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the Ultimate Particles of Gaseous and other Bodies," which he put at the end of his essay read October 21, 1803, and published in November, 1805.

Dalton wrote at this time: "An inquiry into the relative weights of the ultimate particles of bodies is a subject, as far as I know, entirely new; I have lately been prosecuting this inquiry with remarkable success. The principle cannot

be entered upon in this paper; but I shall just subjoin the results as far as they appear to be ascertained by my experiments."

The Atomic

Theory

Dalton was not the first to propose the theory which makes all matter consist of atoms. The Greek and Roman philosophers, wise men of the East in Egypt and India, and such eminent moderns as Sir Isaac Newton and Leibnitz had advocated the theory in some form. Democritus (E. B., Vol. VII. 59) had advanced a form of the theory, not only the earliest, but the most remarkable in the history of science. Among the moderns, Newton had insisted on the existence in all bodies of unbreakable, unwearable, impenetrable particles, each kind of which remains always the same in size, weight, figure and force, so that however compounded, the nature and texture of the compounds are always the same.

Atoms

The distinction of Dalton is that he applied to the existence of atoms a theory which rendered it possible to explain, in accordance with clear and distinct principles, all those changes, an account of which constitutes the science of chemistry. Newton's theory of atoms was one of Dalton's favorite studies, and he very early applied it to the explanation of the diffusion of the particles of water, or aqueous vapor, in the atmosphere, and also to the mingling of the other constituents of the air. He clearly distinguished the particles of aqueous vapor, of oxygen, and of nitrogen, as each having its own individuality, not only of form, but of action, and this brought him to the threshold of his great theory that all bodies, and not familiar gases only, are formed of characteristic atoms.

Among the papers which he left full evidence is found that it was in the study of the constituents of the atmosphere that

Dalton made out a clear view of what atoms are. All atoms of the same kind must necessarily be conceived, he said, to be alike in shape, weight and every other particular, while in different substances the atoms must be different in weight and other characteristics.

Dalton's

Theory

The especially important and altogether new part of Dalton's theory was that which dealt with the relative weights of the ultimate particles of bodies. Here he was making an investigation which, as we have seen that he said, was entirely new, and the success with which he prosecuted it made possible the science of chemistry as it now exists. Dalton fonnd, for example, that every atom of the same element has the same unalterable weight and that the various atoms differ in weight; oxygen, for example, being several times heavier than hydrogen. A remarkable feature of the doctrine of atoms, as Dalton conceived it, appears in what he says of an atom as a hard particle surrounded by an atmosphere of heat. This would seem to mean a space which the hard particle occupied in vibrating. Intensity of vibration in various degrees is thus understood to belong to all atoms.

The discovery of Dalton was brought before the world, not by himself, but by Dr. Thomas Thomson, a professor of chemistry at Glasgow. Dr. Thomson became an ardent disciple of Dalton's doctrine from conversation with him in Manchester. He introduced the new doctrine into his lectures and brought it out in his text-book, published in 1807. Dalton himself published his researches in the "New System of Chemical Philosophy," the first edttion of which was dated May, 1808.

Sir Henry Roscoe remarks, with the highest authority known to modern science, that without the Daltonian atomic theory, modern chemistry would be a chaos, while with it, order reigns supreme, and every apparent and recondite discovery only marks out more distinctly the value and importance of Dalton's work. Dalton's methods of experimentation were indeed rough. He is, in fact, the monumental instance of thinking in science, not slavishly bound to experiment. He was not, as Sir Henry Roscoe says must be admitted, at all great in exact experimental chemistry. He seems

even to have lacked something in either his mind or his hands, without which he could not be a great experimenter. His apparatus and appliances were often of the rudest kind.

But, as Sir Henry Roscoe remarks, Dalton's "results stand out the greatest landmarks in the science of chemistry. His great achievement was that he was the first to introduce the idea of quantity into chemistry. The atomic theory was indeed old, but no one before Dalton used the theory of atoms to explain chemical phenomena. To him is due the glory of placing the science on a firm basis, by showing that the weights of the atoms of the different elements are not identical, but different, and that a combination amongst these elements takes place if more than one compound be formed of the same elements, in simple arithmetical proportion."

In Dalton's day the greatest figure in the world of science was Sir Humphrey Davy. Davy hesitated to accept Dalton's theory. He seems to have rejected it for some years, but to have come at last to something near entire appreciation of its truth and its importance. Dalton himself, on the other hand, not only paid little attention to the work of others, but was sometimes stubbornly indifferent to important conclusions reached by others. Gay-Lussac, for example, made experiments and reached conclusions of discovery which were not only important, but which afforded confirmation of Dalton's atomic theory.

