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A WORD FOR BOYS
AMOS W. PARNHAM, STATE NORMAL SCHOOL, OSWEGO, N. Y. AFTER several years' absence from the He passed along to serve her, and I was n village of H., I returned to it, and left to reflect upon his words. found that time had wrought the great- Since then I have said to more than one est change among those whom I had promising boy, “My young friend, I have left as children. One day I was in the read with pleasure your advertisement, with store of one of the leading merchants, when testimonials, for a place of trust.” When a youth came in. He did his errand and his look of surprise has asked what I meant, went out. Something in his manner led I have said, “Your language, which is free me to ask who he was. My friend, the from slang and profanity, your polite manmerchant, said: “You will be surprised ners, and the good company you keep are when I tell you that he is Mr. M's son.” your advertisement; and your bright eyes, Then he went on to say: "For years I have fair cheeks, pure breath, and elastic step watched the children of this place grow into are your testimonials. They testify that their 'teens.' I have more than once marked you are free from habits that undermine a boy in knee breeches, and told myself health and morals. Now, there is a man that when he was old enough I would try to of wealth who wants you for a place of secure him for one of the departments of trust by and by. The place will demand my business. But as he outgrew his short keen oversight, and only a young man who pants he also outgrew the summer terms has large physical and moral strength will of school, the Sunday school, and parental be able to fill it. But in return for its instruction. He began to smoke cigarettes, demands, it pays well. So, keep your adverto swear, to stand on street corners, to sit tisement where the man of wealth can read on store steps and swap small talk with it every time he meets you. Keep your senseless simpletons. Then I have had to testimonials clean for any one 'whom it may bid good-bye to my boy, and transfer my concern,' and, mark me, boy, by the time hopes to another.” Just then a lady came you want a place the place will want you, from her carriage into the store and asked and you won't have to wear out a pair of my friend to show her some summer silks. shoes to find it.”
I WOULDN'T FRET
Dear little lad with flashing eyes,
The School Teacher's Creed
1 Believe in boys and girls, the men and women of a great to-morrow; that whatsoever the boy soweth the man shall reap. 1 believe in the curse of ignorance, in the efficacy of schools, in the dignity of teaching, in the joy of serving others. 1 Believe in wisdom as revealed in human lives as well as in the pages of a printed book, in lessons taught, not so much by precept as by example, in ability to work with the hands as well as to think with the head, in everything that makes life large and lovely. 1 Believe in beauty in the schoolroom, in the home, in daily life and in out-of-doors. 1 Believe in laughter, in love, in faith, in all ideals and distant hopes that lure us on. 1 Believe that every hour of every day we receive a just reward for all we are and all we do. 1 Believe in the present and its opportunities, in the future and its promises and in the divine joy of living.–Amen.
-EDWIN OSGOOD GROVER.
For the School Room
RADIUM AND RADIOACTIVITY
CHARLES SHEARD, ASSISTANT IN THE DEPARTMENT OF PHYSICS, DARTMOUTH COLLEGE ".
ABOUT a hundred years ago John Dals said to be epoch-making events in science.
