body portion of the bottle does not contain the reservoir many shapes could be used including an ellipse circle rectangle or any other shape the cross section of the body portion of the bottle has an inside and outside area in a preferred embodiment the cross sectional area of the reservoir is less than half that of the inside cross section of the body of the bottle in another preferred embodiment the cross sectional area of the reservoir is less than u00bc of the inside cross section of the body of the bottle in another preferred embodiment the cross sectional area of the reservoir is less than u215b of the inside cross section of the body of the bottle however other ratios can be used as long as the cross sectional area of the reservoir is less than the inside cross sectional area of the body of the bottle for example if the inside cross sectional shape of the body portion is an ellipse the cross sectional area would be calculated using the formula where r5 and r6 represent the short and long radii of the ellipse see fig8 b if the short and long radii are equal the shape is a circle and the area is calculated using the formula in another example the inside.