on the container 12 and deforms it in order to deliver a droplet of liquid under the pressure exerted by the user the valve 20 switches from the liquid blocking position to the liquid release position a droplet is formed in the droplet forming means 50 when the droplet reaches a predetermined volume it is released from the valve 20 for example to go into the eye of the user as soon as the user relaxes the pressure exerted on the container 12 the valve 20 reverts to its liquid blocking position when the user wants to deliver an additional droplet he or she once again deforms the container 12 until the droplet is delivered however a small quantity of liquid may remain downstream of the valve 20 often in the droplet forming means 50 between two uses the user rescrews the cap 16 onto the end piece 14 the locking means 64 66 84 86 then prevent the displacement of the outer jacket 42 relative to the inner jacket 44 it will therefore be understood that it is possible to switch from the hermetic sealing configuration of the device 10 to the ventilation configuration but the reverse is not possible thus there is a guarantee that once the device 10 has been used at least once the evaporation path 90 for the residual liquid is always open the locking means 64 66 84 86 are therefore permanent and non removable when the cap 16 is screw mounted on the end piece 14 the expulsion shape 46 of the valve cooperates with the valve 20 furthermore this expulsion shape 46 comprises grooves 92 which delimit with the valve 20 an evacuation pathway 52.