From some morbid condition of the system, it happens that these insoluble constituents of the urine are secreted in absolute excess,--in a larger quantity than in health. Now the system labours to excrete them in solution, even when in excess; and often succeeds in doing so. But frequently this cannot be done, it being impossible for a sufficient quantity of the solvent material to be formed out of the blood. There is then a deposit in the urine. We have seen that when such matters are deposited because in relative excess, the only fit mode of treatment consists in the administration of an acid or an alkali, which shall neutralize the morbid reaction of the blood. Such a case is rare; but these cases of absolute excess are much more common. There are two ways in which we may treat them; we may adopt either curative or palliative remedies. We may aim at the cause of the disease, which is generally in the blood. An absolute excess of Lithates may be caused by dyspepsia, or by a gouty disorder. This is most surely controlled by a Catalytic medicine. (_Vide Antiarthritics._) An absolute excess of Phosphates may be caused by an organic derangement of the nervous centres, when it is very difficult to cure; or it may simply be due to great nervous excitement, hard study, or melancholia. Such cases should be distinguished from a mere alkaline condition of the urine, without absolute excess of Phosphates, and may often be cured by attention to the disturbed nervous functions. Such a curative course of treatment aims at the primary cause of the deposit; but when we are unsuccessful in our attempt to control this, or when the excess of solid matter is so great as to be positively dangerous, we are then driven to have recourse to palliative remedies. These are Solvents; medicines which pass into the blood, combine there with the peccant matters, pass out with them into the urinary secretion, and hold them there securely in solution. Such an agent may often be advantageously combined with the Catalytic remedy, which tends to cure the systemic disorder. It is a blood-medicine. Its action is so far permanent, that it effects its object definitely, dissolving and carrying away a certain portion of insoluble matter. But as it also passes out itself, it requires to be frequently repeated, because the deposit continues to be formed, and requires each time a fresh portion of solvent. It obviously acts on the Restorative principle. The deposit should be excreted in a dissolved state, but is not. The remedy therefore supplies a want.