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nection with the heat of dilution for the same concentration we can determine the constants of the formula. With these we can then calculate the osmotic pressure at 100° C. and compare it with the value found for this quantity from observations of the elevation of the boiling point. I was able to do this with the observations of Kahlenberg on the freezing and boiling points of sodium chloride solutions combined with those of Thomsen on the heat capacities and of myself on the heats of dilution. The agreement of the observed boiling points with those predicted from the formula was excellent. Incidentally this agreement confirms the validity of the assumption from which the formula was derived, that a is independent of the temperature.

Another test of a less searching character can be made by using the osmotic pressures given by the formula at different temperatures to calculate the ratio of the vapor pressure of the solution to that of the pure solvent. According to von Babo's law this ratio should be independent of the temperature. Calculations for sodium chloride solutions show that while it is not strictly the same at all temperatures between oo and 100° C. yet the differences between ratios at different temperatures are excessively small, and lie within the errors of the observations by which von Babo's law has been tested.

The terms a and e of the formula for the heat of dilution are manifestly not quantities which are fundamentally kinetic in their nature. They express rates of change of energy with change of volume. Their appearance in the formula for the osmotic pressure indicates that the osmotic pressure is not to be explained as a kinetic phenomenon, as the pressure of a gas is, but as the result of forces acting between the solute—its molecules and ions—and the solvent. These thermal relations, therefore, afford strong evidence, and evidence with as little admixture of hypothesis as is possible in the nature of the case, first of the validity of the dissociation hypothesis by which the laws of electrolytic conduction are explained, and secondly, of the dependence of the osmotic pressure on the forces which are exerted between the parts of the solution and the pure solvent.





(Read April 20, 1912.)

The charts exhibited embody the results of magnetic observations made during the summer and fall of 1911 on board the nonmagnetic yacht Carnegie operating under my direction as Director of the Department of Terrestrial Magnetism of the Carnegie Institution of Washington.

The necessity of the new charts arose from the exceptionally large errors found in the most recent magnetic charts at present in use by mariners. Thus, for example, the errors in the compass directions for two of the most recent charts approximate respectively four degrees and six degrees, though one of them was issued as recently as 1910. With the exception of a few values found by the vessel, the Galilee, used in the Pacific Ocean work, these are the largest errors thus far revealed. In the portions of the Atlantic Ocean thus far covered by the Carnegie the compass chart errors have generally been below two degrees, though running at times up to two and a half degrees.

The chart errors in the compass directions are usually found to be systematic, that is, in the same direction for large stretches, and are to be ascribed largely to erroneous secular changes allowed for in attempting to bring previously observed values up to date.

Thus, for example, by comparing the Carnegie values of 1911 with those obtained on board the German Antarctic vessel, the Gauss, in 1903, it is found that the north end of the compass moved to the eastward (hence diminished west declination) at the average rate of about il' per year off the southeast end of Africa, whereas in the vicinity of the islands of St. Paul and New Amsterdam in the Indian Ocean (lat. 35° 16' S., long. 74° 46' E.) it moved to the westward (increased west declination) at the average rate of about

13' per year. The charts give secular changes of only about one fourth of these amounts, so that the error of reduction in but ten years amounts to almost 2°. It is doubtless due to these large secular changes disclosed in the Indian Ocean, and especially their rapid variation with geographic position, that the large errors mentioned have crept into the charts.

The errors in the other magnetic elements, while of less importance to the mariner, are of consequence to theoretical investigations regarding the earth's magnetism. In the magnetic dip, the errors on the present cruise have amounted at times to 4°, and in the horizontal intensity to about one-twentieth part. While some of the results derived from previous analyses of the earth's magnetic field have pointed to the possibility of large and more or less systematic chart errors, it was not suspected that they would reach the magnitude disclosed by the work of the Galilee and of the Carnegie.

The Carnegie is at present making a circumnavigation cruise and is expected back in New York towards the end of 1913, having left the same port in June, 1910. Up to February 1, 1912, this vessel had already covered about fifty thousand miles. She left Manila on March 23, in command of Mr. W. J. Peters, bound for the Fiji Islands.

