Abstract: Conventionally, the concentration of a polar component in an otherwise non-polar or negligibly polar material, e.g., water content in pourable coal, is ascertained by measuring the attenuation of electromagnetic waves transmitted through a layer-thin sample of the material, the waves having a frequency as near as possible to the maximum-dipole-relaxation-loss frequency f.sub.o, in order to maximize the power-loss effect of the transmitted waves, this being directly attributable to the polar component, and thereby serving to accentuate the effect of the polar component in the measurement signal.

Abstract: A bituminized roof sheet has particular dimensional stability and strength when containing a spun fleece of polyester filaments reinforced in a quite special manner as carrier. The roof sheet has the following properties:A. a tensile strength of from about 30 to 100 kp/5 cm,B. an elongation at break of from about 20 to 60 %,C. an elastic strain of from about 1 to 5 %,D. a tear propagating strength of from about 2 to 8 kp,E. a nail plucking resistance of from about 13 to 30 kp, andF. a flexural strength of more than 5000 cycles.