Chapter VI: Part 6

The period between the ages of five and ten years is an important one in the child's life. It is the time when the "let-alone" plan of education is of most value, for the reason that nearly all our educational devices beyond the kindergarten are more or less attempts to make men and women out of children. If the child at this age must be put into the harness of an educational system, his course of study will not be impoverished by the omission of reading and writing. To teach him to speak and to listen, to observe and to remember, to know something of the world around him, and instinctively to do the right thing, will furnish more than enough material for the most ambitious elementary school curriculum.

FOOTNOTE:

[45] See the article on Courses of Study in the Elementary Schools of the United States, by T. R. Crosswell, Pedagogical Seminary, April, 1897.

SOILS AND FERTILIZERS.[46]

BY CHARLES MINOR BLACKFORD, JR., M. D.

The word "soil" is used in several arts and sciences to denote the material from which something derives nourishment. The meat broths and jellies on which bacteria are grown are soils for them, as the earth of a field is a soil for the ordinary farm crops; but in general we mean by soils the various mixtures of mineral and organic substances that make up the surface of the earth.

The object of this paper is to show as briefly as possible the way it was formed, of what it is composed, the manner in which it nourishes plants, and the rules that should guide us in replenishing its nutritious matter when exhausted. So broad a field can be but lightly touched, and the effort will be to give only hints from which rules for specific cases may be deduced.

When a sample of ordinary fertile soil is analyzed, it is found to consist of a number of minerals, of carbon, nitrogen, and phosphorus in various combinations, water, and certain other ingredients dependent on the locality. Among the minerals the most important are potassium, sodium, lime, iron, and silicon, and the history of these is of the greatest interest.

Scientific students are generally agreed that the surface of the earth is but a shell inclosing a liquid, or at all events a highly heated interior. Originally the whole mass was fluid, but the surface has cooled more rapidly than the interior, and so a firm crust has been formed. As the central mass cooled, it contracted, and the crust became wrinkled and folded, as does the skin of an apple as its pulp dries, and, by this folding, great ridges were thrown up in some places and vast depressions formed in others. When the crust became cool enough for water to remain on it, most of the depressions were filled by it, and the "dry land appeared," not only on the crests of the ridges, but on the elevated plateaus about them, and thus oceans and continents were formed.

Had one of us seen the earth at that time he would have been loath to select it as a residence. Rugged, rocky ranges of precipitous mountains surrounded by stretches of naked rock made the landscape. Dense clouds from the tepid oceans dashed against the icy peaks, and torrents of water rushed back to the sea. Where the slopes permitted, the glaciers spread over wide areas, for no vegetation checked the rapid radiation of heat, and night brought bitter cold. The crust waved and fluctuated over the liquid interior as does thin ice under a daring skater, and as it fell the sea rushed over the land, only to flow elsewhere as the depressed area rose again. The freezing and thawing and the effects of wind and water in time produced a change. The rocks were riven and broken to powder, their nearly vertical slopes became less steep, and instead of bare rock the earth showed dreary morasses and stretches of sand.

Over these marshes vegetation began to thrive. In the sea there lived then, as now, a teeming population, animal, vegetable, and living beings that can with difficulty be assigned to either of these classes. Each of them, however, contained carbon, and many had built lime, phosphorus, nitrogen, and other valuable substances into their bodies. Where food was abundant these grew in vast numbers, and though many are infinitely small singly, their aggregate mass is enormous. Among the tiny organisms is one called the _Globigerina_, a being so small as to require a microscope to study it, but in the past, as now, growing in great numbers in the sea. The animal is soft and jellylike, but it forms an outside skeleton of shell of carbonate of calcium or chalk, a structure that protects it living, but entombs it dead. When death comes, the little _Globigerina_ sinks to the bottom, and its tiny shell helps to cover the sea floor.

In the days of long ago these lived as now, and when some convulsion of Nature lifted the bottom of prehistoric seas, the _Globigerina_ ooze was lifted as well, and thus the "limestone" formed. In our land a bed of this kind extends from Alabama to Newfoundland; thence, as the "telegraphic plateau," it passes under the Atlantic, rising into the chalk downs and cliffs of England; then, again dipping under the sea, it passes through Europe, and finally furnishes the marble quarries of Greece. Heat, water, and chemical action give a ceaseless variety to the forms of the limestone, but wherever found it shows the former seat of an ocean.

As soon as the "ooze" was lifted from below the sea it began to change. Some has been exposed to heat and has crystallized into marble, but for our purposes the most interesting changes have been wrought by water. Chalk, limestone, and marble--for these are chemically the same--are almost insoluble in pure water. But water is rarely pure; it dissolves many things, and among them the carbonic-oxide gas that every fire, every animal, every decaying scrap of wood is pouring into the atmosphere. The rain, charged with this gas, dissolves the limestone, but when the gas escapes the lime falls, as you know happens when "hard" water is boiled, for the heat drives off the gas. By this solution, however, the lime is scattered widely through the soil, and is rarely lacking in untilled earth.