Owing to the non-magnetic structure of the Carnegie and the absence in consequence of any deviation corrections, it is possible to obtain and communicate results expeditiously. The data are promptly transmitted to the chief hydrographic establishments issuing magnetic charts in order to enable them to make the necessary corrections from time to time.




(Read April 18, 1912.)

In his Souvenirs intimes sur Talleyrand, published at Paris in 1870, M. Amédée Pichot remarked in his preface:

“If we were to write a complete biography of Talleyrand, we would be able to give some details, very little known, concerning his exile in America, where M. de Beaumetz and he found themselves with other notable émigrés among whom was Moreau de Saint-Méry. ... This information has been obtained from an unpublished diary, kept by Moreau de Saint-Méry, which M. Margry has examined and from which he has communicated to us certain extracts concerning the sojourn of Talleyrand at New York, Boston and Philadelphia."

Pichot made two quotations from this “unpublished diary,” one at pp. 209-212, describing the intimate relations existing between Talleyrand and Moreau, the other at pp. 212-213 giving the text of a letter written by Talleyrand to the French Minister of Foreign Affairs to acknowledge a letter inclosing the decree of September 3, 1795, which reopened the doors of France to the famous exile. Pichot contented himself with these two citations, either because his friend Margryl did not choose to give him more material, or because the limitations of his own study did not permit him to quote more extensively from the notes which were actually communicated to him.

Although many studies have appeared on the life of Talleyrand since 1870 and some have made use of Pichot's citations, apparently none, not even such recent biographers as MacCabe, Lacombe and

· Pierre Margry, author of Mémoires et Documents pour servir à l'histoire des origines françaises des pays d'outre-mer” and of some studies relating to the history of French colonization in America, was at this time archivist at the Ministry of the Marine.

Loliée, have attempted to find the source from which the citations were taken to see whether it contained other interesting material upon the sojourn of the great diplomat in America.

It was my good fortune, a little over a year ago, to find in the manuscript catalogue of the Archives Coloniales at Paris, the title, “Le Voyage aux Etats-Unis de l'Amérique par Moreau de SaintMéry pendant les années de 1793 à 1798.”

Although it called me far afield from the work in which I was engaged, I could not resist the temptation to cast a furtive glance at the manuscript to see what its interesting title meant. That furtive glance grew into the absorbing task of reading from page to page until I had finished the story which the volume contained a story all but forgotten and lost for three generations among the dusty archives of the Colonial Office. It is to this story that I wish to direct your attention for a few moments.

With the author of the diary many of you are already acquainted from the paper which one of your members presented before this society at its last annual meeting.* Permit me to recall, however, the salient facts in his life.

Born at Fort Royal, Martinique, on January 13, 1750, MédéricLouis-Elie Moreau de Saint-Méry was of a family which had emigrated from Poitou to settle at Martinique in the seventeenth century and had won a place of prominence by furnishing in succeeding

MacCabe,“ Talleyrand, a Biographical Study,” London, 1906; Bernard de Lacombe, “La vie intime de Talleyrand,” Paris, 1910; Frédéric Loliée, “ Talleyrand et la société française," Paris, 1910.

Victor Tantet, late archivist of the Archives Coloniales, made use of the diary to write a very interesting article which appeared in La Revue (1905), Vol. 52, pp. 378-396, and entitled “Les Réfugiés politiques français en Amérique sous la Convention-Moreau de Saint-Méry libraire à Philadelphie." I knew nothing of the existence of this article until after I had found and studied the diary.

* Joseph G. Rosengarten, “Moreau de Saint-Méry and his French Friends in the American Philosophical Society," Proceedings of this Society, Vol. 50, pp. 168–182.

* This short sketch of Moreau is based on Silvestre, “Notice Biographique sur M. Moreau de Saint-Méry,” Paris, 1819 (a short pamphlet of 24 pp.), and Fournier-Pescay's article in Biographie Universelle on Moreau de SaintMéry.

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