Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_66168 ( "Rank:" real, "Premier:" text, "Party:" text, "Assumed Office:" text, "Left Office:" text, "TOTAL Time in Office:" text )

### Question ###
what is the rank when assumed office on 12 may 1857?

### Accurate SQL ###

SELECT SUM("Rank:") FROM table_66168 WHERE "Assumed Office:" = '12 may 1857'