiments had not
been tested, and until this had been done he had no right to draw such a
conclusion. He next turned to the water he was using. It was distilled
water, which he supposed to be pure, but still, he said, it is possible
that the impurities of the spring-water may be carried over to a slight
extent by the steam in the process of distillation, and may therefore
exist in my distilled water to a sufficient amount to have caused the
difficulty. Accordingly, he evaporated a quart of this water in a silver
dish, and obtained seven-tenths of a grain of dry residue. He then added
this residue to the small amount of water in the gold cones and again
repeated the experiment. The proportion of alkali and acid was sensibly
increased.

You think he has found at last the source of the acid and alkali in the
impurities of the water. So thought Davy, but he was too faithful a
disciple of Bacon to leave this legitimate inference unverified.
Accordingly, he repeatedly distilled the water from a silver alembic
until it left absolutely no residue on evaporation, and then with water
which he knew to be pure, and contained in vessels of gold from which he
knew it could acquire no taint, he still again repeated the already
well-tried experiment. He dipped his test-paper into the vessel
connected with the positive pole, and the water was still decidedly
acid. He dipped the paper into the vessel connected with the negative
pole, and the water was still alkaline.

You might well think that Davy