“ In objecting to Paragraph 2 (b) for its want of support in the Board's findings, petitioner contends that the Illinois unemployment compensation fund is in substance an unemployment insurance fund built up wholly from tax contributions by employers; that the benefits received from the fund by the employees cannot under state law be reclaimed or refunded; and that the eligibility of these employees for future benefits from the fund has not been impaired because of the benefits already paid to them. ”