Abstract
The absorption band of formic acid vapor at 7825A has been investigated. This is a hybrid band in which the perpendicular‐type component is the more intense. The main features of the rotational structure have been measured, and by making reasonable assumptions the small moment of inertia is found to be 10.83×10—40 g cm2. The band is entirely similar in structure to the next lower harmonic band at 9801A.