Popular Science Monthly/Volume 5/September 1874/Editor's Table

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THE comet has come and gone, and again, raised the perplexing question as to what such bodies are made of, and what are the most subtile forms of matter diffused through the celestial spaces. Of the great moving masses which compose our own system, from the sun—1,000,000 times larger than the earth—to the little asteroids—250 miles in diameter—and from these down to the meteorites of a few pounds in weight, which strike the earth, we have become quite familiar, while spectrum analysis has carried us a long way toward the conclusion that there is a unity in the material composition of the universe. But, as every thing is in motion, and all the celestial masses are revolving and whirling at great rates of speed, and, as there is much evidence of fractures, collisions, and transformations, it seems impossible that there should not have been going on constant abrasions and comminutions, with the production of all grades of dust down to the most impalpable, as a consequence of the general wear and tear. Such a notion would, of course, have been inadmissible in old times, when people reasoned about the universe from their a priori notions of what it ought to be; and, holding that the heavens are the type of all perfection, they would have been shocked at the notion that the gearing of the spheres could not work without the production of dirt and dust. But we have survived those prejudices, and now search for the celestial débris and waste with just as much interest as we do for more imposing and dignified objects.

It is but a few years since the world was surprised and delighted by that brilliant series of researches made by Prof. Tyndall, on the formation of artificial clouds and artificial sky by the electric light, in his vacuum-tubes. Spaces, washed clean, and apparently pure, were found to be filthy with dust, and, beginning with the thinnest transparent vapors, he was able to develop a succession of the most exquisite cloud-forms definitely related to the colors of the spectrum as the molecules grew in complexity under the chemical transformation. The firmamental blue he found to be caused by impurities in the air, so attenuated as to react only with the finest waves of the ethereal medium. How far down in the scale of minuteness beyond all previous conception the particles are, which reflect the azure light of the sky, may be gathered from the following memorable passage, taken from Dr. Tyndall's "Fragments of Science" (page 148):

"From their perviousness to stellar light and other considerations, Sir John Herschel drew some startling conclusions regarding the density and weight of comets. You know that these extraordinary and mysterious bodies sometimes throw out tails 100,000,000 of miles in length, and 50,000 miles in diameter. The diameter of our earth is 8,000 miles. Both it and the sky, and a good portion of space beyond the sky, would certainly be included in a sphere 10,000 miles across. Let us fill a hollow sphere of this diameter with cometary matter, and make it our unit of measure. To produce a comet's tail of the size just mentioned, about three hundred thousand such measures would have to be emptied into space. Now, suppose the whole of this stuff to be swept together and suitably compressed, what do you suppose its volume would be? Sir John Herschel would probably tell you that the whole mass might be carted away at a single effort by one of your dray-horses. In fact, I do not know that he would require more than a small fraction of a horse-power to remove the cometary dust. After this you will hardly regard as monstrous a notion I have sometimes entertained concerning the quantity of matter in our sky. Suppose a shell to surround the earth at a height above the surface which would place it beyond the grosser matter that hangs in the lower regions of the air—say at the height of the Matterhorn or Mont Blanc. Outside this shell we have the deep-blue firmament. Let the atmospheric space beyond the shell be swept clean, and let the sky-matter be properly gathered up. What is its probable amount? I have sometimes thought that a lady's portmanteau would contain it all. I have thought that even a gentleman's portmanteau—possibly his snuffbox—might take it in. And, whether the actual sky be capable of this amount of condensation or not, I entertain no doubt that a sky quite as vast as ours, and as good in appearance, could be formed from a quantity of matter which might be held in the hollow of the hand."

Whatever may be the validity of these quantitative speculations, all the lines of investigation seem to converge to the conclusion that there is such a thing as a cosmical dust, and that this form of matter, subtile as it may be, is by no means without effect in the operations of the universal scheme. The inconceivably rapid growth of the tails of comets directed away from the sun, and the mighty sweep of their movements, seem inconsistent with the direct flight or passage of cometary particles, and the effect is now rather explained on the hypothesis that matter already existing, diffused through space, may become in some way electrically polarized and rendered luminous through the mutual action of the sun and the comet. A recent writer suggests that "these polarized particles, or molecules of vapor, require time to become depolarized and to lose their luminosity, which fact may at least in part account for the breadth of the illuminated space or the apparent spread of the tail." The earth is believed to have passed through a portion of the tail of the comet of 1861. On the 30th of June its distance from the earth was rather less than 13,000,000 miles, and its train was computed to be 20,000,000 miles in length. The positions were such that it is quite possible that, on the evening of June 30th, the earth might have been involved in the tail, while certain unusual phenomena of an electrical nature were actually observed at that time. The writer on "Comets," in Brande's "Cyclopedia," says:

