Abstract: A subscriber line circuit which truly implements all of the BORSCHT functions and which does not rely on an external ringing generator to provide the ringing voltage when needed is disclosed. This implementation is achieved by recognizing that supervisory and ringing signals occur in some sort of sequence and, therefore, do not have to be generated simultaneously. Based on this recognition, we provide a circuit which truly implements all of the BORSCHT functions and includes a power section that generates each of the supervisory signals, e.g., -48 volts and -24 volts, and alerting signal, e.g., ringing signal, in turn and as required.

Abstract: An aqueous slurry of backfill material e.g. slimes, includes a settable material and an activator therefor, e.g. pulverized fuel ash and lime, and a lubricant e.g. clay and a plasticizer, e.g. a lignosulphonate so that the slurry can be pumped over long distances but will then set to develop high early strength.

Abstract: A hardener for a polysulphide sealant comprises an inorganic peroxide and according to the invention includes as a cure control agent a naphthenate e.g. copper naphthenate and/or a phenolic compound e.g. cresylic acid.