Besides lime, phosphorus is necessary in a good soil. This is widely spread in Nature, but its great reservoir is the ocean, that boundless mine of wealth. Many marine animals have the power of building it into their tissues, and the shells of oysters and other mollusks, the bones of nearly all animals, terrestrial and marine, and parts of other organisms, are composed of phosphates to a greater or less degree. In the ceaseless changes of level the primal oyster beds and coral reefs are raised to the surface or far above it, and the slow action of time begins to tear down the deposits and spread them wide-cast. Since that far-off time "in the beginning" no new matter has been put on earth save the small amounts of the meteorites, and the economy of Nature can allow not one atom to lie in idleness, but calls on each one to play its part ceaselessly, "without haste and without rest." A certain amount of a substance is disseminated through the earth; by rains it is washed into the streams, and thence to the sea. Here plants or animals eagerly await it, and by means of them it is again restored to the land, to begin again its endless round.

The metals most necessary for plant life are potassium, sodium, and iron; indeed, the very name of the first shows its importance. If the ashes which contain all the mineral constituents of plants be put in a vessel and water poured on them, a solution of lye will percolate through the mass. The word lye is an abbreviation for alkali, and when chemistry became sufficiently advanced, a metal was discovered in this lye to which the name potassium--i. e., potash-metal--was given. If seaweeds be burned and leeched in the same way we can obtain from the lye another metal, sodium, that is much like potassium, and that is one of the most widely spread substances on earth as its chloride, or common salt.

Potassium and sodium enter into the composition of many rocks, and as these become eroded by weather they are scattered through the soil, whence their salts are extracted by rootlets and enter into the formation of vegetable tissue.

Behind these stands iron. The green coloring matter of plants is a very complex substance known as chlorophyll, the duty of which is to take carbonic oxide from the air, utilize the carbon, and restore the oxygen. Iron enters into the composition of chlorophyll, and to it is due the brown color of dead leaves. This metal is well-nigh universal, all the reds and browns in soils and rocks being made by it, and so it is rarely lacking anywhere.

So much for the metals in soils; but, important as they are, plants can not live on them alone. Among the nonmetallic bodies phosphorus stands high among essentials, and for it we are indebted to the sea and the interior of the earth. Many living creatures extract phosphorus from the sea water--combine it chiefly with lime, and use the phosphate for making skeletons or shells, as the case may be. After the death of the possessors the bones or shells sink to the bottom, as do the _Globigerina_, and in time are either lifted up, as were the limestones, and form "phosphate beds" like those of Georgia and Florida, or are dredged up and ground into powder with bones of land animals.

Much of the matter forced up from the interior of the earth contains phosphorus; indeed, it is the bane of Southern iron ores; but though iron masters dread it, farmers welcome it, as the rains and frosts crumble the phosphatic rocks and add them to the mass of _débris_ that forms our soil.

Now let us take a test tube and put into it lime, potash, soda, iron, silicon, or sand, and phosphorus, add to it a grain of corn, and watch results. Under suitable conditions of warmth and moisture the grain will sprout, but when the store of food laid up in it is exhausted our little plant will die. It is obvious that something else is needed for a soil, and analysis shows that it is nitrogen, the gas that forms nearly four fifths of our atmosphere--a gas useless, as such, to animals, but essential to plants. Nitrogen is abundant in Nature. Besides being nearly four fifths of the air, it forms twenty-two per cent of nitric acid, forty-five per cent of saltpeter or niter, eighty-two per cent of ammonia, and about twenty-five per cent of sal ammoniac. Plants can not use nitrogen in its pure form, but one or another of these forms will be found in the soil, whence it may be extracted.

Now we have the chief articles of plant food, and it is necessary to know how they are to be used. A plant usually consists of two parts, one that appears above ground, bearing branches, twigs, and leaves, and another that remains below ground. It is this latter that concerns us now, and it is worth study. This lower part consists of a number of twigs called rhizomes, from which proceed a vast number of fine, threadlike rootlets, and these are the mouths of the plant, through which it draws nourishment from the earth about it.

Before any living thing can use nourishment from without, it must be dissolved, and this solution requires much preparation at times. Men, and other animals with a wide range of food stuffs, effect this by the secretions of the digestive organs; but most plants have no digestive apparatus, strictly speaking, and were they supplied with an abundance of the foods they most need, they would starve unless the food were in a suitable state for absorption.

The way in which Nature effects this solution is the key to many of her secrets, and it has been understood only within the past few years. If we have a piece of meat freshly taken from an animal we find it firm, coherent, and almost odorless. If it be put into a warm, moist chamber for a few days a great change comes over it, and it becomes soft, offensive in odor, and liable to fall to pieces. We say that it is rotten or putrid. If a bit of it be put under a microscope, it is seen to be teeming with bacteria, and these are responsible for the decay. Now, if a specimen of earth be examined, we find that it contains bacteria, that attack all kinds of organic matter, tearing it to pieces to get their food, and making many different things out of what is left. There is one sort of ferment that grows in apple juice and splits the sugar into alcohol and carbonic acid, forming "hard cider," and if the fermentation stops at this point the well-known drink results. However, there is another ferment called "mother of vinegar" that may get in, and, if so, a different kind of fermentation is started that forms acetic acid instead of alcohol; or the bacteria of decomposition may come in and the whole go back to its elements.

