Salt Depot™ Purple Heat® PH50 50 lb Bag Ice Melter. Salt Depot™ is the original manufacturer of this Best Seller! Well known across the US as the “Purple Stuff;” Purple Heat is a magnesium chloride blend and will melt down to -15ºF / -26ºF. It contains a purple, organic, non staining dye for controlled application. Purple Heat® is safer on concrete and is pet and environmentally friendly with suggested application.