1.In A Small Bowl, Mix Together Black Pepper, Paprika, Chili Powder, Celery Salt, Cayenne Pepper, Garlic Powder, And Mustard Powder. Rub Mixture Over The Surface Of The Meat. Place Roast In A Slow Cooker, And Add 1/2 Cup Water. 2.Cover, And Cook On Low For 8 To 10 Hours. When Meat Is Tender And Well Done, Transfer Roast To A Serving Platter. Skim Fat From Juices, And Strain; Serve With Meat.