In these cases, hydrotherapy can improve the general condition, and sometimes, it is said, disperse concretions. It promotes lixiviation and increased change of substance, as shown by increase of urea, and renders uric acid soluble. It will not, however, produce the marvellous cures sometimes expected of it.

The dietetic use of hot water in gout has been recommended, one or two tumblerfuls of water at 120° being given in the early morning. This is said to regulate the bowels, to cause the disappearance of lithic acid and lithate sediments, and diminish the frequency of acute attacks (Weber). Cadet de Vaux (1825) carried this idea to an extravagant pitch, ordering 8 oz. of hot water (120° to 140° F.) every quarter-hour for twelve hours. Some patients bore this, but others suffered from vomiting, excitement, congestion of the brain, or fever.

The formation of gravel is caused, according to Scherer, not by excessive secretion of acid, but by the fermentation of the urine itself, yet the diminution of the secretion of acid must produce a favorable effect; and also the dilution of the urine renders it less irritating to the mucous membrane, and washes away from the membrane, mucus which would produce fermentation. Hence plain water-drinking is good in this condition (Braun), though preference is now commonly given to mineral waters.