Potash and its salts have been used in Scurvy by Dr. Garrod, on the supposition that there is in that disorder a particular deficiency of Potash in the system. But the fact that Citric acid is at least of equal utility in the treatment of scorbutic diseases, would seem to be opposed to such an idea. When given in moderate doses, and not retained in the system, Potash and its salts pass out into the urine, and act as Diuretics. (_Vide_ pp. 126, 187, 193, 202, 206.) QUININE. Class I. Div. I. Ord. IV. TONICA. Though the utility of this important remedy is often of a sufficiently direct and obvious character, its precise mode of action is enveloped in no small degree of doubt and obscurity. This subject has been discussed at some length in the article on Tonics. It appears, from the character and results of its medicinal influence, that it is exerted primarily in the blood, and not on the nerves. It is included in the Restorative group of Hæmatics, and the general results of its action differ widely from those of a Catalytic Hæmatic. It produces no marked effect upon the system in health. Its operation consists in the cure of general debility, however produced, and in the prevention of periodic disorders in the blood. Debility depends on a want in the blood, and not on any active morbid process; and there are circumstances which render it likely that Ague may be curable by the supply of a similar want. Quinine is also serviceable in Gout, Scrofula, Dyspepsia, and other disorders; in all of which other medicines, which stimulate the secretion of the bile, are more or less applicable. Torpidity of the liver is likewise a usual accompaniment of the various forms of debility, and occurs in intermittent, remittent, typhoid, and yellow fevers; in each of which this medicine has been recommended, and used with advantage. In fact it may be said, that in all diseases in which Quinine is used there is a failure in the secretion of bile; and in all diseases in which there is a failure in the secretion of bile, Quinine is serviceable. There appears then to be some connexion between these two things. Certain of the constituents of the bile are formed by the liver out of the blood, for the purpose, apparently, of being again absorbed at some part of the surface of the intestinal canal. One of these, Taurine, has been shown to be chemically analogous to Quinine. Thus it seems to me to be not improbable that this alkaloid may be of service in these disorders by supplying the place in the blood of this biliary matter, which for some reason may be needful in the animal economy, or that it may actually become changed into the latter while in the system. Were this proved, its restorative action would be effectually cleared up. The Disulphate of Quinine (or Quina) is the preparation of the alkaloid which is most commonly used.