CREATE TABLE table_6558 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB)

Which District has a First elected of 1856, and an Incumbent of william kellogg?
SELECT "District" FROM table_6558 WHERE "First elected" = '1856' AND "Incumbent" = 'william kellogg'
SELECT "District" FROM "table_6558" WHERE "First elected" = '1856' AND "Incumbent" = 'william kellogg'