A study was made cf the cost per pound of magnesium sulfate monohydrate produced by a "Krystal" crystallizer at recirculation rates from 20 to 40 gallons per minute and operating temperatures from 150 to 180 °F. From these tests, the optimum operating conditions within the range of these variables were derived. The problem was studied by operating the equipment at all sixteen combinations of these variables in unit steps of ten. The crystallizer was operated at each set of conditions, the product collected, and the cost per pound determined. The operating conditions were found to affect power and steam costs greatly, varying from 1.689 mills/lb at 50 gallons per minute and 170 °F to 0.737 mills/lb at 20 gallons per minute and 180 °F, representing a decrease. cf 0.952 mills per pound upon correct choice of operating temperature and recirculation rate. / Master of Science