The bonds and interest coupons attached thereto shall be delivered to the purchaser thereof only upon payment of par and accrued interest to the date of delivery thereof, together with any premium bid, if any. The proceeds of the sale of said bonds shall be deposited in the State Treasury of the State of Oklahoma, in a fund which is hereby created and designated the “1955 Building Bond Fund”, where they shall remain subject to disposition to be provided for by Legislature of Oklahoma, provided that the State Treasurer of the State of Oklahoma shall invest said monies in interest-bearing direct obligations of the United States of America, or of the State of Oklahoma, and provided further that, all such investments of said monies must be so made that the same may be liquidated in time to enable the State of Oklahoma to pay, in due course, the valid indebtedness incurred for the purpose for which said bonds are issued, when the said indebtedness has been incurred pursuant to legislative authority.