Popular Science Monthly/Volume 1/October 1872/A Glass of Water
By FRIEDRICH MOHR.
IN tracing the history of the civilization and growth of humanity, it becomes noticeable that long periods of time often witness but slow and gradual progress; but that from time to time a few inventions and discoveries of eminent men suddenly kindle a revolution in all the spheres of human affairs. To trace to their source the changes so wrought, presents to the historian and scientist one of the most interesting subjects. In nearly every place, the most ancient of such great events, the invention of language and of written characters, are wrapped in complete darkness. As history can be handed down to posterity by means of language only, it is obvious that ages without language can have no history. It is language which introduces nations into history. As regards written speech the case is somewhat different. The most distinguished people of antiquity, the Greeks, emerged from obscurity into history with a language wonderfully complete, but without written characters. During several centuries the Homeric songs had to wonder from mouth to mouth before they were intrusted to the graphic symbols; from this moment they disappeared from memory. Written language is the downfall of tradition.
The history of the rise of the two great races of antiquity, the Greek and the Roman, is barren of important inventions. Their blue sky made them wellnigh independent of Nature. Amid the cheerful enjoyment of the natural, intellect in Greece flourished as never before or afterward in any clime; the age of Pericles—
"The age of godlike fantasy,
Is vanished, never to return."
The palmy days soon passed away, however; the mountainous land of small extent succumbed first to the Macedonian, then to the Roman victor. The descendants of the conquerors of Asia became private teachers to the Roman grandees.
Rome herself developed into political greatness only. With the exception of her historians, her scientific lustre was merely a faint image of Grecian culture, very much like German literature of the first half of the eighteenth century when compared with the times of Louis XIV. and Queen Anne. No remarkable invention, of lasting benefit to humanity, sprang from the Romans. Even the weapons of war, down to the invention of gunpowder, remained the same as when Glaucus and Diomedes handled them. Shield, spear, and sword, had changed shape and size, but none of their functions.
Not until the invention of gunpowder was the aspect of society essentially changed. A bit of charcoal, a nitre-crystal, and a few grains of sulphur mixed together, made up a powder that rent mountains and crushed walls. At once all the then prevailing systems of attack and defence were overthrown. The nation most advanced in technical matters became the most powerful. With a few thousand blunderbusses, a handful of adventurers conquered a new continent. The history of the invention of gunpowder is as yet a myth. Very likely, an accident was the main cause. Science claims no reward. Then came a series of inventions and discoveries, each of which played an important part in framing society anew. The compass emboldened the mariner to leave the coast for the open sea, and helped to discover a new continent and circumnavigate an old one; the telescope revealed celestial spaces hitherto unknown; the laws of the pendulum, discovered at that epoch, the laws of compressed air, of the circulation of the blood, of the motions of the planets, furnished important building-material with which to rear culture and civilization. The newly-invented art of printing rendered the sources of knowledge accessible to all. Our purpose is not to unfold all this in detail; but it was necessary to show the distances of those stopping-points where history changes horses in order to go forward with renewed vigor. With the invention of printing, history commenced making more rapid strides. A few centuries later, however, events occurred which were originated and put upon the scene by means of the art of printing, and which greatly diminished the blessings of the invention on account of the almost total destruction of national prosperity during the Thirty Years' War. The art itself meanwhile had not improved. The prints of those times are poor and wretched compared with the excellent works of Gutenberg. The importance of the art by far exceeds its intellectual merit. Many inventions have since been made, which involve far higher intellectual endowments than the invention of printing. The Jacquard loom, the stocking-frame, the carding-machine, the watch, the chronometer, and other inventions, unquestionably involve rarer gifts of combination and executive force; yet, as regards influence, none of them can even remotely be compared with the printing-press; none would at that time have come to light without the press.
This vast capital handed down to us by former generations, modern humanity has immeasurably increased, even doubled and trebled. The inventions and discoveries mentioned thus far are fully known, as to their immense bearing upon the direction of human life.
In addition to these, let us record two events of the second half of the last century, which, more promptly and thoroughly than even any of the preceding, changed the entire social conditions of humanity: one an invention, that of the steam-engine; the other a discovery, that of oxygen.
