non complementary fragrance has a different pattern which does not match the pattern of either of the containers in fig3 thus if a container including a non complementary fragrance is used with one of the containers illustrated in fig3 the lack of matching pattern will be readily apparent it will be appreciated that this effect need not be provided by a raised pattern inset patterns may be used or simply print effects another possibility is provided by the arrangement of fig3 in this figure one side surface 97 a of one container 88 a has a non planar shape which is complementary with a non planar shape of the side surface 97 b of the other container 88 b containing a complementary fragrance so that the side surfaces 97 a 97 b interlock when the containers 88 a 88 b are placed side by side in the housing 10 containers holding non complementary fragrances are provided with different side surface configurations and so will not be able to interlock and will thus not be able to be used the use of a fan to disperse fragrance need not be confined to the dispersal of two fragrances referring next to fig3 a fourth form of fragrance disperser is formed by a.