1. Effects. Hitherto I have been treating of alkaline substance-merely as antacids. When themselves in excess, they become real dynamic agents, producing important modifications in the condition of the system. Strictly speaking, this subject should have been considered in the first division of remedies; and the proper place of the alkalies would, in this view, have been found among the arterial sedatives; but precision of classification may sometimes give way to expediency; and I have thought it would be both more convenient and more impressive to consider the alkalies, under these two different aspects of purely chemical and of dynamic agency, in the same place; especially as these two modes of operation are constantly running one into the other in practice.

When in excess in the stomach and bowels, the alkalies act as irritants, and, very largely given, or in a concentrated state, may cause severe inflammation, and even corrosion. Their abuse is apt to induce want of appetite, gastric uneasiness, and other symptoms of dyspepsia.

A certain excess of alkali in the blood is essential to the continued solubility of the albumen and fibrin, and possibly for other purposes; but, beyond the normal amount, it produces depressing effects, dependent probably on a direct alteration in the condition of the organized constituents of that fluid. The coagulability of the fibrin is probably impaired, and, under a very powerful influence, the blood-corpuscles themselves, to a certain extent, broken up and dissolved.

In the urine, a similar excess disposes to the deposition of the phosphate of lime, and the ammonio-magnesian phosphate, which require the presence of acid in the urine to hold them in solution. A tendency to calculous formations may thus be promoted.

2. Therapeutic Application

But, while excessive alkalinity in the system is thus in various ways injurious, a certain amount of it may be advantageously applied to therapeutic purposes. From the influence exerted on the blood, that fluid becomes less capable of duly supporting the vital processes, and a general depression is produced. Hence the alkalies may sometimes be advantageously employed in inflammatory and plethoric affections. They are supposed to be peculiarly efficacious in pseudomembranous inflammation, as they diminish the coagulability of fibrin, and therefore lessen the tendency to its exudation in the plastic state. On this account they have been used largely, and with supposed advantage, in pseudomembranous croup, and might be employed, with hope of benefit, in similar affections of the bronchial tubes and alimentary mucous membrane, forming varieties of bronchitis, enteritis, and dysentery. it is probable that they operate advantageously in acute rheumatism, much more on this antiphlogistic principle than by the mere neutralization of acid.

Cutaneous eruptions are among the affections in which the alkalies are most frequently used; being taken internally, and not unfrequently applied externally at the same time. internally, they act in part by neutralizing acid in the primae viae and the circulation, which has great influence in sustaining the eruptive affection, and in part probably as antiphlogistic remedies through their influence on the blood. Externally, they act mainly as local excitants; and may be employed among.

The earliest of this class of applications, as the disease is passing from the acute to the chronic stage, in urinary affections, the alkalies also act advantageously. As antacids, they have already been considered. But they are thought to be capable of doing something more than merely to neutralize the acid in the urine. it is believed that, by maintaining a constant alkalinity in the urine, uric acid or the urates deposited in the shape of sand or gravel in the uriniferous tubules, the calyces, or the pelvis of the kidney, may be dissolved; and the same possibility may even be considered as extending to stone in the bladder, composed of the same material. in the latter case, it has been proposed to effect a solution of the stone in the bladder by injecting solutions of the alkaline carbonates, or bicarbonates; but, though a rational proceeding, it has not hitherto been able to boast of much success, possibly from the want of sufficient perseverance.

It is highly probable that when the blood, under the influence of this class of medicines, becomes abnormally alkaline, the condition is corrected by elimination not through the kidneys only, but also through the liver; and that thus the bile may contain more than its ordinary proportion of alkali. Under this impression I have used this class of remedies, to a considerable extent, for the prevention and cure of biliary calculi, believing that the bile when thus highly alkaline might dissolve the calculi already formed, and, by holding cholesterin in solution, obviate further deposition. it has appeared to me that much advantage has accrued from the alkaline treatment in such cases.

The alkalies have been thought to possess a deobstruent power over chronic glandular and visceral enlargements; but their influence, in these affections, resolves itself into a simple antiphlogistic operation, through the changed state of the blood already referred to.

They have been recommended also in excessive obesity.

When alkalinity of the blood or urine is aimed at, it is on the whole best to use the bicarbonates, as less irritant to the stomach and bowels, than the more caustic preparations; and the neutral alkaline salts of the vegetable acids, as already stated, may perhaps frequently be substituted with advantage, as their acid undergoes decomposition, and the base enters the circulation in part as a carbonate.