The importance of the steam-engine requires no comment. Man derives power from the rays of the sun which were stored up as carbon in the vegetable kingdom from time immemorial. The steam which today gushes from the locomotive is an equivalent of the rays that decomposed the carbonic acid of the huge marine plants of those early periods, and accumulated the carbon as a source of power—a sleeping affinity, a lifted weight. In combining this carbon again with oxygen, we produce precisely as much heat as disappeared during the growth of those plants. The steam generated by this heat we allow to push against a movable obstacle, and to this obstacle we attach the resistances to be overcome—a train of cars, a number of looms or hammers, grindstones or rolls. The power is neither given us nor is it generated. It disappears with the wood or the coal.
The discovery of oxygen has an altogether different importance. We are confronted by an apparently insignificant fact which Destiny seemed for a time to have permanently assigned to the chemist's laboratory. It was on the 1st of August, in 1774, that Priestley, an English clergyman and a naturalist, for the first time performed the celebrated experiment which up to the present day is repeated in nearly every course of lectures on experimental chemistry. He heated red oxide of mercury in a small glass retort, and obtained an invisible, colorless gas together with drops of liquid mercury. To collect the gas he employed the same means which we still use to-day. He took a glass, filled and inverted it under water, and lifted it inverted so that it remained full on the surface of the water. Then he made the new gas pass through a tube and rise under the glass; the ascending bubbles soon filled the vessel with the pure gas. Thus he had oxygen collected in a glass of water; he held the microcosm in his grasp, and could investigate its properties. Almost at the same time the gas was discovered by the Swede Scheele, who prepared it by heating oxide of manganese. This was but one step, however; the substance that was to initiate a new era in the world was discovered but not yet recognized. As yet an error swayed the mind of man.
The phenomenon of combustion which, at the present time, is ascribed to the chemical union of oxygen with combustible bodies, was at that time explained as due to the escape of an unknown fire-substance called phlogiston. The products of combustion were said to be dephlogisticated. That substance was thought to escape from the burning body during the act of combustion; and yet experience demonstrated that the result of the combustion, such as, for example, the rusts of lead, zinc, and copper, had more weight than the original metals. In reply to this, it was maintained that the phlogiston possessed negative weight (that it buoyed up the substances on account of its levity). Thus error begat error. At length the mystery was solved by Lavoisier. He distinctly recognized the nature of oxygen as that of a simple body, and asserted that combustion was the combination of a substance with oxygen. This introduced the element into chemistry, a conception which formed at once the basis of an exact science. Priestley was the Copernicus of Chemistry, Lavoisier became its Kepler.
An immense number of familiar facts now easily clustered around this fundamental conception; and the so-called antiphlogistic system sprang into life, a system which has prevailed up to this day, although its name is no longer in use, there being no purpose in maintaining a term that would perpetuate the memory of an error.
The system met with the fate of that of Copernicus; after a protracted struggle it came out victorious, the tenet of every naturalist now living. Oxygen being the most frequently-occurring substance, entering into combinations with all bodies, forming eight-ninths of the weight of water, and over one-half the mass of our globe, and being the conspicuous element ever present in the phenomena of combustion and respiration—it was eminently the substance to establish the new system everywhere. More than half the science of chemistry is taken up by oxygen and its compounds. Priestley and Scheele, its discoverers, remained to the ends of their lives enemies to the new theory. On the 16th of Floreal, in the year II. of the French Republic, Lavoisier was compelled to lay his head under the guillotine.
The composition of water was discovered by Cavendish. This completed the antiphlogistic system. Water consists of two gases, oxygen and hydrogen, which, with the characteristics of combustion, combine to form the well-known liquid. This fact was of such paramount importance, that at great expense a whole glass of water was produced by combustion, and the water was shown to possess the identical properties of pure rain-water.
In the beginning, chemistry, being still a young science, had to attend to domestic arrangements. It must first obtain the substances and contrive the apparatus wherewith to explore the natures of the various bodies composing our globe. A celebrated period soon followed, during which every number of a scientific journal would be filled with important and most momentous discoveries. So glorious an epoch as this probably never before occurred in the history of mankind. New elements, new compounds, were discovered—unknown compounds separated into their component elements. The discovery of the alkaline metals and earths was an event which astonished the world. The natures of such bodies as would not yield to analysis were divined, and subsequent experimentation has verified the speculations. Thus the presence of a metal in clay, lime, and quartz, was distinctly foretold; fifty years later it was actually produced.
