The structure of the $K$ absorption limits of some chemical compounds was examined with the double x-ray spectrometer. This instrument has been previously described. The $K$ absorption limits of the elements Ag, Mo and Cu and the compounds ${\mathrm{Ag}}_{2}$S, ${\mathrm{Ag}}_{2}$O, also Mo${\mathrm{O}}_{3}$, Mo${\mathrm{S}}_{2}$ and ${\mathrm{Mo}}_{2}$${\mathrm{O}}_{3}$ were examined for increase in width or fine structure. The width for the pure element decreases with increasing atomic number. The general effect of the chemical action was to broaden the absorption limit, but there was little displacement. In one case, ${\mathrm{M}}_{2}$${\mathrm{O}}_{3}$, there was evidence of fine structure. The silver salts appeared to be considerably reduced by the x-rays.Effect of temperature on the K absorption limit.---Recent experiments of H. S. Read (Phys. Rev. 27, p. 373, April 1926, and 28, p. 898, Nov. 1926) indicate an increase of absorption due to temperature of the absorbing element. Also the results were interpreted as due to a shift in the absorption limit. This matter was examined with double spectrometer. A strip of Mo was heated to incandescence in vacuum. The position and form of the $K$ limit was compared to that for cold strip. They were identical. No effect of temperature was detectable. This method would probably detect one-tenth the displacement estimated by Read.