We're celebrating a #summerofscience and the release of Investigate Box 4: Rocket Fuel with a sneak preview! Red cabbage juice makes a brilliant pH indicator, changing pink in the presence of acids and blue in the presence of alkalis. We provide plenty of cabbage juice indicator in Box 4 but if you can't wait you can make your own by chopping and boiling a red cabbage for a few hours and sieving.