The consequences of any discovery are incalculable. Davy investigated the nature of the flame, and communicated his discoveries in a lecture before a large audience. He demonstrated that it was within our power to produce a flame which, at a state of extreme heat, contained either free oxygen or unburnt carbon; that a large grate with a limited supply of coal would generate the former, the oxidizing flame, while a small grate with a larger amount of coal would yield the other, the flame devoid of oxygen, but in which combustible substances might be melted without the danger of combustion. Among the hearers sat a young man by the name of Cort, who directed his mind to these remarks. Up to that time cast-iron was converted into wrought-iron by heating it with charcoal and exposing the melted metal to a blast of air. By this process only small quantities of wrought-iron were obtained at a time, through the necessity of producing but one bloom in a heat, which might easily be hammered out; and also on account of the cost of charcoal. In this process mineral coal could not be placed in contact with the iron, because the never-failing presence of sulphur in that kind of coal would render the iron unfit for use. From Davy's lecture on the flame, Cort struck upon the idea of decarbonizing cast-iron without exposing it to the danger of the contact with coal, by allowing the flames only of the coal to play upon the cast-iron. Thus originated that wonderful operation called the puddling process. Large quantities of cast-iron are melted on the floor of a reverberatory furnace (so named from having an arch which throws the flame back on the iron), and a portion of the carbon in the iron is burnt up by the oxidizing flame; as soon as the iron passes from the liquid state to a pasty condition, the puddler rakes it by means of a long iron bar called a paddle, and finally separates the whole mass of iron into large lumps, each weighing from 60 pounds upward. After this, the opening in the door of the furnace is closed, and the hot oxidizing flame allowed to impinge upon the halls until they are completely converted into bar-iron. The balls are then placed under a hammer; and, the melted slag being forced out, they are rolled into bars between the puddling-rolls.
The ancient mode of refining iron needed no rolls, a hammer was sufficient; nowadays, the huge quantities of refined iron turned out by the puddling-furnace require more than a hammer. The invention of the puddling-rolls was the natural sequence of the puddling-furnace. This furnace yields more than a hundred times the quantity of bar-iron produced by the bloomery of former times; and the blooms—or balls—can be made of a size sufficient to be turned into iron rails of from 16 to 24 feet in length.
At this point let us cast a glance upon the past. We are contemporaries of the great discovery which shortens the distances upon the globe. About forty years have passed since the first locomotive dashed over the track, and already our social and political conditions are mainly dependent on this invention. Not many years ago, a whole army was conveyed from the southern part of Germany to the north within a few days, and this without a straggler—an operation formerly requiring months. In 1866 we saw how an army, equal in size to the one that perished in Russia in 1812, started from the farthermost limits of Germany, was moved in a very short period to another field, and arrived there at the appointed time. Within a day or so, Germany or France can be passed over in its longest extent. The rapid supply of local wants by the importation of grain and cattle acts most powerfully upon the stability of prices. A famine, in the proper sense of the word, can scarcely be thought of at the present time, unless it be a universal famine. Fresh sea-produce, which formerly gladdened only the coast-land, penetrates now into the interior. Districts far remote from the commerce of the earth, but crossed by the iron track, can now take their produce to the great markets of the world. Hence it cannot be denied that the form of modern society depends upon the railroads. But where would our railroads be if we could not roll rails? Where the rails, if we had no puddling-furnace? Where the puddling-furnace, without a knowledge of the flame? And this knowledge is simply the result of the study of chemical science, which, in turn, may be traced back to the discovery of oxygen. This whole series of wonderful effects and causes dates from that glass of water in which Priestley first collected oxygen. Not a member of that series could have been passed by, not a link of that chain been wanting, without rendering impossible the remaining links. It can be asserted fearlessly, that the favorable condition of modern society has its rise in the discovery of oxygen.
Let me here allude to those stupendous processes, the manufactures of sulphuric acid and of soda. To sketch the influence of chemistry upon life would carry us too far. Glass and soap are better to-day, and, despite their hundred-fold increased consumption, no dearer than in former times. Chlorine, as a bleaching agent, in place of the sun, has restored to agriculture thousands of acres of meadow-land.
