LIMITS ON DUST IN RICH CLUSTERS OF GALAXIES FROM THE COLOR OF BACKGROUND QUASARS

I measure the V-I color distribution of two samples of radio-selected quasars. Quasars from one sample are projected on the sky within 1 deg rees of a rich foreground Abell cluster of galaxies, while quasars fro m the other sample are more than 3 degrees from any such cluster. Ther e is no significant difference between the color distribution of the t wo samples. The 90% upper limit on the relative reddening between the two samples is E(B - V) = 0.05 mag. This result limits the allowed qua ntity of smoothly distributed dust in rich clusters and contradicts pr evious indications of the existence of such a component.