There is a wonderful provision of Nature shown in these stages. The bacteria--the organisms that produce decay--can not live in a strong sugar solution, but the ferments, like common yeast, can live in it, and they split the sugar into alcohol, carbonic oxide, and other things. In these another set can live, and when the first have died of starvation or from the alcohol they form, the second set step in and turn the weak alcohol into acetic acid. Acetic acid is a preserving agent, as our sour pickles show, but if it is not too strong there are some organisms that can live in it, and the whole process ends in decay. Now, it should be noticed that each of these organisms paves the way for the next by converting an unsuitable food stuff into a suitable one.

This familiar example indicates the lines on which Nature works. It is the same everywhere, and shows the advantage of specialization, of allowing some one with peculiar facilities for performing an act to do that exclusively, that others may profit by his skill. So long as each man sought and killed his food, cooked his meals, made his own clothing, weapons, and implements--in a word, lived alone--advance was impossible. It was only when he who was most skillful with the needle made garments for the hunter in exchange for a haunch of venison, that the hunter could practice marksmanship, and the tailor design a new cut for the mantle with which the warrior might dazzle the daughter of the arrow maker. It is the same in Nature. Some organisms possess powers of elaborating certain materials of which others are quick to avail themselves. Plants can manufacture starch, an article needed by animals, but of which their own capacity, so far as producing it is concerned, is very limited, and thus animals find it advantageous to avail themselves of these stores instead of taxing their own resources. Similarly, plants need the organic matters of the animal bodies, and wise agriculture supplies carbon, nitrogen, and other articles of food in the shape of animal and vegetable refuse. But this matter requires digestion; it must be made soluble before it can be absorbed, and but few plants can effect this solution unaided. The "Venus's flytrap," the sundew, the wonderful "carrion plant," and others, are equipped with elaborate apparatus by which they are enabled to capture, kill, and literally digest the insects that supply them with nitrogeneous food, but these are exceptional cases. Nature usually employs other agents.

The action of bacteria in causing decay has been said to be in general similar to fermentation--that it is effected by the bacteria in seeking their food. If oxygen be abundant, putrefaction occurs; if it be scant or absent, then fermentation takes place, for the tiny organisms require oxygen, and, if the air fails them, they pull to pieces the organic matters near them to obtain it. In doing this they get the nitrogen into such shape that the plants can use it, and thus digest their food for them. All organic matter contains carbon, hydrogen, and oxygen as a general rule, and to these are often united phosphorus, sulphur, nitrogen, and others, making very complex arrangements, veritable houses of cards, in fact, only held together by the strange power of life. When a leaf falls or a bird dies, some of these combinations are broken, and then the bacteria and other lowly organisms have full sway, for living matter is impregnable to all save a few of them. As oxygen or something else is taken out of the complex molecules, the compound falls to pieces, but as in the kaleidoscope the bits of colored glass tumble into endless varieties of symmetrical figures, so do the atoms fall into new combinations. If the keystone of an arch be removed, the stones fall apart; but atoms, unlike bricks or stones, can not stand alone as a rule; they must be united to something, and so, as soon as old associations are dissolved, new ones are formed. These new ones are those needed by plants, and thus is plant food digested.

The term "plant food" has been frequently used, and should now be distinctly explained, for merely stating the chemical elements is not describing the food. When a physician tells a nurse to feed a patient he does not order so much carbon, nitrogen, phosphorus, and the like, but specifies a soup, certain vegetables, and so on, detailing every particular; and the same should be done for vegetable invalids.

In medical practice a condition is recognized that is called scurvy. It is not exactly starvation, but is produced by lack of some food materials usually supplied by fresh vegetables. If scurvy appears at sea, no amount of meat, bread, cakes, or pastry will stop it; vegetables, and they only, will stay it. Sometimes a similar condition prevails among crops: some ingredient in a soil is lacking, and the others may be supplied indefinitely without giving the desired relief. To this may be attributed much of the fault found with fertilizers; for if the soil does not need a particular compound it is useless to apply it, and an excellent fertilizer is often blamed for not producing a crop on land already overstocked with it and crying for something else.

Let us suppose a field on which cotton has been grown for many successive years until it has become exhausted. Analysis shows that a crop yielding one hundred pounds of lint to the acre removes from the soil:

Nitrogen 20.71 pounds;
Phosphoric acid 8.17 "
Potash 13.06 "
Lime 12.60 "
Magnesia 4.75 "
-----
Total 59.29 "

The weight of the whole crop from which these figures were taken was eight hundred and forty-seven pounds, so that cotton exhausts land less than any staple crop, if the roots, stems, leaves, etc., be turned under and only the lint and seed be removed. Of these the lint (one hundred pounds) takes 1.17 pound from the soil, and the seed 13.89 pounds, making 15.06 pounds net loss.[47] But ignoring returns that may be made in the shape of cotton-seed meal, etc., and lime, with which our soils are abundantly supplied, we see that nitrogen, phosphoric acid, and potash have been removed. Suppose the owner puts bone meal on his exhausted land: the phosphoric acid in the bone will supply one need, and an improvement results. On the strength of this, bone meal will be loaded into the soil again, and let us suppose the deficit not yet made up, the crop again shows improvement. Now, phosphoric acid abounds in the soil, though the deficiency in nitrogen and potash has become steadily greater; so, when the customary bone meal is applied, the crop falls back, because the plants are starving for potash and nitrogen. They are like scurvy-smitten sailors, but many thoughtless farmers would attribute the decline to the maker of the bone meal, and say that its quality was not so high as formerly--an opinion similar to that of a sea captain who would ascribe to the poor quality of salt beef an outbreak of scurvy on his vessel.

