SUBJECTS scale from hard water

The effect of an externally applied magnetic field on crystalline scale deposition, typically of CaCOs from hard water flowing in metal pipes, still remains a controversial subject despite the considerable number of investigations made over the past thirty years or so. There is still no general agreement on either the efficacy of commercially available devices or on the speculative mechanisms that have been proposed to explain their action (Sohnel and Mullin, 1988 Prasad et al., 1999 Kotsinaris et al., 1999). 

Four-connected nets with tetrahedral building blocks are of particular interest since they form the basis of zeolites and related materials. Zeolites are important in many areas, from large scale cracking of crude oils to the performance of washing powders in areas with hard water f I]. Thus, there is an abundant literature on the subject in contrary to the three-connected nets, and this chapter therefore will be briefer than it otherwise would have merited. 

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