180 MEMOIR OF OERSTED. 



most eminent practical chemists, and obtained, after prolonged efforts, tlie clilo- 

 ride of aluminum. No one before him had effected the decomposition of alu- 

 mina. Yet he did not succeed in insulating the aluminum ; this last and import- 

 ant step was reserved for M. Vohler, the distinguished chemist of Gottingen, 

 Still later, our young and learned colleague, M. Henri Sainte-Claire Deville, 

 has formed of aluminum a new and valuable element of metallurgic industry. 



One of the last labors of Oersted relates to the celebrated diamagnetic dis- 

 coveries of our illustrious colleague M. Faraday, whose experiments had already 

 added so many curious facts to electro-magnetism, as well as to the researches 

 made on the same subject by some German savants, especially by M. Reich, of 

 Friburg. 



Oersted presented his first results to the Royal Society of Sciences of Copen- 

 hagen, 30th June, 1848, and gave a review of them- in the Compie Bendu of the 

 transactions of the society. He soon afterwards drew up a more complete 

 memoir, which has been published in French.* Therein he recognizes a decreas- 

 ing magnetic progression which includes the magnetic bodies properly so-called, 

 the attractable diamagnetic bodies, the repellable diamagnetic bodies. The 

 magnetism of these last may, according to him, be considered as negative, if we 

 regard the magnetism of iron and of the attractable diamagnetic bodies as posi- 

 tive. Oersted showed herein that, experiment in hand, he always kept himself 

 abreast of the progress of physics, and particularly of electro-magnetism. 



In effect, the weight of years never relaxed the activity of Oersted. Were I 

 to undertake a bare enumeration of the researches and writings of every kind 

 which he executed at Copenhagen during the last twenty-five years of his life, 

 I should much exceed the time at my disposal. But, while omitting this long 

 catalogue, in which are numbered nevertheless important memoirs on electricity 

 and magnetism, on the compressibility of liquids and of gases, on the heat 

 developed by the compression of water, on capillary phenomena, works of liter- 

 ature and philosophy, &c.,t I feel bound to point out what contributed in quite 



* See Annales de Chimie. et Physique, 3d series, t. xxiv, p. 424, (December, 1848.) 



t The following note, for which I am indebted to M. de la Roquette, makes us acquainted 

 with one of tliese last Works : 



"Oersted published, about 1850, two volumes under the title of Aanden i Naturen, a 

 philosophic work which appears to me of high import ; it forms a series of treatises in which 

 the author introduces us, in a manner at once philosophic and popular, to the study of 

 nature, by revealing: to lis the eternal spirit which determines all its phenomena, and the 

 relation under which this spirit exists towards the material and intellectual world. The 

 following is the substance of the tracts or chapters of which the work is composed : 



" Vol. I. (1) Of spirit manifested in matter. The author develops what is constant or 

 immutable in the continual changes of bodies ; it is the single thought or design which 

 exists therein. The unity of this thought pertains to nature, for the natural laws, which are 

 constant au3 invariable, are laws of reason; not of the reason which is in us, but of that 

 which prevails in the entire universe. It is the assemblage of laws determining the activity 

 of an object, which constitutes its real essence. These laws, which may be properly called 

 the ideas of nature, form in every object a unity which may be qualified as the essential 

 meaning of the object or its idea. This idea does not exist solely in the thought ; it is real- 

 ized, on the contrary, in the acting forces of the objects. The being of the object is thus an 

 animated or living idea. lu order to place these interesting reflections within the reach of 

 all, the author has recourse to the form of dialogue, like Plato, Fonteuella and Fenelou; his 

 style is at once simple and clear, rich and varied. (2) The fountain and the jet d'eau. 

 He here characterizes the different impiessions produced by this phenomenon. (3) The 

 relation between the conception of nature by thought and that which is efl'ected by help of 

 the imagination. (4) Superstition and incredulity in their relations to the natural sciences. 

 (5) All existence considered as the empire of spirit. (6) The culture of the sciences rep- 

 resented as a worship offered to God. 



" Vol. II. (1) The relation of the natural sciences to poetry. (2) The relation of these 

 sciences to different important notions of religion. (3) Of" the salutary influence which the 

 study and employment of the natural sciences must exert on the intellectual development of 

 man. (4) Two discourses on occasion of the reunion of the Scandinavian naturalists. (5) 

 On the passage from the school to active life. (6) Comparison of ancient and modern 

 times ; the author here demonstrates that neither the world uor humanity have deteriorated ; 

 that the temperature of the air has not changed ; (the physical state of Greenland was, six 



