[Analysis of urinary calculi. Study methods].

A comparative study of the composition of a hundred urinary gravel stones is carried out, made by chemical analysis and spectroscopy infra-red. This research has shown that the spectroscopic method is better than chemical analysis: the latter method is excessively sensitive, above all when considering magnesium, phosphates and uric acid. The marked chemical disclosure of these substances takes us to false conclusions regarding the composition of the gravel stone with percentages varying between 20 and 40% of the cases. On the other hand chemical analysis has not revealed the presence of oxalates in 24% of the gravel stones examined. The spectroscopic method has shown itself to be simpler and faster to execute (a part from being more sensitive and precise), and capable of furnishing precise information on the composition of gravel stones, even very small ones of a weight of 500 microgram.