That Colchicum tends in some way to neutralize in the blood the poison of Gout, and to a less degree that of Rheumatism also, is generally admitted, although various theories have been adopted to explain this action. (_Vide Chap. IV. Art. Colchicum._) In Oxaluria, the employment of Nitric acid as a remedy was first recommended by Dr. Prout. Dr. Golding Bird advised the substitution of Nitro-hydrochloric acid, which has proved to be a most valuable remedy, not only in this disorder, but also in some cases of lithic deposit. The Oxalate of Lime rarely occurs alone in the urine; there is generally along with it some Urate of Ammonia. The causes of the two deposits appear to be in some way connected. So also are the remedies similar. Dr. G. Bird has found Colchicum to be of signal service in cases of lithic deposit in the urine; and has proved the same medicine to be efficacious in Oxaluria. I will now attempt to show how the action of these medicines may admit, on certain grounds, of a chemical explanation. There are very few Catalytic actions in which such an explanation can be attempted, but a degree of plausibility appears to attach to the idea in this case, though it cannot of course be considered to be susceptible of more than a demonstration of probability. I have already said that in all the disorders now under consideration there are certain morbid constituents in the blood which have been recognised by chemical tests. In Diabetes there is an excess of grape-sugar formed in the blood, and excreted from it in the urine. In Rheumatism we have a painful joint affection, attended with a great development of acid in the system; and this acid, which we have many reasons for supposing to be lactic acid, is occasionally excreted by the skin. In Gout we meet with another Arthritic affection, in which there is urate of soda in the blood, and an excess of uric acid and urea in the urine. A simple excess of uric acid in this secretion constitutes Lithiasis. There is an obvious but ill-understood connexion between the last two disorders, and, indeed, between all those of which we are treating. In Oxaluria we have an abnormal formation of oxalic acid in the blood, which is excreted in combination with lime, for which base it has a great affinity. In oxalic urine there is generally an excess of urea, as I have found in many cases. Now it seems to me that all these disorders are capable of being explained by reference to the series of changes in the blood which are associated with the respiratory process. (_Vide Liebig's Anim. Chem._, part i. p. 133; _Dr. B. Jones' Anim. Chem._, pp. 20, 118.)