162 THE AMERICAN NATURALIST. 
Cole! suggests an approximately quantitative method for deter- 
mining potassium in the constituents of igneous rocks. It is a blow- 
pipe method differing from Szabo’s in that the assay is fused in a 
bead of sodium carbonate. The advantages of fusing with sodium 
carbonate in place of the gypsum used in the Szabo method are : (1) 
The certainty of differentiating the potassium from the sodium flame ; 
(2) complete decomposition of the assay ; (3) security against loss 
of the assay ; (4) convenience. 
1 Geol. Mag., March, 1898, p. 103. 
