physiological saline or ordinary tap water.
safe to swim in and tap water is potable.
Thus, a shallow tin vessel, such as the lid of a biscuit box, may be levelled and filled with tap-water through a rubber hose.
This evidence appears to contradict the assumption that tap water should only be considered in heavily colonized environments.
In the case of the fountain the experiment may be made by leading tap-water through a Woulfe's bottle in which a little milk has been placed.