As crops of any description extract potash, nitrogen, and phosphoric acid from soils, the question how they are to be replaced is an important matter, and its answer may be most readily found by studying Nature's methods. In parts of the Old World there are fields that are fertile in the extreme after thousands of years of tillage, and it is apparent that mere cultivation does not prove injurious. The tropical forests have something growing wherever a plant can find foothold--a population in which the struggle for food is secondary to that for light and air, and yet the soil supporting this vegetation is marvelously rich. Every leaf that falls remains where it fell until in the warm, moist, half-lighted forest it becomes a little heap of mold. The bacteria of decomposition require warmth and moisture for their life; light is deleterious to them, but they thrive in the dense shade of the jungle. The tangled web of roots, weeds, and vines retains the rainfall, retarding evaporation, and preventing both droughts and freshets. Receiving dead and broken leaves, boughs, and other vegetable products, and spared the washing of violent torrents, the forest is inestimably fertile.

On a smaller scale this goes on universally. The annual weeds, deciduous leaves, and such matter, fall prey to molds and bacteria, by which they are made soluble. Snows and rains bear the products into the soil, and there other bacteria, clustering around the roots, form the acids needed to complete solution. Every one knows that "well-rotted" manure is better than that which is fresh, and many wonder at this, but the reason is apparent. In feeding delicate patients, physicians often prescribe predigested foods or the digestive ferments to aid enfeebled assimilation; and similarly the manures that have been thoroughly acted on by bacteria, or containing those capable of producing the matters that plants need, are of most value for nourishing vegetation.

In producing an article of any sort, the cheapness and ease with which it can be made is largely dependent on the shape in which the raw material reaches the factory. If a foundry can procure iron that needs only to be melted and cast, the owner can fill his orders more readily than would be possible if he had to reduce the metal from the ore; and Nature uses this principle over and over again. The importance of nitrogen to plants and its abundance in Nature have been mentioned, but it has also been said that plants can not use it directly, as most animals do with oxygen. The tiny bacteria intervene, and this they do in two ways: first, by causing decay of animal or vegetable matter containing nitrogen, and by this decay producing substances that plants can absorb; and, secondly, by producing little nodules or "tubercles" on the rootlets, through which the plant can take up nitrogen.[48] Now, when a plant is sated with nitrogen, it ceases to form these tubercles, and their formation is a sure sign that the plant is craving this article of food. When it is supplied, and its own life is ended, these form reservoirs from which other plants may be supplied, as new castings may be made from broken wheels. The great value of "green manuring" depends on the store of available nitrogen so laid up, but it is open to failure in one direction. The liability of fermentation to go to the acid stage from contamination with acid-forming ferments has been mentioned, an accident the possibility of which is impressed on us from time to time by sour bread; and similarly the organic matter turned under may undergo acid fermentation, rendering the ground "sour" and unfit for cultivation.

The limits of this paper forbid the consideration of special fertilizers, but from the general principles laid down the rules for any special case may be deduced. A soil should contain a sufficient amount of potash, soda, lime, iron, and a few other minerals; phosphoric acid, nitrogen, organic matter, and, for some special crops, some other ingredients may be needed. When the soil needs renewing, there are two ways of accomplishing it. One way is to guess at what is needed; to buy fertilizers at high prices, without inquiring whether the soil needs the substances in that particular brand or not. Though very common, this is not a good plan. It is as though a physician were to give a patient any drug that was convenient, without inquiring into the disorder or the needs of the system, and it is followed by much the same result. That acid phosphate gave Farmer A a good crop, is no reason that Farmer B's land is also deficient in phosphorus. The same reasoning would teach that a heart stimulant that rouses a patient from shock would benefit one in danger of apoplexy, where the least increase in heart force might be fatal. A physician using such reasoning as the basis of his practice would not be considered a master of his art; and were he to attribute the fatal outcome of his logic to the poor quality of his stimulant, he would display criminal ignorance of drugs as well as disease; yet it is very common to see farmers put guano on a soil begging for potash, and then heap execration on the head of the dealer who sold the guano when the crop failed. To revert to a simile used above, a captain must not blame the salt pork for scurvy.

The other way to buy and use fertilizers is to ascertain what a certain crop needs; then find out whether these be in the soil, and to what extent. With these data the deficiency may be made good without the wasteful cost of the former method. State and Federal Departments of Agriculture furnish their aid freely and gladly, and already the signs are seen of the day when agriculture will take its place among the semiexact sciences, and the present haphazard methods will become obsolete.

FOOTNOTES:

[46] An address delivered before the Richmond County (Georgia) Agricultural Society, on February 19, 1898.

[47] United States Department of Agriculture. Farmers' Bulletin, No. 48.

