Citric Acid is commonly used in making bath fizzies.
RECIPE: Bath Bombs
Here is a basic Bath Bomb recipe
2 Cups bicarbonate of soda
1 cup citric acid
1 Cup Cornflour/Cornstarch
Sieve all ingredients well EXCEPT the colour
3 T Polysorbate 20
1 t water
10ml fragrance or essential oil
Add water to the colour then combine all other liquid ingredients and shake well together. Drizzle onto dry ingredients and mix well together.
Pack balls of mixture tightly into Moulds remove carefully. Place balls onto flat surface to dry out over night. Package Fizzballs into shrink wrap or bags or fizz ball holders.