Section 38. Before issuing notes or securities increasing county indebtedness, the county commissioners shall invite proposals for the purchase thereof by advertisements in two or more newspapers published in said county, if any, and by advertisements in at least three daily newspapers published in Boston. They shall reserve the right to reject any and all bids. The bids shall be publicly opened and noted in their records. If no proposal is made or accepted they may award the whole or any part of the loan to any person. Notes authorized by section thirty-seven, notes or bonds issued to renew or refund indebtedness existing at the time of issue thereof, notes issued for a term of not more than two years in anticipation of a serial loan, notes or bonds in anticipation of reimbursement from cities, towns and others in connection with work temporarily financed by the county, including tuberculosis hospital maintenance notes under section eighty-five A of chapter one hundred and eleven shall be excepted from the requirement of this section as to advertising for bids and may be sold at public or private sale.