Geologists, who are again and again forced to deal with the most minute or fragmentary specimens, and who find it impossible to cultivate, during their surveys of the earth, the methods perfected by the mineralogist in his learned leisure, have fully recognized the importance of Prof. Szabó's tabulation of the flame-reactions of the felspars. Since the accuracy of the results obtainable depends largely upon the position of the mineral-particle in the flame, I venture to call attention to a form of support that has proved in practice as convenient and efficient as it is simple.