Gay-Lussac found that, under similar circumstances of temperature and pressure, gases combine together in simple proportions by volume; as, for example, two volumes of hydrogen and one volume of oxygen unite to form two volumes of water vapor. Yet Dalton refused to recognize Gay-Lussac's conclusions, in spite of their powerful support of his own view.

He did in this what has been very commonly done in the world of science, and what is still done by men of the largest knowledge and even the highest genius; he made his own confidence in knowledge, and his own consciousness of power in research, the ground of refusal to open his eyes to anything not known by himself. It is quite as common in science as in theology or religion, for knowledge to become so settled, so thoroughly established and so universally accredited as to

make any reopening of important questions extremely difficult, if not quite impossible. Darwinism, for example, has become a creed, many of the adherents of which are as bigoted, as stone-blind to looking any farther or seeing anything else, as any religious dogmatist ever was. Huxley earnestly warned against this long since. He understood the danger

of confidence so extreme as to shut out all new light. Dalton did not. He was wanting somewhat, also, in the broader sympathies commonly created by a liberal education. He took no part in social, much less in political, matters. He was, on the whole, a silent man, and could sometimes be rough and even rude in his manners. His conversational powers were seen at their best when surrounded by a few congenial spirits enjoying a pipe of tobacco. thought it a failure in the character of Sir Humphrey Davy that he didnot smoke.

The

Quaker Man.

cane.

He

He always dressed in the habit of a Quaker-knee breeches, gray stockings and buckled shoes. He wore good broadcloth, with spotless white neckcloth, and usually carried a handsome, gold-headed walkingAbove the average height, robust and muscular, with a broad, expansive head, often compared to that of Newton, he was a singularly impressive figure. When he visited King William at the Court of St. James, and the king asked him how they were getting on in Manchester, Dalton replied: "Well, I don't know-just middlin' I think," and when rallied on the simplicity of this answer to the king, he replied in his broadest Cumberland dialect: "Mebby sae; but what can yan say to sic like fowk."

Honors poured in upon Dalton in later life. At the death of Davy, he was elected one of the eight foreign associates of the French Academy. Berlin, Munich and Moscow equally honored him. At Oxford, in 1832, the degree of D.C.L. was conferred upon him, along with Michael Faraday, David Brewster and Robert Brown. His own estimate of himself appears from what he once said to a young man: "Thou seems to have better talents than I possessed at thy age, but thou may want the thing I had a good share of perseverance." Great hero as he was of science, he was undoubtedly greater still as a hero of self-culture.

CHOLERA IN THE LIGHT OF MEDICAL SCIENCE

NY one who will turn to so good an accessible authority as the article "Cholera," in the Encyclopædia Britannica, may get a clear view of the medical and scientific grounds for distinguishing between two forms of choleraic disease-"two distinct forms of disease," the article says:

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(I) SIMPLE CHOLERA, called also European Cholera, British Cholera, and Summer or Autumn Cholera," and

(II) MALIGNANT CHOLERA, called also Asiatic Cholera, Indian Cholera, Epidemic Cholera, and Algide Cholera ""algide" referring to the collapse and cold stage characteristic of this form of the disease.

The distinction between simple cholera and Asiatic cholera is something like that between typhoid and typhus; only simple cholera may be much more short of malignant than typhoid is short of typhus; and even very severe simple cholera may be, relatively to malignant cholera, much easier to control and cure than severe typhoid.

The distinction between typhoid and typhus was first accurately made out no longer ago than 1836, and not finally established beyond all doubt until Sir William Jenner, at the London feverhospital, in the years 1849-51, made clinical and pathological observations which clearly demonstrated the difference between the two fevers, both in their symptoms and in their origin. Typhoid is bad enough, but typhus is pretty well understood to be the more dreadful and dangerous malady, and if physicians and the press were to make some few cases of typhoid an occasion for a wild cry of Typhus-Plague," the mistake would. discredit and disgrace all concerned in it. The corresponding mistake of taking simple cholera for Asiatic, and wildly crying Asiatic Pestilence," is none the less a scandal and a shame because the newspapers and the medical authorities lend themselves to it.

It is interesting to note of typhus, compared with typhoid, that "while typhus is a disease of overcrowding and poverty, typhoid may occur where such conditions are entirely excluded." In the same way much that is said of cholera as a "filth

disease" applies to malignant cholera, and does not in the same way apply to simple cholera. And as in the case of typhus, the origin of the disease is from offensive conditions of life, yet the typhus infection will no less strike the clean and wholesome if they come in contact with it, just so in the case of cholera; although its infection is much easier to escape, yet it may strike the clean as well as the unclean if they are sufficiently exposed. It is from the author of the article on cholera referred to above that we quote the comparison between typhus and typhoid.

