Mineral waters have a somewhat evanescent popularity; one is rapidly succeeded by another: one that was highly eulogised is now neglected, and those which are now in favour will be, in all probability, discarded in a few years. At the present time there are many, though not a few holding a very precarious position in public estimation. Glauber’s Salt Waters, as the name indicates, owe their medicinal properties to the presence of the sulphate of soda, chloride of sodium, and other salts. They are more nauseous than Epsom salts, and slightly more irritating; the first may depend upon the condition of the palate, the other on the weakness or obstinacy of the alimentary canal. These waters contain saline aperients which exercise no little influence on the change of tissue; a result which should make them find great favour with patients who wish to diminish their bulk without affecting their muscles. These waters contain the chloride of sodium, the presence of which is, in my opinion, of more benefit than all the other salts put together, and which, if absent, would deprive the waters of their efficacy, or at least effect such modifications as would render them practically of but little use. All these mineral waters come from brine-springs, and whether they are called chalybeate, carbonated, saline, or hepatic waters, whether they come from Spa or Tunbridge Wells, from Carlsbad or Ilkestone, from Püllna or Cheltenham, Buxton, Friedrichshall, Droitwich, or Wiesbaden, their common origin is rock-salt, and to that mineral alone their virtues are principally due; the iron, magnesia, lime, and the other salts which they collect on their upward course are merely accessories, and are more useful to the proprietors than to the credulous recipients. They are purged freely, they are dieted carefully, and the blood is purified, and the result is of course beneficial; they could do the same at home, but then a weak solution of salt and magnesia or iron looks very homely when put side by side with some Carlsbad[56] or Friedrichshall waters: there is a great deal in a name, and the more nauseous a compound is the greater are its medicinal virtues; so think some. In all fevers, whether epidemic, endemic, or sporadic, the blood is thicker than ordinary, by reason of an increase of the fibrine and a decrease of the chloride of sodium; because the fibrine, which always has a tendency to coagulate, is not kept in check by the solvent properties of the chloride of sodium; this alone accounts for their partiality for salt.