But the powerful impulse carried also the kindred sciences. The Italian physician Galvani accidentally noticed the convulsions of a frog recently killed, whenever he touched him with two metals in contact with each other. This observation became the starting-point of the electric telegraph. The experiments of Volta resulted in the pile named after him. Two heterogeneous metals, such as zinc and copper, are immersed in a glass of water, to which a few drops of sulphuric acid have been added; both metals we connect by means of a long wire, and then we find the wire possessed of a new force which can transmit a motion through the distance of a hundred miles and over. For a long time the voltaic pile had been the subject of unsuccessful experiments for the purpose of finding its relation to the magnet, to which, on account of its poles, it bears a certain resemblance. One day, Oersted, at a lecture in Copenhagen in 1819, noticed that a magnetic needle on his table was disturbed by a communicating wire that happened to pass over it. He removed the wire, and the needle resumed its polar direction; he then replaced the wire, and the needle again turned aside. Electro-magnetism was discovered. At once he recognized the immense bearing of the phenomenon, repeated the experiment in presence of the magistrate, a notary public, and other witnesses, and made a Latin affidavit; this places his name, for all time to come, among the benefactors of the human race. The advantage of his invention is enjoyed by all of us who daily read telegrams from distant parts of the world as if this rapid transmission of news were a matter of course. The wonder has become a fact of daily occurrence; it rises with us and accompanies us through the day. Do you ever consider that, without this discovery of Oersted, the telegraph would not exist?
We place thirty or forty glasses of water in adjacency, each containing a plate of zinc and one of copper, together with a small quantity of sulphuric acid; we join the vessels by means of metallic wires soldered to the opposite plates, and connect the two extreme plates of the series with the ground, the extreme zinc plate by a short wire, the last copper by, say, a hundred-mile wire. A slight pressure of the finger upon a knob supported by a spring, and a dash or dot is produced a hundred miles away; thought is transmitted to that distance by the electric current; it makes its own record, the recipient needs simply to read off the marks. And through still greater distances it may be flashed by what is termed a relay, so that there is no greater difficulty in forwarding a dispatch from New York to San Francisco than from New York to Boston.
The more securely chemistry had established its household, the more willingly were its services offered to its neighbors. In investigating the composition of minerals, an exact science was created out of our collections of specimens. What meaning had a mineral whose constituents were unknown, in which nothing was observable but what every layman could perceive, viz., color, hardness, and form? Owing to chemistry, mere knowledge about minerals ripened into the science of mineralogy; she induced basalt and granite to yield a glass of water, and taught the process of their formation.
Casual observations had shown that certain substances changed their color on exposure to light. This was especially the case with several silver compounds. The attempt to utilize this property resulted in the invention of photography. A film of albumen or collodion on a glass plate contains a material which, together with silver, makes up a substance sensitive to the action of light. Thus prepared, the glass plate is immersed in a glass of water containing an argentic solution. When the plate is exposed in an optical apparatus to the action of the luminous rays of an object, the result of this action is an image produced on the plate, though invisible to the eye. In the places acted upon by the light-rays, the connection between the constituents of the sensitive argentic substance is not dissolved entirely, but rendered very unstable. The additional action of an oxidizing agent, such as a ferrous salt or pyro-gallic acid, causes opaque metallic silver to be formed on the lighted parts of the image, and a reversed picture, the so-called negative, is produced. The plate is now dipped again into a glass of water, containing a substance which removes the last traces of the sensitive coating, leaving the darkened picture behind. In this way the negative is protected from any further influence of light. Of course, the picture is not recognizable, for the lights and shadows are reversed, but by the same process they can be reversed a second time. A sheet of paper is covered with albumen and thereby sensitized, then laid under the negative and exposed to the action of the sun. The parts of the paper under the darkened portions of the negative remain unchanged; those under the lighted portions are changed by the sunlight. On their withdrawing, by means of hyposulphite of soda, the sensitive substance remaining on the paper, a real picture of the object, the so-called positive, is obtained. This wonderful process of sun-drawing was also involved in the discovery of oxygen, albeit that accident and planless searching had much to do with it. Accident, however, was unthinkable, had not chemistry first defined the substances and their properties. In photography great use is made of iodine, an element existing in the ocean. An eminent chemist, Gay-Lussac, investigated and described this body, without which no photograph can be made. Who would have thought at that time that the violet vapors of iodine contained both an invaluable medicine and photography?
