CREATE TABLE table_10638 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

What date was Richmond the home team?
SELECT "Date" FROM table_10638 WHERE "Home team" = 'richmond'
SELECT "Date" FROM "table_10638" WHERE "Home team" = 'richmond'