We have clarified the behavior of impurities in sodium chloride crystals using secondary ion mass spectrometry.
1) In the case of monopoly salts, calcium and magnesium decreased from the surface toward the inside of the crystals. Their amount was very low inside. On the other hand, potassium concentration at the surface and inside of the crystals was almost the same.
2) In the case of crystals prepared by settling down, the amount of calcium and magnesium in the crystals was very low. On the other hand, potassium was contained in the crystals, and its concentration in creased exponentially in proportion to the potassium concentration in the mother liquor.
3) Potassium entered the sodium chloride crystal lattice where sodium ions should be situated.
4) In the case of crystals composed of sodium chloride and potassium chloride, sodium entered the crystals easier than potassium.

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Disinfection mechanism of electrodialyis system using ion exchange membranes has been investigated. One hundred minion (10⁸) cens/cm³ of E. coli cells suspended in 0.1-0.6 M NaCl aqueous solution were passed through a desalting chamber at aflow rate of 3cm³/min at various current densities (0.27-1.63 A/dm²) in the visinity of the limiting current density (0.81A/dm²).
Intensities of electric field in the desalting chamber of each condition were calculated from measured values of electric potentials, and from the caluculated values relasionship between intensity of electric field and disinfection effbct were investigated.
In the both cases of changing current density and NaCl concentration, it was found that vaibility of cells percentage (%) decreased with an increase in the intensity of electric field. E. coli cells in suspension were found to be completely disinfected over the value of 2.30 V/cm in the electric field intensities. The result sug gest that disinfection effects of electrodialysis system were deeply concerned with intensities of the electric field.
Electric conductivity of a E. coli cell was caLiculated from measured electrolyte amount, weight and water content in the E. coli cells, and compared with that of solution in the desalting chamber using 0.1 M NaCl suspension at the current density of 1.35A/dm² where electric field strength was 2.30V/cm. From the experiment, it was cleared that electric conductivity(0.248S/cm)of the E. coli cell was about four time as large as that (0.0057S/cm) of NaCl solution in the desalting chamber.
Taking the results in to account'it was concluded that the disinfection mechanism of electrodialysis system is an electrochemical electric conduction effbct in the surface and inside of E. coli cells, over the condition of limiting current density (0.81A/dm²).

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