In a previous paper, [Liang and Hsii: Jour. Chinese Chew. Soc. 17, 90 (1950)]，we reported on the optimum conditions for determinin;, molybdenum as barium molybdate. In the present investigation it is found that the barium molybdate method may be employed to determine as low as b mg of MoO₃ in 200 ml of solution. The minimum concentration of excessive precipitant may be set at 5×10^-4 M, below which complete precipitation can not be attained. The presence of any metal that forms a slightly soluble hydroxide in solutions with a plf value edual to or greater than 6 is objectionable. The method requires the absence of even small quantities of zinc, a,nd permits the presence of less than 0.01 M of magnesium.