"It is a remarkable and significant fact that, not only in various parts of England and Ireland, but also in Spain, Italy, Switzerland, and other Continental countries, a very peculiar phosphorescence, or illumination of the sky, was perceptible during the early hours of the night in question, which many persons supposed to be caused by the aurora borealis, unusual as the phenomenon is In the summer months, especially in the south of Europe; at the same time it was remarked that the luminosity of the sky did not resemble the usual effect of the aurora, but was something quite exceptional. We incline to attribute the phenomenon to the presence of cometic matter (if matter it can be termed) in our atmosphere."

A new set of researches has recently been made known in Poggendorf's Annalen for March, of the present year, which seem to have a further bearing upon the problem of a universal dust. Prof. A. C. Nordenskiöld, of Stockholm, has instituted a series of investigations into the nature of the fine matter entangled and brought to the earth in great snowstorms. After one of these great storms, which occurred on December 1, 1871, he melted a quantity of the newly-fallen snow to ascertain whether it contained any solid particles. A cubic metre was thus tested, and found to contain minute traces of metallic iron and of carbon. He made a second experiment in Finland, in the midst of a large forest, and again particles of carbon and metallic iron were found. Desirous of extending his observations to widely-separated tracts, in 1872 he several times collected snow at localities north of the island of Spitzbergen with the same result—analysis showing the presence of iron, nickel, and cobalt. This dust from the snow greatly resembled a powder previously discovered by him on some islands thirty miles distant from the coast of Greenland, and was probably identical with it. The latter he has called Krykonit, and he was able to collect large quantities of it, and to prove that it contains organic matter, in addition to its other ingredients. It seems highly probable, if not indeed quite certain, that this dust, collected in the snow, is of cosmical origin, and is to be ranked with meteoric matter.



This event went off with great success and satisfaction, according to arrangement, July 31st and August 1st, at Northumberland, Pa., where the great discoverer spent his last days. There was an excellent representation of American chemists from all parts of the country, the exercises were spirited and appropriate, and the entire proceedings vindicated the excellent judgment of the committee who had made the arrangements.

The sessions were held in the new high-school building, and its large hall was crowded with strangers and citizens. Prof. Croft read a brief address on the character of Priestley, which was marked by a broad appreciation of his strong and many-sided traits. The subject, however, was much too large for the time given to it, and the sketch had the effect of awakening more interest than it gratified. The speaker apologized for his performance on account of the short time that had been allowed him to prepare it, and it is to be hoped that he will be enabled to give it greater fullness before publication in the volume which will embody the proceedings.

Prof. Horsford read several manuscript letters of Dr. Priestley belonging to the Massachusetts Historical Society, and not hitherto published. They were written in this country, to a friend, and are valuable as disclosing his opinions concerning questions of American politics, in which he took no public part. They were written with terseness, point, and vigor, and displayed an independence of spirit and an acuteness of observation and reflection that elicited the cordial applause of the audience who listened to them. Prof. Croft had alluded to a rumor, on the authority of the French chemist, Dumas, that Priestley died of poison; but he had been unable to find any verification or explanation of it. One of the letters read by Prof. Horsford threw light upon the matter, as Dr. Priestley wrote to his friend that the ingredient found in the flour used by the family turned out to be, not arsenic, but tartar-emetic.

Prof. Sterry Hunt gave an interesting address on the progress of theoretical chemistry since the time of Priestley, in which, after an acute and instructive analysis of the influence of Lavoisier in giving effect to Priestley's discovery and laying the foundation of modern chemical philosophy, he went on to trace the successive modifications of theory, the growth of the unitary system, and the fundamental ideas of the chemical science now generally received. Prof. Hunt's statement was deficient, in that it did not recognize the share that the speaker had himself taken in promoting the new views, but, aside from this, it was a remarkably clear and instructive presentation, in a narrow compass, of a subject not easy of popular exposition.

Dr. J. Lawrence Smith read a valuable essay on the general progress of chemistry as applied to the arts during the last hundred years, which was full of interesting information, and was listened to with close attention by a large audience. The relation of the industries of the world to the work of the laboratory was skillfully treated and vividly delineated.

