Lead oxide melt, specific conductivity

The proposed model of the structure of oxyfluoride melts corresponds with the conductivity results shown in Fig. 69. The specific conductivity of the melt drops abruptly and asymptotically approaches a constant value with the increase in tantalum oxide concentration. This can be regarded as an additional indication of the formation of oxyfluorotantale-associated polyanions, which leads to a decrease in the volume in which light ions, such as potassium and fluorine, can move. The formation of the polyanions can be presented as follows ... 

This is prepared on an enormous scale by the lead chamber and contact processes. In the former, S02 oxidation is catalyzed by oxides of nitrogen (by intermediate formation of nitrosylsulfuric acid, H0S020N0) in the latter, heterogeneous catalysts such as Pt are used for the oxidation. Pure H2S04 is a colorless liquid that is obtained from the commercial 98% acid by addition first of S03 or oleum and then titration with water until the correct specific conductance or melting point is achieved. 

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