Magnesium sulfate / potassium sulfate / sodium sulfate
"One of the nastiest things I've ever tasted!  Very "caustic" and a little salty.  I drank both "steps" in a single swig, then immediately brushed my teeth because of the awful after-taste.   The prep worked well, causing relentless diarrhea.   I could not even count the bowel movements I had, lasting for about 4 hours after each dose.  I'm sure I was VERY cleaned out.   Worst part of the whole experience was the severe anal burning."