[48] Leguminous Plants for Green Manuring and for Feeding. E. W. Allen, Ph. D. United States Department of Agriculture. Farmers' Bulletin, No. 16.

SKETCH OF AUGUST KEKULÉ.

"This news," said Herr H. Landrelt, president, announcing Kekulé's death in the German Chemical Society at Berlin, "will be received with sorrow not only by our society but by the whole chemical world. Science has again lost one of its greatest representatives, one of those extremely rare spirits who were called upon to found a new epoch in it and push it mightily forward."

FRIEDRICH AUGUST KEKULÉ was born at Darmstadt, September 7, 1829, and died, after a long illness, at Bonn, July 13, 1896. He was originally destined by his father for the profession of an architect; and some houses, he told his students in a festival address, still existed (in 1892) in Darmstadt of which he drew the plans when, a youth, he was attending the gymnasium. The leading events of his life were very tersely told by himself in an address responding to an ovation from the students of the University of Bonn on the twenty-fifth anniversary of his professorship there; a translation of which, from the _Kölnische Zeitung_, was published by Mr. J. E. Martin in Nature, June 30, 1892.

At Giessen, he said, where he went to study architecture, he attended Liebig's lectures, and was thereby attracted to chemistry. But his relatives would not at first hear of his changing his profession, and he was given a half-year's grace to think over it. He spent his time in the Polytechnicum at Darmstadt. His first teacher in chemistry at Darmstadt was Moldenhauer, the inventor of lucifer matches. His leisure time was spent in modeling in plaster and at the lathe. He was then permitted to return to Giessen. "I attended," he said, "the lectures, first of Will and then of Liebig. Liebig was at work on a new edition of his letters on Chemistry, for which many experiments had to be carried out. I had to make estimations of ash, of albumen, to investigate gluten in plants, etc. The names of the young chemists who helped Liebig were mentioned in the book, among them mine. The proposal was then made to me, just at the time Liebig intended to make me his assistant, that I should go for a year abroad, either to Berlin, which was at that time to Giessen a foreign land, or to Paris. 'Go,' said Liebig, 'to Paris; there your views will be widened; you will learn a new language; you will get acquainted with the life of a great city; but you will not learn chemistry there.' In that, however, Liebig was wrong. I attended lectures by Frémy, Wurtz, Pouillet, Regnault; by Marchandis on physiology, and by Payen on technology. One day, as I was sauntering along the streets, my eyes encountered a large poster with the words _Leçons de philosophie chimique par Charles Gerhardt, ex-professeur de Montpellier_. Gerhardt had resigned his professorship at Montpellier, and was teaching philosophy and chemistry as _privat docent_ in Paris. That attracted me, and I entered my name on the list. Some days later I received a card from Gerhardt; he had seen my name in Liebig's Letters on Chemistry. On my calling upon him he received me with great kindness, and made me the offer, which I could not accept, that I should become his assistant. My visit took place at noon, and I did not leave his house till midnight, after a long talk on chemistry. These discussions continued between us at least twice a week for over a year. Then I received the offer of the post of assistant to von Plauter, at the Castle of Reichenau, near Chur, which I accepted, contrary to Liebig's wish, who recommended me as assistant to Fehling, at Stuttgart. So I went to Switzerland, where I had leisure to digest what I had learned in Paris during my intercourse with Gerhardt. Then I received an invitation from Stenhouse, in London, to become his assistant, an invitation I was loath to accept, since I regarded him, if I may be allowed the expression, as a _Schmierchemiker_. By chance, however, Bunsen came to Chur on a visit to his brother-in-law, at whose house I first met him. I consulted Bunsen as to Stenhouse's offer, and he advised me by all means to accept it. I should learn a new language, but I should not learn chemistry. So I came to London, where as Stenhouse's assistant I did not learn much. By means of a friend, however, I became acquainted with Williamson. The latter had just published his ether theory, and was at work on the polybasic acids (in particular on the action of PCl_{5} on H_{2}SO_{4}). Chemistry was at one of its turning points. The theory of polybasic radicals was being evolved. With Williamson was also associated Odling. Williamson insisted on plain, simple formulæ, without commas, without the buckles of Kolbe or the brackets of Gerhardt. It was a capital school to encourage independent thought. The wish was expressed that I should stay in England and become a technologist, but I was too much attached to home. I wished to teach in a German university. But where? In order to get acquainted with the circumstances at several universities, I became a traveling student. In this capacity I came, among other universities, to Bonn. Here there was no chemist of eminence, and hence there were no prospects. Nowhere did there seem so much promise and so great a future as at Heidelberg. I could ask no help of Bunsen. 'I can do nothing for you,' he said, 'at least not openly. I will not stand in your way, but more I can not promise.' I fitted up a small private laboratory in the principal street of Heidelberg at the house of a corn merchant--Gross, by name--a single room with an adjoining kitchen. I took a few pupils, among whom was Baeyer. In our little kitchen I finished my work on fulminate of silver, while Baeyer carried out the researches, which subsequently became famous, on cacodyl. That the walls were coated thick with arsenious acid, and that silver fulminate is explosive, we took no thought about. After two years and a half I received a call to Ghent as ordinary professor. There I stayed nine years, and had to lecture in French. With me to Ghent came Baeyer. Through the kindness of the then Prime Minister of Belgium, Rogier, I obtained the means to establish a small laboratory. I had there with me a number of students, among whom I may name Baeyer, Hübner, Ladenburg, Wichelhaus, Linnemann, Radzizewski. There was not so much a systematic course of instruction as a free and pleasant academic intercourse. After nine years' work I received the call to Bonn." Professor Kekulé concluded his address with some account of his work at Bonn, and of the great attention he had always received from his pupils. For a full account of Kekulé's scientific career and achievements, we are indebted to the memorial address made by President Landelt to the German Chemical Society on the occasion of his death, of which we translate the more important passages from the _Berichte_:

