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amount on the south side. A longer time would, therefore, be required to cut an equal width of terrace on that side, hence their lesser width. Such was the case in the development of every one of the terraces; with the possible exception of the highest, which probably began to develop when no high land existed. If each uplift meant the development on the south side of a terrace with an average width of one mile-probably a far too large assumption, as many of them are known to have reached a width of only a fraction of that figure-the time for the development of the twenty-three terraces would have required as a maximum not above 70,000 years. This approaches the estimate of time which has elapsed since the Ice Age.

There is still another line of evidence which has not been mentioned. On the Mingan Islands to the north are many rocks which were called "flower-pot" rocks by Richardson. These are stacks which were developed by the waves, and all of them are at elevations the highest of which probably does not exceed 50 feet. On the top of West Cliff there is also a stack-like structure at a height of a little more than 400 feet above sea-level. Had this structure been there in Glacial time, with its present size, it would most certainly have been shoved away, unless the glaciers did not rise to this height, a possibility which the bowlders lying at elevations almost as high strongly negate.

All lines of evidence hence converge to the conclusion that the terraces were developed in post-Glacial time.

If the terraces are of the age inferred, it follows that there has been a negative movement of the strand-line exceeding 400 feet since the period of glaciation. The existence of the terraces shows that the periods of uplift have been separated by times of relative stability. The hooded cliffs and the "flower-pot" rocks in the Mingan Islands to the north show that the last uplifts have been comparatively recent, otherwise these features would have been obliterated under the strong frost action which prevails on these islands and on Anticosti. Anticosti is

said by the people of the island to be rising at present, as they tell of harbors being no longer accessible to boats which thirty years ago found easy entrance. Mr. Alfred Malouin, who has lived on the island for around forty

James Richardson, Geol. Survey, Canada, Rept. of Progress for the years 1853-1858, p. 242, 1857.

years, states that he is confident that there are parts now above water which were submerged when he first came.

CORRELATION WITH TERRACES ELSEWHERE.

It is extremely difficult to correlate any of the terraces of the island with those of other parts of the St. Lawrence. One may be certain that a terrace of the same time of development is present on both the south and the north sides of the Gulf, but to state the identity in time of development needs far more work than has yet been accomplished. Goldthwait has described a 20-foot terrace and sea-cliff about the lower St. Lawrence, and perhaps the 20-foot terrace of Anticosti is its correlative.

At Ottawa, Johnston has described old shore-lines up to about 690 feet sea-level-more than 200 feet higher than the highest terrace of Anticosti-and has found stratified clays with fossils up to 510 feet. Many beaches are present and some of these must certainly correlate with those of Anticosti, but it is altogether impossible to state which are synchronous.

5

University of Wisconsin, Madison.

J. W. Goldthwait, this Journal (4), 32, 291-317, 1917.

W. A. Johnston, Geol. Survey, Canada, Mus. Bull. No. 24, 6, 1916.

SCIENTIFIC

INTELLIGENCE.

I. CHEMISTRY AND PHYSICS.

1. The Devitrification of Glass-It has been found by ALBERT F. O. GERMANN that the well known peculiar behavior of many samples of old glass upon heating before the flame is a surface phenomenon, and that such glass can be restored to a workable condition by simply washing it with dilute hydrofluoric acid in order to remove a thin film of the surface. This observation is an important one, as it gives a method for utilizing old glass and for repairing old glass apparatus. It is the author's opinion that this surface change is due to the absorption of moisture, but the matter does not appear to be perfectly simple, because it is mentioned that a tube which devitrified badly at first showed no tendency to behave in this way after having been exposed casually to laboratory fumes for more than six months. Perhaps the absorption of carbon dioxide takes part in the devitrification since this might be removed by the action of acid fumes.

H. L. W.

2. A Substitute for Thoulet's Solution.-A. THIEL and L. STOLL mention the employment of heavy solutions for the determination of the density of solids, by floating and sinking, some of which solutions are mixtures of organic liquids and others are aqueous solutions. Among the latter the best known are potassium mercuric iodide (Thoulet) and barium mercuric iodide (Rohrbach). For organic compounds the aqueous solutions are practically the only ones employed, and for most of these solutions of calcium chloride with a specific gravity up to 1.4 answer the purpose, but the authors had occasion to use a heavier aqueous solution and found that lead perchlorate gave solutions up to a density of 2.6. It is more agreeable to use than the mercuric solutions, the solution is mobile and it does not attack the skin to the slightest degree. It can be prepared cheaply by saturating commercial perchloric acid with lead carbonate and evaporating to saturation. This solution is evidently a very satisfactory one for use with many organic compounds, but unfortunately it could be used only with the lighter minerals, since its maximum density is slightly below that of quartz.-Berichte, 53, 2003..

