A magneto-optical method for viscosimetric measurements

We present a magneto-optical method using Brown's relaxation in ferrofluids . This method permits one to make some viscosimetric measurements by puttin g a drop of miscible ferrofluid into a test liquid, glycerol or diethylene glycol (DEG). To test this method we have compared our results obtained for glycerol with those obtained from a more conventional method and we observ ed good agreement. After this validation, we were able to study the viscosi ty of DEG between -20 and +90 degrees C by using our magneto-optical method . The comparison of these results with those obtained in standard ways (in the temperature range from -10 to +20 degrees C) revealed very slight devia tions.