In the cemetery of Northumberland, situated upon an eminence back of the town, and commanding a most beautiful view of the river and mountain scenery, rest the remains of Priestley, marked only by a simple tombstone. The strangers present in town, accompanied by many of the citizens, visited the grave at the close of the first day's proceedings, and there listened to an eloquent and appreciative eulogy of the illustrious man by President Coppee, of Lehigh University.

The public exercises were fitly concluded, on August 1st, by a most interesting address from Prof. Silliman, on the progress of chemistry in this country since the time of Priestley. The son of one of the eminent pioneers of the science on this side of the Atlantic, Prof. Silliman has been a student of the subject from his boyhood, there being, perhaps, no American more familiar with its history, or better qualified to present it. He labored under the difficulty of all the speakers, that his subject was too extensive to be treated in the time at command, and we hope that this difficulty will be amply repaired when his essay is printed, for a good history of the growth of American chemistry is much needed. The effect of the centennial contributions to the historic literature of the subject cannot fail to be favorable to the increasing cultivation of the science, both in its theoretical and practical aspects.

A feature of the occasion of peculiar interest was the collection of various memorials of Dr. Priestley, conveniently arranged in a large room for general inspection. There were many vestiges of the apparatus he used in his chemical investigations, and of his microscopical and electrical instruments. There were also copies of his numerous works in various languages, and several portraits and engravings, illustrative of the events and circumstances of his life. These relics were of great interest, and were examined with much curiosity by those who had made the pilgrimage to the scene of his closing labors.

The house which Dr. Priestley built, and in which he died, was also visited, and found to be in a good state of preservation. It is an ample wooden structure, plain, but thoroughly finished. Attached to it on one side was his laboratory—a large apartment, with a chimney in one corner for the escape of chemical exhalations. The situation of the dwelling was once fine, the spacious grounds sloping down to the Susquehanna, and being covered with trees. But there is now a canal in front, and a railroad at the back-door, which render it ineligible for a residence; and the pilgrims were informed, by a conspicuous sign, that it was "for sale." It seems there has been a rumor that the house was haunted, but this was strenuously denied on the part of those who were interested in disposing of it.

The descendants of Dr. Priestley, to the sixth generation, are to be found in Northumberland, and, as we might naturally expect, the family has been prominent in the history of the town. Dr. Joseph Priestley, a leading physician of the place, and his brother, Marks B. Priestley, great-grandsons of the old doctor, are prominent citizens, and their doors were thrown open with a cordial hospitality to the strangers who had come together to honor their illustrious ancestor. Other citizens, moreover, gave a kindly and generous welcome to the visitors, and did all in their power to make the occasion as pleasant as it must ever be memorable to all who participated in it.



It cannot be otherwise than gratifying to all the friends of improvement in the higher culture of the country to have noted the recent indications of a rapidly deepening popular interest in the subject. That an intelligent public such as ours should entertain a profound concern for its common schools, and strive incessantly for their amendment, is nothing more than might be expected; but, that vast multitudes of people should be stirred with intense solicitude about the result of the latest reform in collegiate education is no less remarkable than encouraging. It has been reproachfully said that people brought up under a popular form of government, with equal rights, claims, and privileges, will become so steeped in democratic sentiment as to have little care for that high and thorough training which but a small and select portion of the community can attain, and for which it is the main office of universities to provide. But we have now before us indubitable proof that crowds of people of all sorts and grades may be agitated to the utmost depths and carried away in enthusiasm over the workings of our collegiate system. At the late competitive examination, held at Saratoga, to decide upon the relative attainment in a new branch of scholarship, nine of the leading colleges of the country entered the lists, and the concourse of people that gathered to witness the exercises and note the result was something altogether unprecedented among educational exhibitions on this side of the Atlantic. It can no longer be said that learning and its devotees are unappreciated by our people. They came from all parts of the country through the sweltering heat, were thickly stowed away in suffocating bedrooms, relished the stale mutton and wilted cucumbers furnished by the landlords, and trailed day after day through miles of grime and smudge to reach the place of intercollegiate trial, and went wild with tumultuous excitement when one group of students exhibited greater proficiency than the rest. It was a great event for the higher education of this land, and will no doubt result in many new accessions to the college classes, and in raising still higher the standard of attainment in the new direction of study.