The present invention relates to a diffuser of volatile substances, including: - an installation comprising two pipes and in which circulates in closed circuit, a liquid composition of perfume and / or sanitising base, - a stopper - double (3) consisting of two side pieces (3a, 3b) connected head to tail, -, each of said end fittings (3a, 3b) comprising a connection end (4a, 4b) making it possible to connect said plug (3a, 3b) to one of the ducts so that the liquid composition (2) flows through the stopper - double (3), characterized in that: - the stopper - double (3) is carried out in a piece of wood, which is adapted to be impregnated with the liquid composition in the flow of the latter to the inside of said stopper - double (3), which composition liquid evaporates in the form of a volatile substances in contact with the ambient air, - the stopper - double (3) incorporates a conduit (6) through which flows the liquid composition, which conduit (6) comprises: a central channel (60) provided with two ends (6a, 6b), • of the conical cavities (60a, 60b) arranged in each of the connectors (3a, 3b), each conical cavity (60a, 60b) having its apex, which is adjacent to one of the ends of the channel (60) and its base, which is adjacent to the connection end (4a, 4b) associated with the endpiece (3a, 3b), in which the cavity (60a, 60b) is arranged, a seal (15a, 15b) placed in each of the connection ends (4a, 4b) so as to ensure a seal between the stopper - double (3) and the containers (1a, 1b).
