PARIS. Academy of Sciences, October 3.—:M. Mascart in the chair.—A comparison of the expenditure of the flexor and extensor muscles of the forearm, applied, each group separately, to the production of the same continuous external work: A. Chauveau. The energy expended was measured by means of the respiratory coefficient. It was found that the external work effected by the flexor muscles of the forearm was less than that of the extensors, the proportion being about 0.4 for the former and 0.6 for the latter. This difference appears to be due exclusively to the less favourable conditions under which the extensor muscles work.—On the loss of electricity in air in the neighbourhood of thermal springs: A. B. Chauveau. In the thermal springs at Cauterets, the radio-activity of the air near the spring was clearly marked, the loss observed in the neighbourhood of the reservoir being three times as fast as in the open air.—The colorations produced by the Becquerel rays; its application to crystallography and to the calorimetric determination of radio-activity: C. J. Salomonscn and G. Dreyer. The coloration produced by radium on certain crystals demonstrates the zonal structure of the crystal, and thus throws light upon the manner in which it has been built up. In the case of quartz, this zonal structure has not hitherto been demonstrated.—On a vacuum effect produced by a waterspout: Léon Pigeon.—On actinium: A Debierne. The substance previously described by the author under the name of actinium presents many similarities with the emanium of Giesel. The opportunity has recently arisen of directly comparing the two substances, and the observations of M. and Madame Curie, M. Giesel, and the author on the characteristic phenomena of phosphorescence provoked by the two products shows that they are identical. The name emanium should therefore be dropped in favour of the earlier actinium.—The properties and constitution of the molybdenum steels: Léon Guillet. The series of steels studied contained only 0.2 per cent, of carbon, with molybdenum increasing from o per cent, to 15 per cent. A second series contained about 0.85 per cent, of carbon. In small quantity, molybdenum increases the breaking load without causing extra fragility. The general properties of the molybdenum steels resemble those of tungsten steels, but four times as much molybdenum as tungsten is required to produce the same results.—A thermochemical comparison between rosanilines and leucanilines: Jules Schmidlin.—On the morphology of the Chetoptera: Ch. Gravier.—The archaic form of the Thecosome Pteropods: Paul Pelseneer.—On the structure of the muscles of Anomia ephippium: F. Marceau,—On acarophytism in Monocotyledons: E. de Wildman.—Semeiology of the prostatic secretion: A. Guépin.—On a new treatment of seeds: E. Bréal and E. Giustiniani.