be in the form of a gel paste emulsion viscous dispersion viscous solution or dispersed or dissolved in water immiscible liquid s provided that the additive in the form selected is capable of being dissolved or dispersed into the cistern water at an appropriate rate the additive itself may be a variety of substances present singularly or in combination these include dyestuffs fragrances disinfectants deodorants and the like depending on the nature of these substances they may be dissolved or dispersed into the water contained within the first chamber the dispenser may be sold with or without the additive present in the chamber additive may also be sold separately to allow for replacement once the additive in a dispenser is used up the volume of additive containing water dispensed will be determined by a number of factors excluding the volume occupied by the additive in solid form these are a the extent to which the dispenser is immersed which will in turn determine the level of water in the chambers b the volume of the second chamber below the level of water therein and c the volume of the first chamber defined between the height of the second wall and the level of the water therein it is preferred that.