Applying the modified "Pregl-Dumas" method" for the determination. of nitrogen to the metallic nitrides, the author succeeded to make it as a accurate and more rapid one than the ordinary. As the nitrides of V, Cr, Si, Al etc. are not soluble in the ordinary acids, the lower values of contents are subsequently obtained by the "Distillation method"; and even by the " Vacuumfusion method, " there are some prejudices to the requirements not only of a complicated apparatus of high vacuum train, but a particular attentions in all durations. The author determined the nitrogen contents in Fe, Si, Al, Cr, Ni, Mn, Ti, V, Zr and their alloys of previously nitrided or not, and comparing these results to that of by the" Distillation method" the possibility of applying his method is certainly convinced. The nitrides of Fe, Mn, Ti and Zr gave the consistent results in both method, but the higher values are obtained by the author's method in the case of Si, Al, Ni, V, W and their alloys.