In? In what? In traveling or "in administrative details"?

Context:

On moving to Peing I had the chance to learn Mandarin in its pristine purity, and at the time when it was begining to be the Kuoyu or national language, which gave it additional prestige. But I was at once plunged into administrative details which were carried on largely in English and soon began to spend much of the time in or traveling to and from the States;