Suppression of urine is very different from retention: in the former, there is none to excrete; in the latter, its escape is impeded. In the chapter on stricture, the cause and manner of retention is explained, and the mode of relief laid down, whereby the invalid himself has a remedy at hand; but, in suppression, the resource is neither so ready nor so effectual. It is, therefore, much wiser to notice the first alteration, and to be prompt in seeking the nearest aid. Every practitioner is acquainted with such. Although such are not ever present, even in the most extensive practice, still they do occur; and much as this mode of frightening a patient may be condemned, knowing the frequently existing disinclination toward “laying up,” yet, if it only induce a fellow-mortal to take the tenth instead of the eleventh hour, one life may be saved, and the writer can well submit to the disapproval and contempt of the thoughtless and indifferent. THE GRAVEL. UNDER the head of this disease may be classed all those urinary affections, wherein a sandy deposite is observed, after the urine has stood some time. This sandy excretion varies in its composition, in the quantity voided, and in its continuance: and it is also often separated, for it is held generally in solution in the urine as it comes from the bladder, while in the bladder or in the kidneys; and hence we find gravel in the kidneys, in the bladder, and in the urine. Where it is precipitated, or formed in the kidneys or bladder, it is apt to accumulate, and constitute what is called “Stone” in those organs. As I have just observed, the composition of this gravel differs, and differs also at different times in the same individual, according to circumstances. Stones have been detected that, like the rolling snowball, gather up, as they increase in size, whatever comes in their way; and, accordingly, as the deposites are principally composed of concretions, termed, in chymical phraseology, “Lithates” and “Phosphates,” stones are frequently found to be formed, first of a layer of one covering, then of another, and so on.