The magnetic susceptibiilties of tropolone methyl ether (Ia), 2-methoxy-7-bromo-tropone (o-bromo-tropolone methyl ether) (II) and α-thujaplicin methyl ether(III) have been measured by use of the Gouy balance described in the previous article.^ The experimental results (-χ_M×10^6) obtained for (Ia), (II) and (III) are 71, 88 and 105 respectively. The susceptibility of crystalline form of (Ia), i. e., (C_8H_8O_2)_2H_2O (Ib), has been also measured, the result being - 160 ×10^ per mole. It has been shown that the value of ΔK_M, which shows the diamagnetic anisotropy of the tropolone ring belonging to each compound, can be easily derived approximately from the experimental value by the application of the empirical additive rule. The remarkable diamagnetic decrements have been observed in the ΔK_M values, the amounts of which depend upon the kinds of the substituents, i. e., OCH_3, Br and isopropyl groups. The results have shown that the ΔK_M value of (II) is almost zero and that of (Ia) is half the value of tropolone itself