The most difficult task for chemistry was the investigation of the laws of life. All that was known in regard to this was, that the living organisms of the animal and vegetable kingdoms consisted of a few elements, say three or four, which were the same in both. The difference, then, in the manifold organisms of the kingdoms must needs be quantitative; and here the first want was an accurate method of analysis. This presented a difficult problem. The first successful experiments date back as far as 1809, but the method of determining weight was as yet so complicated and wasteful of time, and required so much skill and practice, that only a few substances could be analyzed. To investigate the two organic kingdoms with greater hope of success, an easier method of analysis must be found, and here we meet the name of a man whom Germany proudly calls her own.
To Justus Liebig belongs the merit of having discovered a method by which, without loss of accuracy, the whole process was greatly simplified, and of which he himself made extensive use. As his great teacher, Gay-Lussac, had done before him, he burned the organic substance to be analyzed, in a dry glass tube with oxide of copper, condensed the resultant water in an apparatus containing a water-absorbing salt, calcium chloride, and the resultant carbonic acid was absorbed in a glass of water. This last was a glass of a peculiar shape, with a clear liquid consisting of an aqueous solution of pure caustic potash. This glass of water, which has rendered such great services to humanity, bears the name of "Liebig's potash apparatus," and appears on his pictures as interwoven with the clouds of the higher regions, thus enabling the chemist to recognize the portrait even without the signature.
By that simplified method and by the aid of the labors of his many talented students, who now adorn most of the chairs of chemistry in Europe, as well as through the geniality of the master, the immense material from which he reared the structure of organic chemistry could be collected and properly used. Agricultural chemistry may be considered a part of organic chemistry; its province is to determine the laws of the growth of plants. The year 1840 is of the same importance in the history of the world as the years 1436, 1492, and 1774, which mark the invention of printing, the discovery of America, and that of oxygen.
A report upon the application of chemistry to agriculture, which Liebig had agreed to prepare for the British Association for the Advancement of Science, convinced him of the fact that the then existing views regarding this subject consisted mainly of errors. Instead, therefore, of reporting upon agricultural chemistry, he must first create the science. He demonstrated this in the ever-memorable report which may be said to contain nearly three-fourths of the agricultural chemistry of the present day. The immense materials collected by him and his assistants were of excellent service in this work, for they had closely investigated almost all the familiar ingredients of animals and vegetables, and, after comparing them, induced the great laws of nutrition and the mutual dependency of the two orders. He found that plants derived their nutriment solely from inorganic substances, taking their carbon from carbonic acid, their nitrogen from ammonia, their hydrogen from water; that animals drew their sustenance from organic substances only; that vegetable albumen had the same composition as the albumen in the egg and the blood, and that its admission was the result of its being dissolved by digestion. He then first announced the theory that the inorganic constituents, the so-called ashes, played an important part in the growth of vegetables, and that without their presence no vegetable structure could subsist. Thousands of facts and results of experiments had previously existed, but no one had found the law. After Liebig's announcement and demonstration, it became the starting-point of a new science.
He has not been spared the struggles which Copernicus and Lavoisier had to encounter; yet it may now be said that the warfare has terminated in his favor. The ships searching for guano-islands on the coast of Peru and in the Pacific Ocean do so upon the advice of Liebig; the agricultural colleges and similar institutions which sprang from his breath, may now be counted by the dozen. He was the first to assert that the most important changes and revolutions in the history of the world arose from the destruction of the wealth of the soil; and that the conquerors of the savage hordes of Central Asia were forced to march on by the violation of a law of Nature. Now, since the change of habitations is an unavoidable, ever-occurring element in the world's history, he who must be considered the greater conqueror is the man who teaches humanity what to do in order not to fall again a prey to Nature's law. Attila and Alaric were driven onward unconsciously, because forced by a natural law; far superior, far more powerful, is the natural philosopher who unfolds the law and teaches how to obey it. More enduring than the supremacy of the Roman Empire is the influence of that knowledge which teaches man how he may live on a soil for an unlimited period of time and with ever-constant result.
All this the illustrious inquirer obtained from the accurate investigations of animal and vegetable bodies; but the results would not have been possible without the improved method of analysis contained in that glass of water.
The causes of great inventions and discoveries have always been small, the results always incalculable—as incalculable as those of the glass of water spilled at Queen Anne's court. The investigator of Nature, therefore, must value every observation, every new fact, for they may result in a glass of water.