"The works which Kekulé has left behind him belong, as we all know, to the bases of all chemistry. His teachings have so passed into our flesh and blood that it seems almost superfluous to remind a circle of professional chemists of them. I shall be able to present only in the most general outlines this evening the immense influence which the dead master has exercised upon science; a complete view of all his labors is a subject for a biography, which we must wait for.

"Kekulé's scientific work began in 1854, with the discovery of thiacetic acid, by which he at once separated from the old school of chemistry that was still prevailing, and, founding a new one, revealed himself as an adherent of the new doctrine of types. After his habilitation at Heidelberg, which followed in 1856, came the essay on fulminating mercury, in which the view so important for the future was expressed, that to the three typical combinations of chlorhydrogen, water, and ammonia, hitherto recognized, might be added a fourth, marsh gas. In the next essay, on binary combinations and the theory of polyatomic radicals, he put forward the conception of mixed types, and first reached the knowledge of various atomicity or valency of the radicals. These researches were continued, and there appeared shortly afterward, in the spring of 1858, the two great treatises which have since exercised so powerful an influence on chemistry--that on the constitution and metamorphoses of chemical combinations, and that on the chemical nature of carbon. In these theses Kekulé passed from the valency of the radicals to that of the elements themselves, and showed that the composition of all those compounds that contain one atom of carbon lead to the conclusion that that element is quadrivalent; and that, further, the relations of combination of a complex of carbon atoms are explainable if we suppose that the latter are mutually bound by a certain number of their four unities of attraction. This idea was suggested very carefully, and the words which the author added at the end of his essay read very curiously to-day: 'Finally, I think I ought still to insist that I attach only little value to speculations of this sort. Since one delving in chemistry must once in a while, in the lack of exact scientific principles, content himself with probabilities and temporary hypotheses, it seems proper to communicate these conceptions, because, as it appears to me, they furnish a simple and fairly general expression for the newest discoveries, and because, therefore, the use of them may assist in the discovery of new facts.' How diffident the words sound, and how far have the expectations been exceeded! We all know that the theory of valency is to-day the leading guide through all our science; and, although another investigator had a share in its origination, no one disputes that its main foundation and its eminent value in organic chemistry are primarily due to Kekulé's idea of the quadrivalency of carbon.

"After he was called to the University of Ghent, in 1858, Kekulé exhibited an indefatigable activity. He began the great series of investigations of the organic acids which, beginning with succinic acid, malic acid, and tartaric acid, and extending afterward to many others, have given complete conclusions as to the nature of these bodies. Contemporaneously, in 1860, appeared the first number of the _Lehrbuch der organischen Chemie_, which was soon followed by other numbers, so that the whole first volume was completed in 1861. All his fellow-chemists who are acquainted with the events of that period will remember the enthusiasm with which the work was received. For the first time, in place of the former system of organic chemistry based on the old radicals of Berzelius, a system of treatment appeared which in the dress of the theory of types had the doctrine of valency as its foundation, and exposed the construction as well as the isomeric relations of the numerous carbon compounds with wonderful clearness. The work, the first two published volumes of which contained the substances designated by Kekulé as the fatty compounds, is still recognized as the prototype of many text-books that followed it.

"In 1855 Kekulé put forth the second of his great theories. First in the Bulletin of the Chemical Society of Paris, and afterward in fuller form in Liebig's _Annalen_, appeared the essay, Researches among the Aromatic Compounds, in which he showed that the substances so designated all contain six or more atoms of carbon, and that they could be described as derivatives of the simplest of them, benzene. He proposed two hypotheses to explain the constitution of this substance, one of which, the only one afterward pursued, supposed that the six carbon atoms are associated in a ring, and alternately linked by one and two valencies. By replacing the hydrogen atoms corresponding to each carbon atom by other elements or radicals one could arrive at the knowledge of the constitution of a large number of aromatic bodies which now figure as benzol derivatives. These considerations led, however, to another question--namely, whether or not the supplied places of the six hydrogen atoms are chemically equivalent. The question of space relations in chemistry first came up in connection with this investigation, and Kekulé at once endeavored to solve it. All these ideas were, however, expressed at first with reserve, and this essay closes with the words, 'I place no more value on these views than they are worth, and I believe that much labor must still be applied before such speculations can be regarded as anything else than more or less elegant hypotheses; but I believe, too, that at least experimental speculations of this kind must be used in chemistry.'