ton put the atomic theory of matter As a result of this activity along a comparaupon an experimental basis. Previous to tively new line of research work much that time it had been but speculative and progress is being made toward the solution theoretical. Conclusions drawn from his of the most vexed of all physical questions : work have led scientific men from that day What is the nature and the constitution of to this to believe that matter is of a com- matter? plex nature, being made up of invisible and Some physicists of the present day, notaindivisible, ultimate particles called atoms. bly Ostwald, the celebrated Danish chemist, That which was at first but a mere hypoth- go so far as to say that the atomic theory esis gradually grew into a theory and has must be discarded as useless. This is the fairly assumed the status of a law; for extreme, however. That which has stood these particles of matter have been looked the tests of scientific methods for over a upon as the characterizing features of the century cannot be easily displaced by units of physical division, the molecules. theories and experiments which are yet but The science of chemistry has been founded in the making. "The very fact that not and built upon this theory as its corner- only helium, but oxygen, hydrogen, carbon stone, for it is defined as a classification of dioxide and nitrogen have been found in the laws regulating and governing the com- radium bromide shows how essential it is binations and conduct of the atoms. Thus to the solution of the problem that a fair hydrochloric acid, HCI, has been con- quantity of pure radium should be experi, sidered a compound, the physical unit being mented upon before any satisfactory theory the molecule, the chemical components can be formulated."* Professor. Rutherbeing atoms of hydrogen and chlorine. The ford, in the opening chapter of his book, atoms, of which there are seventy or more says: “While the experimental results have varieties as far as we at present know, have led to the view that the constitution of the given rise to as many different elements. atom itself is very complex, at the same These last are divisions of matter which time they have strongly confirmed the old cannot be further simplified and hence are theory of the discontinuous or atomic strucmolecules composed of the primordial ture of matter. The study of the radioatoms.
active substances and of the discharge of It is not a little interesting that the new electricity through gases has supplied very century should bring in theories and dis- strong experimental evidence in support of coveries which tend to shake our belief in the fundamental ideas of the existing atomic some of the so-called fundamental princi- theory." ples 'of science, among them the atomic Let us now turn our attention to a contheory. The finding of the X-ray, the dis- sideration of the proofs, both theoretical covery of radiation in its various forms and
* Bottone, S., Radium and All About It. the theories of electrons and ions may be
+ Rutherford, E., Radio-activity.
and experimental, given in support of the differences, however, for (1) they are not following statements :
deflected in the slightest degree by a mag1. That the atom, hitherto considered the small- net or charged body and (2) they do not est division of matter, can be broken up into impart negative charges to bodies coming corpuscles.
under their influence. It is generally agreed 2. That these infinitesimally small particles that these rays are ethereal rather than are probably the material out of which all
material in nature. matter is constructed. 3. That radium may be converted into helium;
The question now naturally arises: Do i. e., that the transmutation of elements may take radioactive substances emit rays similar to place and actually has occurred.
cathode or X-rays? At first it was susThe statement has been made that X-rays pected that the radiations from uranium, are emitted by a highly exhausted bulb sub- thorium and radium were similar to X-rays jected to an electrical discharge. But their for the reason that they possessed the power existence is found to be dependent upon of passing through opaque objects and of other rays which are also connected with affecting a photographic plate. When the the discharge. These bear the name of tests were applied which differentiate cathode rays, because they originate at the Roentgen from cathode rays, it was found negative electrode of a tube when in opera that the Becquerel rays emitted were detion.
flected, as shown by the distortion of photoFor several years the nature of cathode graphs and that they had the power of imrays was the subject of much dispute. Some parting negative charges to surrounding thought that they consisted of streams of bodies. It seems therefore that radioactive minute, negatively charged particles shot substances emit rays which are similar to off with enormous velocities from the cathode rays. cathode, while others maintained that they In 1899 Professor Rutherford of Mcwere waves in the ether, similar to light. Gill University discovered that radioactive From proofs furnished by Perrin and J. J. substances gave forth other rays. The Thomson, physicists are now agreed in re- alpha, beta and gamma rays have been disgarding cathode rays as negatively charged tinguished. particles whose mass is only about one one- The alpha rays do not have great penethousandth that of the smallest atom known, trative powers and are stopped by a layer hydrogen.
