Societies and Academies

Abstract

PARIS Academy of Sciences, October 11.—M. Wurtz in the chair. The following papers were read:—On the rôle of time in the formation of salts, by M. Berthelot. Experiments with several hundred saline mixtures prove that the period of change in saline reactions, comprised between the moment when the system has become physically homogeneous and that when it attains its chemical equilibrium, is excessively short, and wholly included in the short duration of the calorimetric experiment. The same period in ethene reactions, on the other hand, is incomparably longer. The instantaneity in the former case is proved by an application of the author's theorem of slow actions.—On pellagra in Italy, by M. Faye. In the past year there have been 40,000 well-marked cases of the disease in Lombardy, and 30,000 in Venetia, the richest and most productive provinces in Italy. It is unknown in Naples, Sicily, and Sardinia (so poverty and bad hygiene do not seem to be the causes). Wherever pellagra appears in the endemic state polenta or cruchade are eaten, i.e., varieties of unfermented bread (made from maize and millet), and M. Faye thinks the substitution of fermented bread would prove salutary.—On the photophonic experiments of Prof. Bell and Mr. Sumner Tainter, by M. Breguet.—On algebraic equations, by Mr. West.—Earthquakes at Smyrna on July 29, by Dr. Charpentin. The ravages and phenomena of this earthquake were limited to the Sipyle chain and the adjoining plains in a perimeter of only a few leagues; but the contre-coup was felt at great distances (Broussa, Rhodes, &c). Chronometers at Athens were stopped. More than 3,000 years ago there seems to have been a volcano under Sipyle, and this point has been the centre of earthquakes in that region. The approximate coincidence (in time) of this last Smyrna earthquake with earthquakes at Manilla, the Azores, and Naples, is remarkable.—On the effects produced by cultivation of absinthe as insectifuge, and on its preventive application against phylloxera, by M. Poirot. Among the absinthe plants covering large tracts in North America the author has never seen flies, ants, worms, or any insects, nor yet scorpions, tarantulas, nor rattlesnakes. Land manured with absinthe might be fatal to the metamorphoses of phylloxera.—Ephemerides of comet b 1880 (continued), by M. Bigourdan.—Observations of comet d 1880 (discovered by Dr. Hart wig at Strassburg) at the Paris Observatory, by M. Bigourdan.—Oh the resolvent function of the equation xm + px + q = o, by M. Pujet.—On a property of Poisson's function, and on the integration of equations with partial derivatives of the first order, by M. Gilbert.—On a very extensive class of linear differential equations with rational coefficients, whose solution depends on the quadrature of an irrational algebraic product, by M. Dillner.—Principle of an algebraic calculus which contains as particular species the calculus of imaginary quantities and quaternions, by M. Lipschitz.—On the partition of numbers, by M. David.—On the mechanical actions of light, theoretical considerations capable of serving in interpretation of Prof. Bell's experiments, by M. Cros. In 1872 M. Cros presented a memoir to the Academy, in which, guided by theoretical considerations, he affirmed à priori the results of experiments which he thinks have a notable similarity to Prof. Bell's. In one experiment a ray of light interrupted n times a second was to be sent into a tube resonating with a note of n vibrations. The alternate rarefaction and condensation of the gaseous medium might make the tube speak.—Study of the distribution of light in the solar spectrum, by MM. Mace and Nicati. The maximum intensity is in the yellow, very near D. The perception of blue and violet diminishes much more slowly with diminished illumination than that of less refrangible colours. From the extreme red to green of about 0.5 μ wave-length, the law of distribution of intensity is the same whatever the illumination. Between eyes equally capable of discerning colour, there are very sensible differences.—Vibratory forms of circular pellicles of sapo-saccharic liquid, by M. Decharme. With a given diameter of pellicle the numbers of nodals are inversely proportional to the corresponding lengths of the vibrating rod (which produces the waves).—On the place which boron occupies in the series of simple bodies, by M. Etard. He places boron in the family of vanadium, very near that of phosphorus.—On propylacetal and isobutylacetal, by M. de Girard.