When the said land is sold and the Board of Land and Works receives from the purchaser the amount of the value of the said land the Board shall pay to the Commercial Bank a sum not exceeding Two hundred and fifty pounds being an amount advanced to the trustees and expended in improvements on the said land and shall then upon such terms and subject to such trusts as the Governor in Council may approve pay the balance to the said trustees upon trust for the purchase and improvement of a site in allotment six, parish of Mooroopna, for a race-course and other purposes of public recreation and for no other purpose whatsoever.