The commissioner shall sit annually on the second Tuesday in July at his office in Trenton, for the purpose of equalizing the assessments between the several counties. At that time a hearing shall be given to the county boards of taxation and representatives of the boards of freeholders for the purpose of determining the accuracy of the ratios and true valuations of property as shown in the state equalization table, and the commissioner shall confirm or revise such table in accordance with the facts. The hearing may be adjourned from time to time, but the equalization shall be completed by August twenty-fifth. At the first hearing any county may object to the ratio or valuation of any other county, but no increase in any valuation as shown in the table shall be made without giving a hearing, after five days’ notice to the board of freeholders of the county affected.