surpasses all other methods for the quantitative estimation of minute quantities of arsenic. The amount of paper or fabric taken for analysis has varied somewhat with the character of the material; e. g., whether a plain color or figured. Usually 100 square centimeters (about 16 square inches), occasionally 200 square centimeters, have been taken. In the case of figured materials, it is important to secure all the colors in fair proportion. This can be effected by the use of patterns of different dimensions. WILLIAM B. HILLS. BOSTON, Jan. 28, 1892. |