The Snyder Mfg. Co., being a large user of coal, entered into separate contracts with several coal companies. In each contract it was agreed that the coal company would supply coal during the entire year in such amounts as the manufacturing company might desire to order, at a price of $41 per ton. In February the Snyder Company ordered one thousand tons of coal from Union Coal Company, one of the contracting parties. Union Coal Company delivered five hundred tons of the order and then notified Snyder Company that no more deliveries would be made and that it denied any obligation under the contract. In an action by Union Coal to collect $41 per ton for the five hundred tons of coal delivered, Snyder files a counterclaim, claiming damages of $1,500 for failure to deliver the additional five hundred tons of the order and damages of $4,000 for breach of agreement to deliver coal during the balance of the year. What contract, if any, exists between Snyder and Union?