“…The conventional chemical method of magnesium determination-i.e., precipitation as the phosphate-is very lengthy, particularly if the separation from calcium is carried out; therefore, it was desirable to develop a more rapid method for control purposes. The spectrographic method presented in this paper covers a fairly wide range of magnesia, 0.2 to 12% magnesium oxide and is much more rapid, 2.5 hours' elapsed time for one analysis compared with approximately 16 hours by the conventional chemical method.…”