Of Natural baths, some are nitrous, some saline, some aluminous, some sulphureous, some bituminous, some copperish, some ferruginous, and some compounded of these. Of all the Natural waters the power is, upon the whole, desiccant and calefacient; and they are peculiarly fitted for those of a humid and cold habit. The nitrous and saltish are beneficial to the head, to defluxions of the chest, to a watery stomach, to dropsies, to swellings after diseases, and to collections of phlegm. The aluminous are fitted for spitting of blood, vomiting from the stomach, immoderate menstrual discharges of women, and repeated miscarriages. The sulphureous are soothing and warming to the nerves, and relieve lassitude, but weaken and upset the stomach. The bituminous occasion fulness of the head, and hurt the senses, but occasion a steady degree of heat, and soothe when persevered in. The copperish are peculiarly adapted for the mouth, tonsils, uvula, and eyes. The ferruginous are useful to the stomach and spleen. The descent into the water ought to be without precipitation, in order that its impression may sink deep into the body when in a relaxed state. * * * * * COMMENTARY. This Section is taken from Oribasius. (Synops. i, 29.) A fuller account is given in the Med. Collect. (x, 3 et seq.) See further, Aëtius (iii, 167); Haly Abbas (Theor. v, 13); Rhases (Contin. xxxvii); Avicenna (ii, 2, 15.) Hippocrates briefly mentions thermal springs of iron, copper, silver, gold, sulphur, alum, bitumen, and nitre. He speaks unfavorably of all such waters, as being hard and heating. (De Aër, &c. 35.) The ancient nitre or natron, it is now well known, was a native carbonate of soda. The alum, mentioned by Hippocrates and the other writers on the thermal springs, cannot have been the alum of modern commerce, since it is very rarely to be detected in mineral waters, but it must have been the alumen plumosum, or hair alum, which Klaproth found to consist principally of the sulphate of magnesia and iron. By far the most interesting account which has been transmitted to us of the thermal springs of the ancients is that given by Pliny in the 31st book of his ‘Natural History.’ He more especially commends the medicinal waters near Baiæ, consisting of all the kinds mentioned by Hippocrates and our author, namely, sulphureous, bituminous, saline, &c. Some of them, he says, prove medicinal by their vapour. He speaks of their good effects in diseases of the nerves and joints, and mentions generally of them that they open the bowels. Pliny’s account of the virtues of medicinal springs in different parts of the world is curious, but mixed up and disfigured with his usual traits of credulity and love of the marvellous.