When the urinary passages are healthy, the secretion of mucus from them is very slight, and the presence of urine in the bladder or its passage along the urethra usually gives rise to no pain. Pain and scalding are sometimes caused by an abnormally acid urine, or by the presence of crystals of uric acid in it, even though the mucous membrane itself be healthy. In such cases the use of potash or lithia is indicated to restore the healthy character of the urine.

When the bladder itself is irritable or inflamed, the secretion of mucus is increased and there is constant desire to micturate. There are here two indications to be fulfilled: one is to lessen the irritability, and the other is to remove the inflammation. In lessening the irritability, belladonna seems to be especially useful, and to diminish the inflammation, astringents are employed.

In inflammation of the urethra the same indications exist, and here also cubebs, copaiba, and sandal-wood oil are employed. It is, however, easier to apply astringents locally to the urethra than to the bladder, and consequently astringent injections are more frequently used: these are usually solutions of alum, sulphate or acetate of zinc, and acetate of lead.

Finely-divided powders act also beneficially by keeping the inflamed walls of the urethra apart, and on this account a mixture of sulphate of zinc and acetate of lead, which gives a fine, white, insoluble precipitate of sulphate of lead, is more efficacious than either of the solutions employed alone. Kaolin or china clay, which is a completely inert powder, as well as bismuth and calomel, have also been used for a similar purpose. As it is found that the secretion in gonorrhoea frequently, if not always, contains microscopic organisms, the injection of antiseptics has been used : among these may be mentioned permanganate of potassium and zinc, boric acid, carbolic acid, sulpho-carbolates, sulphurous acid, as well as drugs having both an astringent and antiseptic action, like chloralum, perchloride and pernitrate of mercury, and chloride of zinc.

The beneficial effects of copaiba in inflammation of the bladder and urethra are probably due to its antiseptic action. It is excreted in considerable quantities by the kidneys and renders the urine antiseptic, so that its decomposition and the appearance of bacteria in it are greatly retarded or completely prevented. The whole urinary passages from the glomeruli of the kidney to the orifice of the urethra are thus washed out by antiseptic urine, which does not decompose, and which tends to destroy or remove any germs that may be present. Cubebs, terpenes,1 and naphthalin2 have probably a similar action.

1 Schmiedeberg, Arzneimittellehre, p. 121.

2 Rossbach, Berlin. klin. Wochenschr., 1884, No. 46, p. 279.