Q. A ate at B's table for a period of two weeks and then entered into an agreement with him to board with him for the price of three marks per year. To bind the agreement A and B ate three pennies' worth together, as is the usual form of concluding agreements, which form is called einkauf. Subsequently A changed his mind and sought to invalidate the agreement. Some persons wanted to prove that einkauf was a valid form of concluding a contract from the talmudic law (B. M. 74a) under which the putting of a seal on wine barrels is a valid form of concluding a sale in those cities where it is customary so to conclude a sale of wine. A. Eating together as a form of concluding a bargain is a custom current among Gentiles but not among Jews. The agreement, therefore, was not valid and A may retract his offer. SOURCES: Pr. 730.