[Petrographic study of human and animal kidney stones]

1. It is necessary for the detection of the nature of the formation of renal calculi for the purpose of a correct diagnosis and the prevention of relapses to study it according to a complex method for every concrete case. 2. The zonal structure of the calculi is conditioned by different mineral composition which proves their variable medium of formation; this must obligatorily be taken into consideration when the constituents of the drugs are selected. 3. It is useful to examine completely the central part of the calculus under the electron microscope according to the suspension method for the purpose of the detection of the crystallisation centres which may have existed as minute particles. 4. For the rapid establishment of the composition of the renal calculi a thermic analysis must be performed with the help of which during 30 minutes the mineral composition of the calculus as well as the gauging mass for thermominerals which form the renal calculi may preliminarily be estimated.