In the present thesis an account or the original investigations on several aspects of the dia-and paramagnetism has been given. In the introduction, the results obtained in the present investigations have been briefly discussed in the light of recent theoretical and experimental work on the subject.
1. During the course of these investigations, the want and accurate and at the same time quick method for the measurement or the diamagnetic susceptibility of solids and liquid was felt. Gouy's balance was found to be suitable for the purpose. It was modified by enclosing the usual tube inside another tube the inner tube, containing a paramagnetic substance permanently sealed in it, served also as a stopper to the outer tube, which contained the diamagnetic substance. Care was taken that the combined pull was always in the downward direction. This balance .has been fully described in details in chapter I
2. The Magnetic moments of Co++ and Ni++ ions, obtained by the study of pure organic salts, have been found to more or less lie between the two values calculated by the Boss-stoner and the Van vleck formulae, which goes to indicate that there is a partial quenching of the orbital moment. These small variation between the ionic moment values shown by different salts give some idea of the extent, to which the orbital moment is quenches. In the case of cupric copper, both simple and complex compounds have been studied. The complete agreement with the Boss-Stoner value shows the complete absence of any contribution due to the orbital moment. These results are presented in chapters II & III.
3. The method developed by Bhatnagar and his pupils on the assumption that diamagnetic values are completely additive, has been used to calculated the ionic susceptibility of rubidium as well as cuprous ion from the study of their inorganic salts, ions are yet available. The mean ionic susceptibilities and the ionic radii obtained in these two cases compare favourably with those of other workers. The results are given in Chapters IV and V. In the cases of rubidium salts, it has also been found out that temperature has practically no influence on the diamagnetism of the salts in either the dissolved or the solid state. In conformity with the Weidman additive law, the effect of concentration of the salt dissolved in water on the diamagnetic susceptibility has been found to be linear over the range of concentrations studied. The ionic susceptibility of the crystalline state.
4. The low values observed in the case of magnetic susceptibility of cuprous and cobaltous cyandies are more likely in the magnetic measurements or for want of purity of the of the compounds. Thiocyanates studies have susceptibility comparable with those of the other compounds.
5. In Chapter VI and VII are given the atomic susceptibilities constants for monovalent iodine, tetravalent silicon, pentavalent phosphorous , di- and tetravalent sulphur as obtained by using pascal‚€™s atomic susceptibility constants. These compare favourably with the theoretical values of Pauling, Salter and Angus.
6. In chapter VIII, the condition for successful working on the Bauer and Piecard‚€™s U-tube apparatus, in which complicate arise at higher temperatures due to change in the ‚€˜wetting‚€™ conditions, have been worked out. Neither classical nor quantum theories suggest that diamagnetism should be anything but indo-pendent of temperature. In a number of the common aromatic liquids that have been studied, it has been found that the diamagnetism of aromatic liquids is, in general, independent of temperature. The slight increase observed at higher temperature can be ascribed to the fact that the atmosphere above the menisci of the liquid assumed to the air in calculations must necessarily contain a large percentage of the vapour of the liquid. During the course of further investigations on aliphatic and aromatic iodides, the reverse phenomenon, namely a decrease in diamagnetic with the rise of temperature, has been observed . The anomalous behaviour of iodine in compounds of this type may be responsible for the decrease in diamagnetism at higher temperatures.
7. In Chapter IX, it has been shown that the vapors of when heated above 700oC, thereby establishing that the become ground paramagnet state of S2 as well as Se2 molecules is 3‚ˆ‘. On the other hand tellurium vapour remains diamagnetic upto 1100oC. For working with Te2 vapour still higher temperatures are need and the electri furnace employed in the present investigation were conducted, spectroscopical investigations had so far not been able to bring about a decision as to whether the ground states of Se2, Te2Seo etc are 1‚ˆ‘ or 3‚ˆ‘ . similar experiments with metallic thallium, given in chapter X, have shown that its vapour become paramagnetic; but at about 1000oC, it attacks the envelope and again becomes diamagnetic. The diamagnetism at room temperature is associated with the polyatomic solid state and the paramgnetism, with the monoatomic vapour.
8. In chapter XI, a set up for a modified form of Decker‚€™s balance with arrangements for working at different temperatures is described. Aromatic liquids, organic iodides and rubidium salts in the dissolved state have been investigated on this balance.
9. The author‚€™s Bhatangar, F.R.S, for his continued interest and encouragement in the course of the work, for helpful suggestions and criticism and for placing all facilities at my disposal for carrying out the experimental work in the department of chemistry, University, University chemical Laboratories, Lahore