passages 2 a and 3 a of the discs 2 and 3 flows into an annular channel defined between the disc 3 the member 4 and the sliding member 6 passes through the space between the disc 3 and the sliding member and reaches the interior of the sliding member 6 in the region of the base of an internal chamber 6 a of that sliding member at the same time cold water enters the cartridge via the pipe 1 b as indicated by the arrow f b passes along the passages 2 b and 3 b of the discs 2 and 3 and after being discharged radially from the lateral passage 3 b of the disc 3 flows into an annular channel 4 c which is defined between at one side the lower portion 4 a of the member 4 and at the other side the casing 1 then the stopper 8 in order to reach the upper portion of the sliding member 6 and pass via the space between the sliding member and the upper portion 4 b of the member 4 before being introduced into the upper portion of the chamber 6 a the mixing of the hot water and cold water begins inside the chamber 6 a and continues inside the passages 2 c and 3 c which extend in a symmetrical manner relative to the joining plane p and which are therefore completely in fluid communication in other words the entirety of the passage 3 c is in fluid communication with the entirety of the passage 2 c and the cross section s of flow of mixed water is therefore equal to the whole of the cross section of the passage 3 c which is itself equal to that of.