A merchant in estimating the value of the personal property held for sale in the course of his business shall take as the criterion the average value of such property, as provided in this section of the Revised Code, which he has had in his possession or under his control during the year ending on the day such property is listed for taxation, or the part of such year during which he was engaged in business. Such average shall be ascertained by taking the amount in value on hand, as nearly as possible, in each month of such year in which he has been engaged in business, adding together such amounts, and dividing the aggregate amount by the number of months that he has been in business during such year.
As used in this section a "merchant" is a person who owns or has in possession or subject to his control personal property within this state with authority to sell it, which has been purchased either in or out of this state, with a view to being sold at an advanced price or profit, or which has been consigned to him from a place out of this state for the purpose of being sold at a place within this state.