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128 has been almost exclusively devoted to the novel and remarkable electro-capillary phenomena first observed by him in 1867. These can be observed in their simplest form when a cracked test-tube containing a solution of cupric sulphate, for example, is immersed in a solution of sulphide. A deposition of metallic copper takes place at once on the crack. This elementary fact has been elaborated in a variety of directions with numerous solutions, and the laws regulating the development of electric currents by capillary action partially enunciated. The study of these phenomena is, however, still in its infancy. Becquerel regarded them as explanatory of the deposition of metals in veins in the rocks and of many physiological reactions taking place in the vegetable and animal tissues. A very detailed account of the experiments is to be found in vol. xxxvi. of the "Mémoires de l'Institute."

Despite his manifold experimental investigations, Becquerel was an indefatigable author, and contributed a most valuable series of standard works to the physical literature of the past forty years. In the seven volumes of his "Traité expérimental de l'Electricité et du Magnétisme, et de leurs Phénomènes naturels," 1834-40, he presented these two sciences with a completeness and systematic arrangement which has been hitherto wanting in physical literature. This work was followed by "Eléments d'Electro-Chimie appliquée aux Sciences naturelles et aux Arts," 1843; "Traitée de Physique considérée, dans ses Rapports avec la Chimie," 1844, 2 vols; "Eléments de Physique terrestre et de Météorologie," 1847; "Traité de l'Electricité et du Magnétisme; leurs Applications aux Sciences physiques, aux Arts, et à l'Industrie," 1856, 3 vols.; "Resume de l'Histoire de l'Electricité et du Magnétisme," 1858; and "Des Forces physico-chimiques et de leur Interprétation dans la Production des Phénomènes naturels," 1875.

In 1829 Becquerel was elected a member of the French Academy, and received in 1874 the medaille cinquantenaire, although he had been but forty-five years a member. His scientific communications are to be found in the "Comptes Rendus" of the Academy and in the "Annates de Chimie et Physique." The Royal Society elected him as a corresponding member a number of years ago, and he was one of the three French savants who have been recipients of the Copley medal. In 1865 Napoleon III. decorated him with the cross of commander of the Legion of Honor.

Prof. Becquerel leaves behind him a son, Edmond Becquerel, professor of physics in the Conservatoire des Arts et Métiers, who has assisted his father for a long series of years in the compilation of his numerous works, and whose researches in electricity fairly rival those of the latter. The funeral ceremonies took place on Monday in the church of St. Medard, at Paris.

 

 . — On reading the article which appeared in Nature, vol. xvi., p. 451, on the heat phenomena accompanying muscular action, it has occurred to me to send the following problem which is akin to the subject.

If a man does work (say lifts a weight), the principle of the conservation of energy teaches us that the potential energy — the work done — (weight lifted) is at the expense of the man as a magazine of force, in fact that "virtue has gone out of him." Now suppose a man lifts say a ton of bricks and deposits the bricks one by one on the top of a wall six feet high, we can exactly estimate the amount of work done, the energy rendered potential and external, and if we knew also the extra amount of heat radiated or otherwise carried off from his body — as most probably the work would raise his temperature — we could exactly measure the amount of energy the lifting of the brick cost him.

Now suppose another man were to lift the bricks from the top of the wall and deposit them gently — i.e., without concussion — on the ground, it is evident that there is a certain amount of potential energy disappearing, in fact that there is work being absorbed by the man, of course appearing in some other form, but the question is how? This second man's work is of course in one sense work, but in the sense of producing external, potential, or kinetic energy, is not so, unless, perhaps, in heat.

Strangely enough it follows that lifting down the brick ought to make the man either radiate heat more, waste tissue less, digest food less, or in some other way account for the energy absorbed by him.

Generally I think the conversion of force by obstruction is not always so clearly traced as it might be; in friction it is clear, as also in the compression of elastic bodies, but in the instance above, as also in the throttling of steam, it is not so clear. Nature.