Some additivity relationships in magnetic susceptibility measurements

(1) The magnetic mass susceptibility of a number of salts of ammonium and potassium have been measured, and also, a certain number of salts of magnesium, zinc and cadmium. Systematic relationships suggested by earlier workers for the potassium and ammonium halides, sulphates,nitrate's etc, were confirmed both in the solid states and in solution. (2) The present values of molar susceptibility of thehalides of ammonium and potassium were measured in both the solid state and in solution. The susceptibilities of salts in solution were about 1% higher than for the solid state,except in the case of certain divalent salts and the nitrates as a group. (3) Measurements on double salts of magnesium and zinc with ammonium and potassium were made. Additivity relationships in these salts in the dissolved state were found to be valid. Slight deviations were found In the crystalline state. In comparing the molar susceptibility of the double salt with its molar volume it was found that in the case of double salts containing the ammonium ion, the experimental molar volume and molar susceptibility are both larger than the calculated, and so differ from the calculated in the same direction. The relationship with the molar volumes was more complex in the case of potassium double salts. There is a fair correlation between the magnitude of the deviation for the two properties. The deviation from additivity was found to be larger in the case of certain divalent elements. (4) A series of measurements on divalent salts in solution was made at different concentrations. Some simple salts and acids were measured. In some cases the susceptibility of the salts and acids were constant in solution and showed no variations, while others showed slight change; a fall in susceptibility of the salt with increasing concentration being observed. 5) The susceptibility of solutions of salts of certain divalent elements showed a marked variation with the concentration. These changes were explained in termsof the concept of hydration number. This may include, in addition to simple hydration of the cation, more complex ion formation or the formation of ion pairs. 6) Measurements on solutions of zinc halides with equivalent proportions of univalent electrolytes showed systematic relationships.