Volumetric device for distributing powder with a view to spraying it by means of a current of air in which the powder thus distributed falls under the effect of gravity alone. The invention comprises a rotating instrument 12 which carries at its periphery blades 3 which are thus set in rotation at the base of the hopper 1, which contains the powder, and which convey, between each of them, a constant quantity of powder as far as the vertical of a calibrated hole 2, of adjustable area, from where the powder falls by gravity in the current of air which sweeps the inner and outer surfaces of the said hopper 1. The invention may be used for agricultural treatment as well as in apparatuses carried on a tractor, drawn by a tractor, or carried on light aircraft of the powered microlight type. <IMAGE>