of air a few millimeters thick. They carry Professor Millikan says:
positive charges of electricity, for they are “Experiments upon cathode rays have proved
found to be deviable in the same direction, conclusively that under some circumstances parti
while under the influence of a magnet, as cles do exist which are smaller than the ordinary particles carrying a positive charge. Their atoms of chemistry. It was the study of cathode mass is approximately twice as great as rays, then, which first sounded the death knell of that of the hydrogen atom. or about the the indivisible atom of our earlier chemistry and prepared for the discoveries, which were soon
size of the atom of helium. to follow, of subatomic transmutations which
The beta rays are the cathode rays given involve the liberation of stored up energies, off by radioactive substances. the very existence of which had never before The gamma rays are gifted with been dreamed of."*
extraordinary penetrative powers. ApAt the time of Roentgen's discovery
parently they are similar to Roentgen rays, many scientists thought that the X-rays if they are not actually the X-rays themwere simply cathode rays which had passed selves. These rays carry no electric through the bulb. There are two distinct
charges, for they are not deviable under the * Popular Science Monthly, April, 1904.
most powerful electromagnets. It is con* Present Problems of Radio-activity, Popular Science Monthly, May, 1905.
jectured that the gamma rays are ethereal pulses.
Whence comes the energy which is represented in the projected particles in the ultimate form of heat and light? This ceaseless emission is not caused by chemical changes. No alteration in the activity of radioactive substances is produced by extremes in heat or cold. Radioactivity seems to be as inherent a property of the atom of radioactive substances as is weight itself. The change. whatever it may be. which is responsible for the expulsion of the various particles must involve a change in the nature of the atom itself.
Professor Rutherford in writing upon this subject, says:
“The evidence, as a whole, is strongly against the theory that the energy is borrowed from external sources and, unless a number of improbable assumptions are made, such a theory is quite inadequate to explain the experimental.facts. On the other hand, the disintegration theory, advanced by Rutherford and Soddy, not only offers a satisfactory explanation of the origin of the energy emitted by the radio-elements, but also accounts for the succession of radioactive bodies. On this theory, a definite, small proportion of the atoms of radioactive matter every second become unstable and break up with explosive violence. * * * * * The energy radiated is, on this view, derived at the expense of the internal energy of the radio-atoms themselves."*
In a paragraph entitled “The Disintegration of the Atom of Radioactive Substances,” Professor Millikan writes:
“Discoveries seem to prove conclusively that the atoms of radioactive substances are slowly undergoing a process of disintegration, this disintegration being indicated, first by the fact that there is a continuous projection from them of particles of matter, the alpha and beta rays; and second, by the fact that we are able to detect the presence of new and unstable types of matter accompanying the phenomena of radioactivity. But just why these atoms are disintegrating and just how these new types of matter are formed must of course be largely a matter of speculation. Nevertheless, discovery has gone far enough to enable us to form a reasonably plausible hypoth
esis as to the probable mechanism of radioactive changes. In presenting this hypothesis the first remarkable fact to be noted is that the three permanently radioactive substances thus far discovered, namely uranium, thorium and radium are the substances whose atoms are the three heaviest atoms known. Thus the atomic weight of uranium is 240, that of thorium 232, that of radium 225, or, according to recent spectroscopic test, 256. There is no other property in which these three substances are alike. In their chemical characteristics they are extremely different. Now, according to our modern mechanical theory of heat, the atoms of all substances are in extremely rapid rotation. It appears therefore that these rapidly rotating systems of heavy atoms not infrequently become unstable and project off a part of their mass. Those particles which are projected first are found to be the alpha particles, and the process of projecting the alpha is the first stage of radioactivity. The mass which is left behind, the uranium X, the thorium X or the emanation, according as the original atom was uranium, thorium or radium, is itself unstable and projects still other particles. The remainder, at least in the case of thorium and radium, is still unstable and another particle is projected. Thus we are able to follow the disintegration of the atoms through four or five successive stages.*
The life history of these substances is tabulated as follows:
Matter Exciting Activity.
Matter Exciting Activity.
Final Product It was the dream of the alchemists of old to convert the baser into the rarer and more valuable elements, particularly gold. Today the transmutation of elements, while not of the specific form searched for by these men of long ago, has actually taken place. In experiments performed by Rutherford and Soddy and later confirmed by
* Recent Discoveries in Radiation and Their Significance. Popular Science Monthly, April, 1904.