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Adams, director of the station, on Oneida Lake, and in the Palisades Interstate Park. The surveys, which in the past have been conducted by the department of forest zoology, have been taken over by the Roosevelt Wild Life Station and will be conducted in the main under its auspices.

DR. MABEL L. ROE, who resigned in July as assistant plant pathologist in the Kentucky Agricultural Experiment Station, has recently accepted an appointment as seed analyst in the Dickinson Seed Company, Chicago.

MR. F. W. GLADING, of the Bureau of Standards, has resigned to become industrial engineer for the Baldwin Locomotive Works, at Philadelphia, Pennsylvania.

THE annual dinner of the New York Academy of Sciences and its affiliated societies will be held at seven in the evening, Monday, December 15, 1919, at the Delta Kappa Epsilon Club, 30 West 44th Street. The dinner will be followed by the annual meeting of the academy, to receive reports and elect officers and fellows for 1920. The presidential address will be delivered by Dr. Ernest Ellsworth Smith, on "Applied science and the war." After the president's address there will be given two illustrated talks, as follows: Professor Douglas W. Johnson, on "A geographer at the front and at the Peace Conference," and Professor Henry E. Crampton, on " Tahiti and the South Seas."

AT a meeting held on November 25 in the main auditorium of the New National Museum, Washington, D. C., Professor Irving Fisher, of Yale University, addressed members of the Scientific-Technical Section of the Federal Employees Union and their friends on "The purchasing power of salaries." Professor Fisher elaborated his theory of a stabilized dollar, claiming that an invariable unit of value is of even greater importance than invariable units of other quantities, such as length, weight, etc. The section voted to appoint a committee for a study of the proposal with instructions to report back a resolution granting or withholding endorsement according to the findings of the committee.

Ir is announced that unavoidable circumstances necessitate a change in the meeting place of The Federation of American Societies for Experimental Biology. The meeting will be held at Cincinnati, Ohio, December 29, 30 and 31, instead of at Toronto.

MRS. MARY CLARK THOMPSON has presented to the National Academy of Sciences a fund amounting to $10,000, the income of which is to be applied to a gold medal of appropriate design, to be awarded annually by the academy for the most important services to geology and paleontology. The medal is to be known as the Mary Clark Thompson Gold Medal. Mrs. Thompson previously gave an additional $1,000 for the preliminary expenses of dies.

A UNITED STATES Civil Service examination for superintendent in the Bureau of Fisheries will be held on December 30, 1919. A vacancy at the Key West, Florida, Biological Station of the Bureau of Fisheries, at $1,800 a year and vacancies in positions requiring similar qualifications, will be filled from this examination.

UNIVERSITY AND EDUCATIONAL NEWS

DR. DAVID P. BARROWS, professor of education and later of political science in the University of California, at one time director of education for the Philippine Islands and author of works on the islands, has been elected president of the University of California, to succeed Dr. Benjamin Ide Wheeler. DR. HORACE G. BYERS, formerly of the University of Washington, who was recently appointed chemist in charge of soil investigations in the Bureau of Soils, has accepted the position of head of the department of chemistry at Cooper Union Institute, New York City.

DR. WALTER H. EDDY, who during the war was a major in the Sanitary Corps and served first as assistant director and later as director of the food and nutrition department of the A. E. F., has been appointed a member of the faculty of practical arts of Teachers College, Columbia University, in charge of physiological chemistry.

DR. ERNEST WILLIAM GOODPASTURE has been appointed assistant professor of pathology at the Harvard Medical School.

MR. R. S. TROUP, assistant inspector-general of forests, India, has been elected professor of forestry at Oxford.

Ar the University of Lyons, Dr. Mouriquand has been appointed professor of general pathology and therapeutics in place of Professor Lesieur, deceased, and Dr. Policard has been appointed professor of general anatomy and histology in place of Professor Renaut, who has retired from active service.

DISCUSSION AND CORRESPONDENCE

AN UNUSUAL FORM OF RAINBOW

THE following is an account of a rainbow which, although probably simple enough in theory, was entirely new to the writer and seems to be worthy of record. The refracting spheres were neither falling raindrops nor drops suspended in air. They were drops resting on the surface of a lake but kept from breaking through the lake surface by a surface tension effect. They probably resulted from a fog which had hung over the lake during the night and persisted longer than usual after sunrise. The morning was unusually calm, and no ripples had yet appeared on the lake. The floating drops gave the surface an appearance like that caused by a scum, but close examination showed the individual drops quite distinctly and also showed that the light of the bow undoubtedly came from them, for part of the bow came quite close to the observer.

