Part V: The Nature of Birefringence

Abstract

The birefringence of Corriedale wool fibers was measured at nine different relative humidities. After being corrected for swelling the curve of birefringence against mois ture content showed a minimum at a moisture content of 19% of the dry weight of the wool. At this point the birefringence is probably completely intrinsic, but at other moisture contents there may be a component of environmental birefringence. The curve shape may also be due in part to change of intrinsic birefringence with change of moisture content. Environmental birefringence is not likely to constitute more than approximately 9% of the total birefringence at any moisture content.