CREATE TABLE table_18450 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

In what district is the incumbent John Bell Williams?
SELECT "District" FROM table_18450 WHERE "Incumbent" = 'John Bell Williams'
SELECT "District" FROM "table_18450" WHERE "Incumbent" = 'John Bell Williams'