Rheumatism and Gout differ considerably from other fevers, both in their nature, and in the remedies which they require. They are produced by special morbid poisons or agencies, which we are enabled to counteract by certain Catalytic medicines. There is in both of them an excess of free acid formed in the system. Remedies which are apparently opposed in nature have proved useful in these complaints. On the Restorative plan, alkalies are the remedies required; for they neutralize the acid. But in spite of this excess of acid, some of the free vegetable acids have been used with advantage, particularly in rheumatic cases. We shall have hereafter to consider how far this operation resembles the common refrigerant action of these remedies just now considered. (_Vide Antiarthritics._) Some obscurity rests upon the subject of the use of Citric acid in scurvy; but as it seems to partake rather of the nature of a Catalytic than of a Restorative action, I have placed Antiscorbutics in the second division. Now, though there are possibly some exceptions, yet in most cases Acids act as simple Restoratives; but Alkalies certainly operate as Catalytics in some disorders, and have thus to be included in both divisions of Hæmatic medicines. ORD. III. ALKALIES. (Potash, Soda, Ammonia, Lime, Magnesia;--their Carbonates, and neutral Acetates, Citrates, and Tartrates.) We have to consider the alkalies now as Restoratives--treating of those cases only in which they are used to restore a wanting material to the blood or fluids of the body. That they pass into the blood, is proved by their solubility, and their appearance in the secretions; and that they are natural to it we know, because they are all found in it. Wöhler has demonstrated the curious fact that the neutral salts of the alkalies with vegetable acids undergo oxidation in the blood, being transformed into carbonates. (I have just said that it seems likely that certain conditions of the system may determine this oxidation, even in the case of the free acids.) Thus it may be easily shown how the neutral (bibasic) tartrate of potash may, with the addition of ten atoms of oxygen, produce two equivalents of bicarbonate of potash, together with four of carbonic acid and four of water. 2 KO, C_{8}H_{4}O_{10} + 10 O=2 KO + 8 CO_{2} + 4 HO. ____________ =2(KO, 2 CO_{2}) + (4 CO_{2} + 4 HO.) Again, one equivalent of the neutral acetate of potash, with eight of Oxygen, will make one equivalent of the bicarbonate, two of free carbonic acid, and three of water. KO, C_{4}H_{3}O_{3} + 8 O=KO + 4 CO_{2} + 3 HO. ____________ =KO, 2 CO_{2} + (2 CO_{2} + 3 HO.)