Urinary calculi.

IJANTITATIVE CHEMICAL ANALYSES of urinary calculi have been done in these laboratories for some twenty years. During this time almost two thousand stones have been examined. In the early days of this period, the only quantitative method available was that of a complete analysis of the inorganic ions and organic compounds present, which was quite difficult and tedious. After the development of the “ashing” method, details of which are given in the preceding paper, the estimation of the approximate chemical composition of calculi became a simple routine procedure. This article gives the results of analyses of 1700 urinary calculi by this method. About sixty per cent of the stones came from the Section of Urology of the Hermann Hospital. The remainder were sent in by physicians and hospitals in Houston, and from an area within a radius of one hundred miles of this city.