"In this case, again, Kekulé's modest expectations have been surpassed. The wonderful results that have accrued from the benzol theory are patent to all of us. We know that it was the instigation to the carrying out of an innumerable multitude of researches which are still pursued with undiminished industry. Rarely has a thought exercised so fructifying and forwarding an influence on chemistry, and so redounded to the advantage of both pure science and art. Thankfulness for this gift, as you know, prompted our society to honor the author of the benzol theory and the twenty-fifth year of the announcement of it by a public festival; and the Kekulé celebration, which took place in this house on the 11th of March, 1890, is memorable to all for the brilliant and witty speech with which the master responded to the many addresses made to him. It is preserved in our reports (_Berichte_ 23, 1892), and the repeated reading of it always affords rich enjoyment."

Kekulé assumed his last position, as professor at the University of Bonn, in the fall of 1867. He there devoted his attention for a period to the erection of a new institute building, but it was not long before numerous works began again to appear--some of them by himself alone, like the important investigation of the condensation products of aldehyde; and others in co-operation with his many students. The continuation of his _Lehrbuch_ was taken in hand at the same time. In 1867 he gratified his fellow-chemists by the publication of the first volume of his Chemistry of the Benzol Derivatives. This was followed from 1880 to 1887 by single numbers, prepared with the help of co-workers, of the second and third volumes.

Prof. F. R. Japp, in the Kekulé memorial lecture before the Chemical Society of London, speaking of Kekulé's residence in that city, September, 1897, said that he always acknowledged the influence which Liebig and Odling and Williamson, with whom he became acquainted in London, exercised on the formation of his opinions. Kekulé's theories, Professor Japp said, were based on Gerhardt's type theory; on Williamson's theory of polyvalent radicals, which by their power of linking together other radicals render possible the existence of multiple types; and Odling's theory of mixed types, which was a deduction from Williamson's theory. Less consciously, perhaps, his opinions were influenced by E. Frankland's theory of the valency of elementary atoms, and by Kolbe's speculation on the constitution of organic compounds. Kekulé gathered together the various ideas which he found scattered throughout the writings of his predecessors, added to them, and welded the whole into the consistent system which forms our present theory of chemical structure. In 1857, in the course of a memoir on the constitution of fulminic acid, he gave a tabular arrangement of compounds formulated on the type of marsh gas, this being the earliest statement, though put forward only in an imperfect form, of the tetravalency of carbon. In the same year he published an important theoretical paper On the So-called Conjugated Compounds and the Theory of Polyatomic Radicals, which contains a complete system of multiple types and mixed types. In 1858 the celebrated paper, On the Constitution and Metamorphoses of Chemical Compounds, and on the Chemical Nature of Carbon, appeared. It embodies the fully developed doctrine of the tetravalency of carbon, together with Kekulé's views on the linking of atoms and on the valency of such chains of atoms, the foundation on which our modern system of constitutional chemistry rests. In 1865 Kekulé put forward his well-known benzene theory--pronounced by Professor Japp the crowning achievement, in his hands, of the doctrine of the linking of atoms, and the most brilliant piece of scientific prediction to be found in the whole range of organic chemistry. The conception of closed chains, or cycloids, which he thus introduced, has shown itself to be capable of boundless expansion.

Kekulé's students all speak admiringly of his qualities as a teacher. The memorialist of the German Chemical Society said: "All of us who have attended his lectures or heard him in other places will ever remember what a teacher Kekulé was. With incomparable lucidity and sometimes with the happiest humor, he could go playfully through the theme he was considering, masterfully presenting it in new and often surprising aspects. The charm of his personality affected all who came in contact with him; it was the geniality which shone out of his whole being, and involuntarily commanded admiration. Numerous pupils flocked to him, and many of those who to-day fill chairs of chemistry in Germany and other countries have made his name highly honored."

Professor Thorpe, of London, who spent a little time in Kekulé's laboratory, describes him as having been one of the very best expositors, with the single possible exception of Kirchhoff, to whom it had been his lot to listen. As a laboratory teacher he was excellent. He was a most severe judge of work, striving to exact the same high manipulative finish, the same neatness and order, which he invariably bestowed on everything he did, and he was absolutely intolerant of anything slovenly or "sloppy." "But it was as a lecturer that he was seen at his best. He was singularly luminous as a thinker, a close and accurate reasoner, with a remarkable power of concentrated expression.... His language was apt and well chosen, and his delivery easy and natural"; and his whole address showed that every detail had been carefully considered.

At a distance of thirty years, Professor Dewar said, at the London memorial meeting, that to look back and call to mind the presence and personality of the great chemist as he knew him was indeed a pleasure. He was a man of noble mien, handsome, dignified, and yet of a homely and kindly disposition. He was a severe critic, having a haughty contempt for the accidental and bizarre in scientific work. His originality and suggestiveness seemed endless, so that he had no need to commit trespass or to follow just in the wake of other people's ideas. "Everything that passed through the Kekulé alembic was indeed transmuted into pure gold. His precision of thought and diction rendered his papers profoundly suggestive to other workers."