The bow was seen about nine o'clock according to the daylight-saving bill, or eight by the usual local railroad time. Its appearance was about as shown in the accompanying figure. AB is the western shore-line of the lake, about 200 yards away. The bow was complete except in the following particulars: the part near S was hidden by the shadow of the observer and that of the boat in which he sat; and the part PRQ was inverted, like a reflection of what should have been the crest, the part near R being somewhat less bright than the rest. The ends of this inverted portion seemed to meet

the ends of the larger arc at the shore-line, but there is no reason why such an accidental line should determine the intersection of the two

FIG. 1.

branches. Probably they should meet at the horizon. Owing to the closeness of the observer's eye to the water-level, and the distance of the shore-line, the latter would differ in angular position very slightly from the true horizon. Though the bow was very brilliant, no trace of a second bow was visible.

The obvious explanation of the inverted portion is that it is formed by reflection in the lake surface, either directly before or directly after the light passes through the drop. If the light enters the top of the drop and is afterward reflected from the lake-surface, the reflected ray will clear the drop if the elevation of the sun is greater than 21°.6. If it is first reflected from the lake and then enters the drop at the angle of incidence proper to give rise to minimum deviation, the sun's elevation must be less than 20°.4 in order for the incident ray to clear the drop. These figures are calculated on the assumptions that the drop is spherical, that it rests on the surface, and that the angle of the bow is that given by the elementary rainbow theory.

UNIVERSITY OF MISSOURI

H. M. REESE

A SIMPLE DEVICE FOR ILLUSTRATING OSMOSIS

THE difficulty of preparing a “leak-proof" apparatus to demonstrate osmosis by the use of parchment and thistle tube, led me, last

year, to experiment with other animal membranes. As a result I found that the method outlined below proved uniformly satisfactory.

The skin of a freshly killed or of a preserved frog was cut at the junction of leg and trunk. This cut, entirely encircling the leg, permitted the skin of the leg to be peeled off precisely as a glove is removed from the hand. At the knee joint it was necessary to proceed carefully to avoid tearing the skin. Having pulled the skin off as far as the foot, the bones and sinews were cut. The result was a legshaped sac, open at the top, containing the bones of the foot at its lower end, and entirely free from perforations. The sac was pulled over the end of a glass tube about twelve inches long, and securely fastened by several turns of strong thread. A strong solution of dextrose was poured into the open end of the tube, and the tube shaken until the liquid passed, drop by drop, down into the sac. This process was continued until the liquid stood about an inch high in the tube. The apparatus was supported in such a way that the sac of skin was completely immersed in a tumbler of water. The level of the liquid was recorded by putting a small label on the tube, and the apparatus was ready for demonstration.

The apparatus and procedure described above have the following advantages over any other method that I have seen:

1. Simplicity.-Parts are to be found in any biological laboratory. Entire apparatus can be set up in fifteen minutes.

2. Reliability. It is a very simple matter to secure a water-tight junction of the sac and tube by taking several turns of thread and tying the sac tightly to the tube.

3. Rapidity of Action.-Since there is a large surface exposed to osmotic action, the rise of the liquid in the tube is rapid. It is not uncommon to note a rise of one centi

meter in twenty minutes. This is a valuable point, for it makes possible the recording of data and results in the same laboratory period. A narrow label may be fastened to the tube to mark the level of the liquid at the beginning of the hour. The data are given the

pupil, a sketch of the apparatus is made, and by that time the liquid has risen enough to make possible the recording of the new level and the drawing of conclusions. After the contents of the tumbler have been tested with Fehling's solution, pure water may be substituted, and the experiment repeated.

ELBERT C. COLE HARTFORD PUBLIC HIGH SCHOOL, HARTFORD, CONN.

WHY NOT GOVERNMENT-MAINTAINED

FELLOWSHIPS?

IN recent number of SCIENCE, Mr. E. W. Nelson has called attention to the many opportunities that exist in Washington for research in connection with the various government bureaus. To the end that these opportunities may be more widely appreciated he suggests a closer cooperation between the universities and these bureaus and he suggests that universities might find it possible to maintain fellowships which would permit their holders to work at Washington.

That such opportunities exist is undeniable and there are doubtless a very large number of workers who would be extremely glad to take advantage of them, but that any university will be able to establish even a single fellowship of this type is almost too much to hope for. The number of fellowships of even the ordinary character is still far too few. However, there is another angle from which the matter may be approached.

Why should not the federal government itself maintain a group of such fellowships? The presence in Washington of the Congressional Library, the National Museum and the various government bureaus has at times been used as an argument in favor of the establishment there of a National University. Whether such a university should be established is perhaps debatable and whether if it were established it could effectively utilize these special opportunities is more so. In fact it probably could not. could not. But in the absence of such an institution, or perhaps even in addition to it,

1 Nelson, E. W., "Cooperation between Zoological Laboratories and the Government Bureaus," SCIENCE, XLIX., 409, 1919.

these splendid opportunities might well be made available for the holders of such fellowships as I have suggested.

These fellowships should not be restricted to the purely scientific branches. What better place than Washington for historical research? Where else than in the Department of Labor with such a division as the Children's Bureau could certain social problems be studied to better advantage? Yet it is probable that the majority of such fellowships would be in connection with the scientific activities of the government. For that reason it is from our national scientific societies that the initial impulse for a movement leading to the establishment of such an institution must come.

