Summary The values of the initial rotation of beta 2-arabinose recorded in the literature (175- 192') are low; by crystallizing the pure pentose very slowly we find the value [CY]:+ 202" in water. This value agrees with that which we find for the arabinose component of Dale's beta Z-arabinose calcium chloride monohydrate. The alpha form of arabinose has never been crystallized, but its crystalline calcium chloride compound recently discovered by Austin ...
