Washing soda from baking soda

1. Heat a box of baking soda in oven or toaster oven for at least 30 minutes at 400F (45 minutes should finish the work)
2. You will know it converted to washing soda when you take a fingertip amount of the washing soda and feel it under running water - it will dissolve and feel very slippery while baking soda is gritty and takes a couple seconds before it dissolves
3. Store in a container