1. Preheat grill to medium-high heat.
2. Pull the husks back from corn, keeping husks intact; scrub off silks, and pull husks back over corn to cover. Place corn and salt in a large stockpot; cover with water. Let stand 45 minutes; drain.
3. Place corn on grill rack, and grill for 8 minutes on each side or until husks are blackened. Serve grilled corn with butter.