The reaction was carried out in a 100-ml distillation flask having a side neck holding a thermometer which reached to the bottom of the flask.; the side tube of the flask was wide and branched from a high point on the neck. The flask was charged with 28 g (0.2 mole) of 4,5-dimethyl-2-furoic acid (see p. 28), m.p. 156–157°, and was then closed with a stopper through which passed a glass rod intended for clearing the neck from sublimate of the acid. The side tube was conected to a condenser, to which was attached a long receiver adapter; this passed down into the lower part of the receiver, which was cooled with ice water.