user: Question: Which District has a First elected of 1856, and an Incumbent of William Kellogg?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['Illinois 1', 'Elihu B. Washburne', 'Republican', 1852.0, 'Re-elected']
SQL:

assistant: SELECT "District" FROM "Table" WHERE "First elected" = 1856.0 AND "Incumbent" = 'William Kellogg';