Paris Peacock (Papilio paris)--- a common swallowtail.
Glassy Bluebottle (Graphium cloanthus)---- a rare swallowtail
In fact this behaviour is not intended to satisfy their thirst but to obtain minerals which are essential for reproduction. Most of the water drinking butterflies are male who then transfer the nutrients to the female through their sperm to improve the quality of her eggs.
Actually in addition to nectar, many butterflies also rely on other sources of liquid for food. I saw this Red Ring Skirt (Hestina assimilis, Nymphalidae) enjoying tree sap on a Pomelo tree.
When the dinner was finished, the precious proboscis was carefully curled up for a well deserved rest.
More photos at Google+