"The last years of the master's life," his German eulogist says, "were often troubled by illness, but there were not wanting bright days which the love of his students and colleagues prepared for him." Such a one was the celebration of the twenty-fifth anniversary of his professorship at Bonn, June 1, 1892, in which the students and officers participated with cordial unanimity. The ceremony began in the morning with an enthusiastic ovation by the students. The chemical theater was decorated with plants; the benzene hexagon was figured on the blackboard with garlands of flowers, in the midst of which the letters A. K. were wrought in a monogram of roses. Alfred Helle, one of the chemical students, delivered a felicitous address, in which he congratulated his fellow-students on being privileged to sit at the feet of the greatest of living chemists, after which three cheers were given to the professor. Kekulé responded to the offering in an address giving some of the details of his life, from which we have already quoted. Kekulé's personal staff and the officers of the university then presented their congratulations.

In the evening the students honored him with a torchlight procession, it being the third time he had received this, the most conspicuous honor which is bestowed by German students. The first occasion was in 1875, when he declined the professorship at Munich; the second was in 1878, when he was rector of the university, and was given in celebration of the restoration of unity among the students, after a long period of disunion. Among the torchbearers on that occasion was the present Emperor of Germany.

During the later period of his life Kekulé was comparatively sterile. Those who knew him, however, Professor Thorpe says, "would be the first to affirm that this seeming apathy sprang from no natural indifference. There is no doubt that he suffered, even in the early period of middle life, from the intense stress and strain of his mental labors prior to the Ghent period. He too surely exemplified the sad truth of Liebig's saying that he who would become a great chemist must pay for his pre-eminence by the sacrifice of his health. There is reason to know that it was the consciousness of failing power which prevented him from finishing much to which he had put his hand, and that his fastidiousness and his sense of 'finish,' amounting almost to hypercriticism, restrained him from publishing much which he realized fell short of his ideal."

The last time Kekulé's name was brought before the public was on the occasion of the renewal of the ancient title of nobility of his family, as August Kekulé von Stradowitz.

Editor's Table.

_A VOICE FROM THE PULPIT._

We called attention last month to a weak attack on the doctrine of evolution by a certain Mr. A. J. Smith, Superintendent of Public Schools in the city of St. Paul. The only thing which gave any consequence to the deliverance in question was that it was addressed to a large gathering of public-school teachers, who might possibly have been unduly influenced in their appreciation of it by the speaker's official position. We are glad now to learn that, very shortly after the publication of Superintendent Smith's address, an excellent statement of the true relation of the doctrine of evolution to education was made in one of the city pulpits by the Rev. S. G. Smith, who did not boast, as the superintendent had done, of having made an exhaustive study of the subject, but who, nevertheless, showed that he had a grasp of it which the other altogether lacked. The Rev. Mr. Smith's discourse would have merited attention wherever it might have been delivered; but, considered as a pulpit utterance, it seems to us to possess a special and very encouraging significance. We need hardly say that the pulpit has not always been friendly to broad scientific views, but in this case it has spoken with a candor, a breadth, and an intelligence which the lecture platform can not do more than equal, and which it would certainly be too much to look for in all our colleges.

"The law of evolution," said the reverend gentleman, "is as universal in its application as the law of gravitation. It holds that in every realm the simple tends to become complex, and that the complex is more stable than the simple. Motion and matter have a history in which the simple and the indefinite take on variety of organization and definiteness of adaptation." This is a statement in which the author of the Synthetic Philosophy would probably have very little change to suggest. Mr. Smith does not, like so many who discuss the subject in a superficial manner, confound evolution with Darwinism. Darwinism, he recognizes, may, in its particular explanations as to the origin of species and the descent of life, be in error; but evolution is universal in its scope, and can only fail if it can be shown that the fundamental postulates on which it rests, such as the instability of the homogeneous, the continuity of motion, the law of rhythm, etc., are not to be depended on. Must a person have made the circle of the sciences and comprehended all knowledge before he can reasonably profess a belief in evolution? No, says Mr. Smith; when the foundations of a doctrine have been clearly laid, when they have been tested by many different investigators from many different points of view, and when these, almost without exception, affirm that the doctrine is not only in harmony with, but lends a new and deeper significance to, the several orders of fact with which they are individually concerned, any person of ordinary intelligence is justified in considering that doctrine as satisfactorily proved and giving it his personal adhesion.

What chiefly excited the ire of Superintendent A. J. Smith was the contention of evolutionists that the modern child reflects the earlier stages of human development. He asked his audience if they really thought the children of to-day were young savages, and quoted Emerson and Longfellow as authorities on the question. The Rev. S. G. Smith takes up the point and expresses himself as follows: "When it is stated that the child has many points of contact with primitive man, it is not meant that the child is a savage, but that 'in its immaturity' we can learn much respecting it from the study of child races. The child has neither the virtues nor the vices of the savage, but he has many of the mental characteristics. Embryology does not teach that in prenatal life the child passes into the form of every animal in a menagerie, but that its life passes through the stages that mark the great subdivisions of all life. Nor do the comparisons of the child with primitive man imply that he must pass through all the activities of savage races, but that the development of his faculties, the tendencies of his desires, the state of his ignorance, all illustrate the history of the development of the race. Primitive man may be understood by a study of the child, and, conversely, the child may be illustrated by primitive man."