In explanation of this experiment, M. Hachette says, “The air is pushed from the mouth A of the tube, towards the orifice E of the plate; it strikes the part of the disk opposed to this orifice, and the mean pressure on that part is greater than the pressure of the atmosphere. The blown air then takes place of that between the plate and the disk opposed to it; it moves in this interval with a velocity decreasing from the edges of the aperture: the elastic force of this air decreases at the same time, so that its mean pressure between the plate and the inner face of the disk becomes less than the atmospheric pressure; and as this last pressure is exerted on the whole external face of the disk H, I, this disk, subject at the same time to the two contrary pressures on its opposing faces, obeys the greater, and is pushed towards the plate C D.” “It is not necessary that the disk, C D, should be near the orifice E, of the tube A E. Let _Fig._ 2 be an instrument composed of a hollow cylinder, C D F G, and a flat border of the dimensions C″ F, or G D″. Let a tube, A E, be fixed to the bottom of the cylinder, the orifice E having a diameter of about three millimeters (0.12 of inch). If air be blown in at A, against the disk, H I, in the neighbourhood of the flat border, the disk will be urged towards the orifice E. This instrument is also delineated on a scale of one half. The disk, with the attached weight, weighs about 12 grammes (184.87 grains), being 54 millimeters in diameter; the pressure of the atmosphere upon it equals 23 kilogrammes: from which it follows that, in this experiment, the pressure of the air blown upon the inner surface of the disk, and the atmospheric pressure exerted on the exterior of the same disk, only differs from each other by about one two-thousandth part of the latter.”—_Annales de Chimie_, xxxv. 34. FOOTNOTE: [34] See the last volume of this Journal, p. 473. 2. _Considerations relative to Capillary Action, by_ M. Poisson.—M. Dutrochet, whilst explaining his views relative to the cause of vital movement in plants and animals, stated that if an animal or vegetable membrane were formed into a bag, having a tube of [p195] glass attached to its aperture, and were then filled with a liquid substance, having a strong affinity for another liquid, into which the bag was to be immersed, it would not only have the power of absorbing the latter liquid into its pores, but also, in certain cases, of forcing it up to the top, and even out of the glass tube held in a vertical position. On this point, a difference of opinion with regard to the force of capillarity took place: M. Ampère maintaining that capillary action would raise the fluid to the top of the tube, but not cause its expulsion; while M. Poisson maintained that, in certain cases, the latter effect could be produced. The latter has since then published a note, which we transcribe in part, from the _Annales de Chimie_, xxxv. 98.