The kind of mineral matter is perhaps of more importance in this relation than its total quantity. If the mineral substances present have medicinal qualities, as, for instance, sulphate of soda or sulphate of magnesia, less quantities of total solids are tolerated. If, on the other hand, they are of very little physiological effect, as, for instance, carbonate of lime and the sulphate of lime, a larger quantity may be tolerated. When a water has a total mineral content, of all kinds, exceeding 1,200 parts per million, it may be regarded as ceasing to belong to the potable class and to pass over into the realm of mineral waters.