H. L. W.

3. Priestley in America, 1794-1804; by EDGAR F. SMITH. 12mo, pp. 173. Philadelphia, 1920 (P. Blakiston's Son & Co.).— Professor Smith, in writing several recent books, has rendered valuable service to the early history of chemistry in America, and now he has increased this service by presenting the little book under consideration. From contemporary newspapers, documents and books, he has found much interesting information concerning the life and activities during his exile in America of this noted discoverer of oxygen. It appears that Priestley's activiAM. JOUR. SCI.-FIFTH SERIES, VOL. I, No. 3.-MARCH, 1921.

ties in Pennsylvania were largely connected with philosophical and religious work, but nevertheless he did a considerable amount of laboratory work and wrote frequently in favor of the phlogis tic theory, to which, as is well known, he adhered to the end of his life, although his own discovery of oxygen had paved the way long before for the modern views of oxidation. The book presents the subject very well, and is to be recommended to those who are interested in the history of chemistry. It mentions some important incidents, such as the acquaintance of Priestley with George Washington, and an invitation to him by the latter to visit his home at Mount Vernon.

H. L. W.

4. Introduction to General Chemistry; by H. COPAUX. Translated by HENRY LEFFMANN. 12mo, pp. 195. Philadelphia, 1920 (P. Blakiston's Son & Co.).-This is a clear and concise exposition of the principles of modern chemistry as recognized today by the leaders of the science. It should be a valuable guide to those who wish to obtain a clear view of the subject. Besides presenting the older fundamental laws and theories of chemistry. the book discusses the more modern topics, such as radioactivity, the structure of the atom, the phase rule, etc. A short appendix, dealing with hydrogen-ion concentration, has been contributed by the translator.

H. L. W.

5. A Text-Book of Organic Chemistry; by E. DEBARRY BARNETT. 8vo, pp. 380. Philadelphia, 1920 (P. Blakiston's Son and Co.). In this text-book from England the author has described the important classes of compounds both aliphatic and aromatic. He has generalized, however, wherever possible and has thus avoided the introduction of much specific descriptive detail, which is always troublesome to the beginner. General theories have been grouped under one heading in order that they may be more readily referred to when occasion requires. Several pages have been devoted to a description of the original literature and its use. This is indeed worthy of mention since the use of the journals is an essential part of every organic chemist's training and attention should be paid as soon as possible to this phase of the student's work. The book gives a very favorable impression, but unfortunately many errors in typing have escaped the notice of the proof readers.

J. J. DONLEAVY.

6. Comparison between wave lengths of solar and of terrestrial origin. The relativity theory of Einstein offers a prediction that the wave length of light emitted by an element upon the sun should be about two parts in a million longer than that of the same element upon the earth. Such indications of a difference as have hitherto been published have not been accepted as altogether valid. A recent determination by A. PEROT justifies the existence of a real difference. His investigation was made upon the second head of the cyanogen band, 4216, which is particularly favorable for observation on account of its isolation in the solar spectrum. Its wave length was taken as 4197 A, and the measurements made by a spectroscopic interferometer.

As the vapors producing the absorption appear to occur in the more elevated regions of the solar atmosphere they must be regarded as subject to a relatively low pressure. M. PEROT accordingly used as his comparison source a carbon are under a pressure between 22.5 and 30 millimeters of mercury. As the result of his investigation he states that he was able to determine that the difference sought lay between 2.2 and 1.6 parts in a million, an interval which contains the Einstein number.-Bull. Soc. Fr. de Phys., 147, Dec., 1920.

7. The Imaginary in Geometry; by J. L. S. HATTON. Pp. VI, Cambridge, 1920 (Cambridge University Press).-The author's purpose is to develop a generalized conception of geometry and of space in which each of the three coordinates is regarded as a complex quantity of the form xix', y + iy', ziz'. By adding to the axioms of real geometry, but employing its principles and methods, the well known theorems of plane and projective geometry, of trigonometry, and of the conic and conicoid are extended and generalized. It is a book for geometricians only.

F. E. B.

8. The Principles of the Phase Theory; by DOUGLAS A. CLIBBENS. Pp. xx, 382, 198 figures. London, 1920 (Macmillan & Co.). This book on heterogeneous equilibria does not attempt to give a general survey of the whole field. It deals exclusively with systems which contain no vapor phase, the so-called "condensed systems," with the further limitations that only one liquid phase may be present and no solid solutions. Moreover, the practical illustrations considered are all cases of equilibrium between water and salts, though the theoretical principles involved are, of course, applicable to all condensed systems.

Even with these limitations, the field to be covered is a large one, but they make it possible for the author to deal quite briefly with binary systems, and to devote the major part of the book to the more complicated and less familiar systems of three, four and five components. A final chapter deals with graphical methods for determining, from the compositions of the phases present at an invariant point, what reactions may occur there.

The book is good both in plan and execution. There is no conspicuous originality in treatment, but in a field so well developed it could hardly be expected. The author's style is clear, and the systematic and exceptionally thorough way in which the behavior of each different type of system of a given group is discussed before taking up concrete cases, is worthy of special mention. As the treatment is non-mathematical the book should be suitable for the use of readers who are unfamiliar with the subject. R. G. V. N.

9. Lessons in Mechanics; by WILLIAM S. FRANKLIN and BARRY MACNUTT. Pp. XI, 221. Bethlehem, Pa., 1919 (Franklin and Charles).-This and the two companion volumes to be mentioned later have been prepared to meet the needs of the two year schedule in elementary physics which has recently been

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