Another fact of typhus, as a disease more dangerous than simple cholera, is its violently infective character, and yet the comparative security of those who handle it if they know how to use proper The author just quoted says:

care.

"In most large cities limited outbursts of the disease occur from time to time, under the conditions of overcrowding and poverty [unclean overcrowding, it should be said, filthy habits of person, nasty bedding, bad food, as rotten fruit and tainted meat, or the variously terrible diet of starvation, which makes hunger-typhus one of its worst types], although the increased facilities for recognizing such outbreaks, and for the prompt isolation or removal of infected persons to hospitals, operate in general effectually to prevent any extensive spread of the fever. The disease appears to be communicated by the exhalations given off from the bodies of those suffering from the fever, and those most closely in contact with the sick are most apt to suffer. This is shown by the frequency with which nurses and physicians take typhus from cases under their care [where proper precautions are not practicable]. As in all infectious maladies, there is often observed in typhus a marked proclivity to suffer in the case of individuals, and in such instances very slight exposure to the contagion may convey the disease. Typhus is highly contagious throughout its whole course and even in the early period of convalescence. The contagion, however, is rendered less active by the access of fresh air; hence, this fever rarely spreads in well-aired rooms, or houses

where cases of the disease are under treatment. Although not unknown in warm countries, it has most frequently prevailed in temperate or cold climates."

In the case of cholera, whether simple or malignant, there is no infection from the persons of the sick; not even from their discharges, or soiled clothing, nor from the dead, provided always that no needless exposure is ventured, and that the discharges and soiled clothing are at

once disposed of, and on no account allowed to stand and ferment; for by standing and fermenting they become. dangerous from the exhalations of an infectious character which they will give off.

It is a singular fact that the existence of typhus, with its much greater danger of infection from the persons of the sick, will not be used by the press to create a scare, while at the mere name of cholera of the common and simple character, which involves no danger whatever of infection from the sick, there may be a wild cry of "Asiatic Plague." This is because experience has made typhus familiar, and people have learned to deal with it properly. They might equally learn to take cholera sensibly, not only without panic, but without any fear of the presence of the sick, or of the dead. Not even in malignant cholera is there any danger of contagion from the sick or from the dead. The great and most urgent necessity is for disposal of the discharges promptly and effectually. One of the best authorities, Dr. Charles Creighton, in the Encyclopædia Britannica article on quarantine, says of "Principles of Quarantine Against Cholera":

"The peculiar dangers of cholera-diffusion arise from the vomited and purged matters which are characteristic of the malady. Under certain circumstances the discharges of the sick are infective; they are probably not infective as they come from the body; but even minute quantities of the choleraic matters, if they have fermented in the ground, or in boxes and bundles of foul linen, bedding or clothes, may exhale a virus which is often suddenly prostrating in its action. Thus every person with cholera, or even with choleraic diarrhoea, in times of epidemic is a source whence many more may be poisoned [not from the persons themselves, but from the choleraic matters vomited or purged and not taken care of at once]. When the choleraic matters percolate into wells or reservoirs the poisoning may be on a great scale."

The fact of infection, where it takes place at all, by means of poisonous exhalations, or by choleraic matters contaminating water, is of peculiar significance as showing a cholera-cause other than microbes. The very common references to a cholera-microbe are calculated to mislead. They are not according to fact. Granting the existence of microbes, which, though the merest invisible microscopic things, form a parcel of cholera-poison, and that water contaminated

with these will cause cholera, it is yet next to impossible to infect with these except by means of contaminated water; and the common talk, as if the microbes were able to get out of the choleraic fluids, to fly about, and to alight on people and on their food, and so get into them, is nearly or quite pure imagination and utter foolishness. It is equally imaginative and foolish to suppose that a microbe too small to be visible, and forming a parcel of cholera-poison so minute as to be revealed only by the microscope, operates in a violent attack of cholera by breeding other microbes, which make cholera-poison, and so cause the cholera sickness. It is far more probable that when cholera-poison in considerable amount is taken in with the breath, or in water, and perhaps in both ways, some law of the system makes up more or less of it into microbe-parcels, which are thus results of the presence of a poison, all or most of which has been taken into the system in the form of a volatile poison, and not in the form of microbes. At any rate an immense body of evidence goes to show that the general and ordinary form of infective poison is that of a miasmatic exhalation, a volatile poison in the air, which may be, and commonly is, taken with the breath.