G. F. FERRIS

SPECIAL ARTICLES

THE TERM "INVERSION"

is

THE diversity among the phenomena which are referred to by the term "inversion so great that at present the word has lost any precise meaning which it may have had in the past. The organic chemist uses it when discussing the behavior of the allotropic forms of a substance and also when alluding to that well-known single-phase phenomenon, the inversion of cane sugar; while the inorganic chemist generously uses it to denote, in addition to the meanings already referred to, such a phenomenon as an incongruent melting.

The writer is not an organic chemist and therefore does not wish to criticize the terminology used by the organic chemists, but feels in duty bound to protest against the present use of the term "inversion" by most inorganic chemists.

When an inorganic chemist hears the term "inversion" used, he invariably associates it with phenomena like the change of rhombic to monoclinic sulfur1 or phenomena like the thermal dehydration of sodium sulfate decahydrate. The first use of the term is, I think, a very satisfactory one, but for the second type of phenomena a different term should be employed, since otherwise there can 1 Findlay, "Phase Rule," page 34 (1908). 2 Ibid., p. 138.

not but result an overlooking of the important temperature interval which characterizes this type of "inversion" in systems of three or more components. The term "transition," now used synonymously with "inversion," could well be confined to phenomena of the second class mentioned above.

The distinctive feature about an inversion such as that of rhombic to monoclinic sulfur is the fact that the inversion temperature is a fixed point at constant pressure regardless of the complexity of the system, provided no solid solutions are formed, whereas in the case of the transition of sodium sulfate decahydrate to the anhydrous salt the transition temperature is dependent, in addition, upon the composition of the whole system. Thus both hydrated and anhydrous salt can coexist in the presence of suitable liquids over a wide range of temperatures. The change of transition temperature by the addition of a third component is not an isolated phenomenon but rather an example of one of the types met with most frequently in phase rule studies of complex systems.

On the theoretical side Bancroft has pointed out as a corollary of the theorem of Van Alkemade that in ternary systems at constant pressure involving no solid solution the temperatures at which two solid phases can coexist in the presence of a suitable liquid will rise as the composition of the liquid approaches the side line, i. e., will be a maximum in the binary system. In other words, in a system such as sodium sulfate: water: sulfuric acid, the temperatures at which the solid phases, sodium sulfate and sodium sulfate decahydrate, can coexist will rise as the liquid becomes less acid and be a maximum when the solution contains no free acid.

With this corollary in mind, the effect

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adding a component to the systems under discussion may be deduced. In the first case suppose we had both rhombic and monoclinic sulfur coexisting, and suppose, keeping the temperature and pressure constant, we added another component. The total quantity of crystalline sulfur would probably be changed but the crystalline sulfur remaining (if any) would consist of crystals of both the rhombic and monoclinic forms. In the second case suppose we had a saturated solution of sodium sulfate and sodium sulfate decahydrate and, again keeping the temperature and pressure fixed, we added a third component. The sodium sulfate decahydrate would promptly disappear and only a saturated solution of the anhydrous salt, together with anhydrous salt, would be left. This will probably appear clearer after a discussion of the diagram given in Fig. 1.

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1

suppose we take a saturated solution of B in contact with crystals of B, with total composition represented by X and with the composition of the solution represented by Y. The isotherms (saturated solutions of A and B) on the concentration diagram are shown by the lines running from Y to Y, to Y2 If now to X we add the third component the total composition will vary along XX. While the total composition varies from X to X, the hydrated salt will persist, and while the total composition varies from X, to X, both salts and the solution Y, will be obtained, but when the composition passes X, only the anhydrous salt and a solution will be obtained.®

2

3

3

2

Enough has been given, I think, to demonstrate the essential differences in the character of the phenomena under discussion and I would suggest that the term inversion be restricted to phenomena like the change of rhombic to monoclinic sulfur, and the term transition to phenomena similar in type to the dehydration of sodium sulfate decahydrate, and that in cases in which the composition of all the phases concerned may be represented by simple chemical formulas, the word dissociation be employed.

In conclusion I should like to draw attention to a distinction made by Findleys between transitions in the solid state and melting point phenomena. He states:

The transition point, however, differs in so far from a point of fusion, that while it is possible to supercool a liquid, no definite case is known where the solid has been heated above the triple point without passing into the liquid state. Transformation, therefore, is suspended only on one side of the melting point. In the case of two solid phases, however, the transition point can be overstepped in both directions, so that each phase can be obtained in the metastable condition.

This has been interpreted by many to mean that a crystalline substance can not exist even 6 See Roozeboom, "Die Heterogenen Gleichgewichte,'' III., part 1, page 190.

7 Writers like Findlay and W. C. McC. Lewis use the words "transition," "inversion," and "transformation" synonymously, while Bancroft in denoting such phenomena uses the word "inversion" almost exclusively.

8"The Phase Rule,'' p. 37.

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