the outlet 26 ensures that there is no leakage of the additive 7 into the product in the product reservoir 3 also this ensures that there is no inadvertent discharge of the additive 7 where the outlet 26 is sealed prior to purchase of the product and the plunger column 19 is initially separate from the plunger 9 a tip portion of the plunger column 19 may be fabricated in such a manner so as to provide a seal for example the tip portion may include a rubber gasket or some such similar material to facilitate sealing the outlet 26 in the closed state also the tip portion is formed in such a manner as to readily engage with a plunger 9 in the dispenser 4 for dispensing the additive 7 as discussed below as also seen in fig2 the plunger 9 is provided inserted in the inner reservoir at a lower most portion thereof i e closer to the base 23 of the bottle 1 than the outlet 26 of the dispenser 4 so that the additive 7 is substantially contained in the additive reservoir 5 between the outlet 26 and a nose 31 of the plunger 9 when it is desired for a certain amount of the additive 7 to be added to the liquid in the main reservoir the cap 17 is removed from.