The thing most important to note about typhus is the miasmatic exhalations from the persons of the sick and their violently infective character. It is not enough noted that persons may be a source of these typhus exhalations before they are sick and without being sick, owing to an excessively foul condition into which they have got and which they have become habituated to. An Egyptian convict-ship on which there was no sickness brought an epidemic of typhus to Liverpool in 1861, clean people taking the infection by contact with the well from the ship. In February of 1892 the New York health authorities made a most deplorable exhibition of ignorance of the generation of typhus in the case of a lot of Russian Hebrews who arrived in the Massilia, January 30, after a voyage of twenty-eight days, without any death or any sickness from typhus, but some of whom came down with typhus February 11. We cannot fully deal with the matter here, but will merely state the simple fact that on the first of March the health authorities had 102 persons packed into one lodging

house, out of which they had sent fiftythree typhus cases, all developed in the house. At this date the place was cleared and the plague checked. A more scandalous making of a poison-den could not have been contrived. A reporter and two policemen, who orce or twice entered the house, sickened and died. From February 11 to March 5 there had been 137 cases and nine deaths, nearly all of them due to crowding the suspects into lodging-houses in the city. Yet even then, when proper measures were taken, the sickness was checked, and no panic was raised meanwhile, although some effort in that direction was made.

The point we wish to make plain here is the comparative safety of the public in presence of so infective a disease as typhus. Serious as the infection may be, its character can be greatly modified by proper care. Dr. Murchison said: "If a patient be placed in a large, well-ventilated apartment, the attendants incur little risk, and the other residents of the same house none whatever." Dr. Austin Flint held the same view, although his very long experience covered some years of prevalence of the disease in one of the hospitals, the condition of which could not be made properly wholesome. Wherever entire cleanliness and good ventilation are secured, typhus cases in a hospital do not create danger for either the attendants, the physicians or students inspecting the sick. In the case of the Russian Hebrews in New York, whose systems had been breeding typhus-poison from their starvation diet in Russia, their hardships of travel and their voyage of twenty-eight days, shut up in stormy weather in the steerage of a ship, the very great probability is that if, in a place securing abundance of good air, they had been thoroughly cleansed with warm alkaline bathing, their garments steamed and cleaned, or replaced with new of proper warmth, and a good diet of hot soups, nice bread and some fruit been given them, not a single case of typhus would have been developed.

On the other hand typhus can be developed without any contact of the victims with infection. The chemistry of the healthy system is all the time producing a variety of poisons, especially in the intestines, but to a degree all through the system. In healthy persons, under wholesome conditions, these poisons are

A

excreted by organs of excretion and by the lungs and the pores of the skin. principal office of a good liver is that of stopping poisons in the blood brought to it by what is known as the portal vein. Some it destroys and some it stops and sends off in the bile to be cast out by the bowels. Dr. T. Lauder Brunton says, in a recent volume of lectures entitled "An Introduction to Modern Therapeutics":

"The knowledge which we have gained during the last few years regarding the poisonous properties of some albuminous substances, and of the products which albumen yields when decomposed, makes it, as Mr. Darwin once said to me, a wonder that we are all alive, considering how many poisonous substances are constantly formed in the intestines. Indeed, one can hardly see how life would continue long were it not that the liver has a position and function like the gatekeeper of a castle in time of war, inspecting all comers, and turning back those that are dangerous. It possesses a twofold power to prevent poisons entering the portal vein from passing into the general circulation, for it turns back some and destroys others. Some are simply arrested and excreted by the bile, and finally ejected from the body. Some it has the power of actually destroying, or, at any rate, converting them into non-poisonous compounds. Organic poisons appear to have their activity lessened in the liver by combination with glycogen. Leucomaines [alkaloid poisons] are formed in the tissues generally, and an increase of glycogen in the blood [from food, as milk, supplying it] may combine with poisonous products in the nerves and muscles, preventing them from exerting a poisonous action, and thus removing weakness, languor, or

tremor due to them."

The "volatile poisons excreted from the lungs and skin," says Dr. Brunton, help to cause the bad effect of foul air. They will, in fact, though very subtle and volatile, and in very small quantity, rapidly make the air of a close room foul. They become also a deadly virus in the sweat and grime accumulated on the skin and the clothing of the unclean; and a great number of facts prove that when these poisons are retained in the system, by any failure of excretion or by excess of production, or are taken back into the system with the breath, the results may be of the worst typhus, or at least typhoid, character. In the case of the Black Hole of Calcutta, where 146 persons were confined in a room twenty feet square, with only two small windows for air, 126 died over night, and of the twenty-three who remained alive, says Dr. B. W. Richardson, "nearly the whole suffered afterward from what was called putrid typhus,

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