Abstract: A method and apparatus for analyzing a fluid containing light scattering components. The apparatus includes a laser adapted to direct abeam of light into the fluid such as a liquid containing particles, and at least two detectors to receive light scattered by the fluid, which received light is used to calculate a physical property of the fluid. A focusing lens may be used to focus the light beam to a focal waist in the fluid to enhance the degree of spatial coherence of the scattered light. The two detectors are aligned onto the focal waist and are adapted to send a signal to a data processor which correlates the signal received from said two detectors. The two detectors are spaced a substantially equal distance from the focal waist and are oriented at substantially the same angle with respect to the direction of propagation of the incident beam. The data processor is adapted to cross-correlate the signals received from the two detectors.

Abstract: An efficient, inexpensive, in-line process is provided for producing additive-impregnated corrugated board, such as those having excellent rigid-when-wet and rigid-when-humid strengths. The process comprises applying an additive, such as water- and moisture-resistant resin, flame retardant, fire proofing agent, fungicide, mold-inhibitor, insecticide, or the like, in the form of a collapsible foam of a dispersion or solution of the additive to the corrugated medium, and desirably the liners, at the time the corrugated board is being formed.