References.—Humboldt, “Cosmos,” London, 1849, Vol. I. pp. 108–109; Young, “Course of Lectures,” London, 1807, Vol. II. p. 501, alluding to “Zach. Mon. Corr.,” VI. p. 276, also to Gilbert, XIII. p. 353, 108, and stating that Olbers had suggested Laplace’s idea in 1795. See “Mem. of the Astronom. Soc. of London,” Vol. III. p. 395: Laplace, “Mem. de l’Institut” for 1809, p. 332; Dr. Young’s “Course of Lectures,” 1807, Vol. I. pp. 249, 250, 522; Vol. II. p. 466; Humboldt, “Cosmos,” London, 1849, Vol. I. pp. 28, 76, 130; Vol. II. p. 712; Lavoisier at A.D. 1781: Biot at A.D. 1803; Annal. de Ch. et Phys., Vol. XV. pp. 72, 73, and for Laplace and Lavoisier, see Delaunay, “Manuel ...” 1809, p. 178; “Mem. de l’Acad. des Sc.,” for 1781; “Journal des Savants,” for Feb. 1850 and Nov. 1887; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 184; “Cat. Sc. Pap. Roy. Soc.,” Vol. III. pp. 845–848; Johnson’s “Cyclopædia,” pp. 1647–1650 and the “First Supplement,” p. 62.
For Laplace and Joseph Louis Lagrange, see “Mémoires de l’Institut,” Vol. III. p. 22; also “Pioneers of Science,” by Sir Oliver Lodge, London, 1905, Lecture XI, and for Lagrange, consult “Journal des Savants,” Sept. 1844, May 1869, August 1878, Sept. 1879, Sept. 1888 and Oct. 1892.
M. Cyrille Pierre Théodore Laplace, captain in the French navy, is the author of the “Voyage Autour du Monde ... sur la Corvette Favorite ...” and of “Campagne de Circumnavigation de la Frégate l’Artémise ...” published in Paris during the years 1833, 1839 and 1841.
Baron Jean Baptiste Fourier, celebrated French physicist (1768–1830) who, in 1827, succeeded Laplace as head of the Council of the Ecole Polytechnique (“Biog. Gén.,” Vol. XVIII. p. 346) says of his predecessor:
“Posterity, which has so many particulars to forget, will little care whether Laplace was for a short time minister of a great state. The eternal truths which he has discovered, the immutable laws of the stability of the world, are of importance, and not the rank which he occupied” (C. R. Weld, “Hist. Roy. Soc.,” Vol. II. p. 465). Fourier is the author of “Expériences thermo-électriques” (“Encycl. Brit.,” ninth ed., Vol. IX. p. 490; “Eng. Cycl.,” Biography, Vol. II. p. 977).
A.D. 1820.—Dutrochet (René Joachim Henri) (1776–1847) a distinguished French natural philosopher, and likewise medical adviser to the King of Spain, Joseph Bonaparte, publishes an interesting treatise on meteors, in conjunction with Mr. Nathaniel Bowditch, who had already written many very able papers on astronomical subjects and who afterwards translated the “Mécanique Céleste” of Laplace. Eight years later (1828) appeared Dutrochet’s “Nouvelles Recherches ...” wherein he attributes to electricity the direction taken by fluids through animal and vegetable membranes. The passage of a fluid from without inwardly he called endosmosis, and the passage of the fluid from within outwardly he termed exosmosis.
Of Dutrochet, Dr. John Hutton Balfour, of Edinburgh, makes mention when treating of the temperature of plants. He thus expresses himself: “While the nutritive processes are going on in the plant, there is a certain amount of heat produced. This, however, is speedily carried away by evaporation and other causes, and it is not easily rendered evident. Dutrochet, by means of Becquerel’s thermo-electric needle, showed an evolution of heat in plants. In doing this, he prevented evaporation by putting the plant in a moist atmosphere. In these circumstances the temperature of the active vegetating parts, the roots, the leaves, and the young shoots, indicated a temperature above the air of ½ to ¾ of a degree Fahrenheit. Van Beek and Bergsma, in their experiments on the Hyacinthus Orientalis and the Entelea Arborescens, found the proper heat of the active parts of plants about 1·8° F. above that of the air. The vital or proper heat of plants, according to Dutrochet, is found chiefly in the green plants, and it undergoes a quotidian paroxysm, reaching the maximum during the day, and the minimum during the night. When stems become hard and ligneous, they lose this vital heat. Large green cotyledons gave indications of a proper heat. The hour of quotidian maximum varied from 10 a. m. to 3 p. m. in different plants.”
It is stated by Becquerel that in the act of vegetation, the earth acquires continually an excess of positive electricity, while the bark and part of the wood receive an excess of negative electricity. The leaves act like the green part of the parenchyma of the bark—that is to say, the sap which circulates in their tissues is negative with relation to the wood, to the pith, and to the earth, and positive with regard to the cambium. The electric effects observed in vegetables are due to chemico-vital action, and he asserts that the opposite electric states of vegetables and of the earth give reason to think that, from the enormous vegetation in certain parts of the globe, they must exert some influence on the electric phenomena of the atmosphere.
References.—Gmelin’s “Chemistry,” Vol. I. p. 447; “Biog. Gén.,” Vol. XV. p. 506; Poggendorff, “Annalen,” Vol. I. p. 663; Larousse, “Dict. Univ.,” Vol. VI. p. 1448; J. W. Ritter, in “Denkschr. d. Münch. Acad.” for 1814, and the eighth ed. of the “Ency. Brit.” Vol. XXI. p. 635, for observations concerning the mimosa pudica and the mimosa sensitiva; “Cat. Sc. Papers Roy. Soc.,” Vol. II. pp. 422–425; Vol. VI. p. 646; Vol. VII. p. 584; Poggendorff, Vol. I. p. 633; “Observations on the diurnal variation of the magnetic needle,” in Sturgeon’s “Annals,” Vol. VII. pp. 369–370, and in the Comptes Rendus, Vol. XII. p. 298, of Feb. 8, 1841; Burnet, “On the motion of sap in plants. Researches of Dutrochet on Endosmose and Exosmose ...” London, 1829 (“Phil. Mag. or Annals,” Vol. V. p. 389).
A.D. 1820.—Fresnel (Augustin Jean) (1788–1827), one of the most distinguished French mathematicians and natural philosophers, communicates a paper detailing his experiments for decomposing water by means of a magnet. He produced a current in an electro-magnetic helix enclosing a bar-magnet covered with silk, and on plunging the ends of the wire in water he observed some very remarkable effects which are set forth in the Annales de Chimie et de Phys., series 2, Vol. XV. p. 219.