The dry, crude drug, is the unit of medicinal strength, or drug 'power. It is the starting point from whence to calculate the strength of every preparation, be it tincture, solution or trituration. In making triturations or solutions of chemical substances, the matter is very simple, the first potency being the 1/10 or 1/100 of the crude drug according to the decimal or centesimal scale. In the case of tinctures, the dry drug also is the unit of drug power, but as this is soluble in varying proportions in different plants, the drug-power of the tinctures varies accordingly.