Abstract: The alkali-free or alkali-poor glass body is provided with an adherent and anti-reflective coating on at least one of its sides. The coating contains P2O5 and porous SiO2, preferably in a weight ratio of SiO2 to P2O5 of 10:1 to 1:1. It has a rubbing resistance criterion according to DIN 58196, intensity of testing H50, of 2 or better. The method of providing the glass body with the coating includes dipping the glass body in a H3PO4- and SiO2-containing volatile solution, withdrawing the glass body at a speed of from 1 mm/s to 20 mm/s from the solution and tempering the glass body at a temperature of under Tg of the glass.

Abstract: The glass body used in a solar energy apparatus is provided with an adherent and anti-reflective coating on at least one of its sides. The coating contains phosphorous and porous SiO2 and preferably has a rubbing resistance criterion according to DIN 58196-5, intensity of testing H50, of 2 or better. The method of providing the glass body with the coating includes dipping the glass body in a H3PO4- and SiO2-containing volatile solution, withdrawing the glass body at a speed of from 1 mm/s to 20 mm/s from the solution and tempering the glass body at a temperature of under Tg of the glass. The solution for making the coating containing porous silica and phosphorous is also part of the invention. It preferably has a pH of from 1 to 2 and contains from 0.1 to 2 percent by weight of HNO3 or HCl, a lower alcohol with from one to five carbon atoms, from 0.1 to 3.5 percent by weight H3PO4 and from 0.5 to 7 percent by weight of an SiO2 sol.

Abstract: A method and apparatus for the detection of leaks in an interconnected pipeline system are disclosed. The method involves recording flow characteristics over a specific, short time period, e.g., one-half hour daily, at control stations distributed throughout the network. By arranging the control stations in this manner, subnetworks are defined and the existence of leaks therein determined in accordance with deviations in measurements which facilitate localization procedures for the leaks. The apparatus is a well for use at the control stations immovably fixed in the network and accessible from the outside.