Dr. Jacob of Cudowa, in Silesia, has made a series of experiments on the power of stimulating the skin which is possessed by various kinds of baths. He has proved that mud and bran baths of the same consistence produce the same alterations in the circulation, which are to be regarded as the real expression of the amount of skin-stimulation. It has been ascertained also that mud baths retain the heat of the bather more effectually than simple water baths. A carbonic acid bath is said to have the greatest stimulating action on the skin; a saline bath the next greatest, and mud and pure water follow next. A carbonic acid bath is also said to have the greatest power of causing general stimulation and excitement. As to the cooling effect of these varieties of baths, Dr. Jacob has noted that a water bath of an hour’s duration, and of a temperature of 91·4°, lowers the bodily temperature of a healthy man about ·9°; the mud bath of same duration and temperature 1·5°; the salt bath 2°, and the carbonic acid bath about 2·6°. _Sulphur baths_ in former times enjoyed a very great reputation in the treatment of skin diseases, gout, rheumatism, and the effects of metallic poisons, especially lead and mercury. There is, however, probably nothing peculiarly beneficial in the sulphur, and the good effect of these baths is due more to the heat of the water than to anything else. Many of the sulphur springs may rightly be regarded as salt waters also, and they have a great power of skin-stimulation, a power which adds immensely to their therapeutic efficacy. The bather in sulphur water is constantly inhaling the vapour of sulphuretted hydrogen, and this fact may have not a little to do with the good effects of the water. A course of bathing at a sulphur spring is generally combined with the internal administration of the water, and it is consequently a very difficult problem to determine whether the internal or external administration of the water has the greater effect in producing the desired cure. Steel baths, or baths containing iron, have fallen almost entirely into disuse, and any effect which was formerly attributed to the chalybeate water is now with more probability ascribed to the water and its temperature. The change in this respect is scarcely greater than that which has taken place at Carlsbad, where purgative waters, formerly used chiefly for bathing, are now almost exclusively employed for drinking. The author of the ‘Bubbles from the Brunnens’ thus describes his feelings while taking a steel bath at Langen Schwalbach, some forty years ago:--