The hot, _dry_ atmosphere of the Turkish bath promotes rapid evaporation from the surface of the body, and it is well known that rapid evaporation from the surface is a cooling process. A person's finger may be frozen in one minute's time, by throwing upon it a constant, fine spray of rhigolene or sulphuric ether. The rapid evaporation of the light fluid congeals the liquids of the tissues and a film of ice is rapidly formed upon the part. In a less intense degree the same cooling process is carried on over the whole surface of a person, when in the hot room, or _sudatorium_, of the Turkish bath. The evaporation from the surface is so rapid that one can hardly appreciate the profuseness of the perspiration going on. The evaporation from the surface so rapidly carries off the heat from the body that one finds himself able, with little or no inconvenience, to remain in a room heated to from 180° to 200° or even 220° Fahr. As a hygienic measure to be regularly or occasionally employed by persons in fair health, the Turkish or hot dry-air bath is far superior to the Russian or vapor-bath. (1.) It produces more profuse perspiration, and is therefore more depurating, or cleansing, in its effects. (2.) It does not relax the system, but rather produces a tonic effect, and fewer precautions are, therefore, necessary to guard against taking cold after employing it. (3.) The Turkish bath can be better ventilated than the Russian. While the air is heated to a high temperature, it can be readily kept pure by constant changes. In the Turkish hot-rooms, or _sudatorium_, of the Invalids' Hotel and Surgical Institute, provision is made for bringing underneath the floors a current of fresh air from without. This column of fresh air is carried under the centre of each room where it escapes from the conductor, is warmed, and rises into the room, from which extraction of air is constantly going on through registers opening into tubes, communicating with large ventilated shafts which are kept hot, summer and winter, to insure a draught through them. In this manner, thorough ventilation of our Turkish hot-rooms is insured. The Turkish bath not only combines a most agreeable luxury with a decidedly invigorating and tonic influence, but also, by its stimulating power, induces proper glandular and cellular activity, producing a healthy condition. Sallowness, tan, and freckles, the result of local or general increase of the pigment granules of the skin, soon disappear under the stimulating influence and regular use of the Turkish bath, which causes rapid development of new and transparent cells. The colored granules are thus gradually replaced and the skin assumes a beautiful clearness and purity of appearance, which transcends immeasurably the unhealthy hue that follows the frequent employment of the various cosmetics.