Barnes, the owner and operator of Blackacre, decided to cease farming operations and liquidate his holdings. Barnes sold fifty head of yearling Merino sheep to Billing and then sold Blackacre to Clifton. He executed and delivered to Billing a bill of sale for the sheep and was paid for them. It was understood that Billing woudl send a truck for the sheep within a few days. At the same time, Barnes executed a warranty deed conveying Blackacre to Clifton. Clifton took possession of the farm and brought along one hundred head of his yearling Merino sheep and turned them into the pasture, not knowing the sheep Barnes sold Billing were still in the pasture. After the sheep were mixed, it was impossible to identify the fifty head belonging to Billing. Explain whether Billing will recover the fifty head of sheep from Clifton.