first compartment 22 the partition 21 has an axial through hole 26 which axially passes through the cylindrical ridge 25 and the annular flange 24 the hole 26 has at the top a conical profiled substantially tapered zone 26 u2032 with an increasing diameter as compared to the lower zone an internal thread 27 is provided in the internal surface of the container body 20 within the end 2 a of the first compartment 22 as seen in fig3 the first cap 4 according to the present invention comprises a body consisting of a substantially cylindrical middle zone 40 with an external diameter substantially equal to the external diameter of the container body 20 a dome shaped upper zone 41 placed above the middle zone and a substantially cylindrical lower zone 42 provided with an appropriate thread 45 adapted to be fitted in the corresponding thread 27 provided within the end 2 a of container 2 a knurl 44 consisting of a plurality of ribs and grooves is provided on the external surface of the middle zone 40 of the body of the upper cap 4 a shank or stick 46 presenting a first substantially cylindrical section 47 with a diameter d 1 smaller than the diameter of the lower zone.