Identical Formulas Demonstrated with Folding Pocket Rule E. A. WILLEUMIER Dickinson College, Carlisle, Pennsylmnio
In the same way, the standard rectangular formula A FOLDING pocket rule can be used to demonstrate that identical formulas are identical, which is sometimes for malonyl urea disguises the fact that barbituric acid by no means obvious. is tri-hydroxy-pyrimidin, which, however, is easily Thus, two different conventions are extensively em- recognized when its formula is written with a hmgonal ployed in writing the purine skeleton. The older, skeleton. rectangular six-membered ring fused to a pentagon The joints in a folding carpenter's rule readily permit makes it only too easy to overlook the fact that purine the construction of, e. g., the older purine outline. may also be written as a hexagonal pyrimidin ring fused When the rule is now gently massaged it is metamorto an imidazole ring. phosed into the newer hexagon-pentagon skeleton.
