THE mine analyst, or assayer, as he is usually called, is frequently asked to determine the composition of mineral waters for battery, boiler, leaching, or other purposes. The tabulation of his results is generally a matter of taste, and is arranged in accordance with the wishes of the management; but it is usual to supplement the list of bases or metals and acid radicals with a statement showing the computed probable composition of the various salts in solution. Although it is some ten years since the writer was employed as a mine assayer, the many advantages of volumetric work as compared with gravimetric methods recently tempted him to investigate the estimations of the metal Mg and the radical SO4 volumetrically in connection with the examination of boiler waters. In connection with these researches an extensive series of experiments indicated conclusively that the volumetric methods herein described, inter alia (two methods for Mg and one for SO4), give results with certainty and regularity to within 0.2 % Mg0 and SO4 respectively. It is proposed to describe herein the methods adopted by the writer for the complete determination of all salts usually met with in mineral waters which come under the notice of the mining engineer.