Here is the full list of all 17 Liquid Pinball achievements.
Complete stage I
Lose a fluid in black hole
Lose a fluid over the edge of the field
Learn how to make green fluids
Learn how to make violet fluids
Learn how to make red fluids
Learn how to make blue fluids
Keep the water unpainted
Complete stage II
Complete stage IV
Complete stage V
Complete 12 levels with 1 star or more
Complete 24 levels with 2 stars or more
Complete 48 levels with 3 stars or more
Skip single level with gems