CAL′CULUS

Syn. Stone. In medicine , a hard concretion formed within the animal body by the deposition of matters which usually remain in solution. The concretions most commonly found are those formed in the kidneys or bladder, and termed urinary calculi, and those formed in the gall-bladder or biliary ducts, which are called biliary calculi. Urinary calculi are in most cases composed of substances which are constituents of healthy urine, such as uric acid, urate of ammonia, and the phosphates of lime and magnesia; they are, however, sometimes composed of substances which are met with in unhealthy urine, such as oxalate of lime, cystine, . Biliary calculi, or gall-stones, usually contain from 50 to 80 per cent. of cholesterin, a crystallisable fatty body, constituting a never failing ingredient in healthy bile, the rest of the concretion being made up of biliary resin and colouring matter, with a small quantity of inorganic salts. Calculus or stone in the bladder, which is a prevalent disease in Norfolk, both among men and sheep, has been attributed to the use of the hard water of the district. Both of these give rise to very painful symptoms, and may even threaten life. See Cholesterin .