Abstract: Nephelometric measuring devices are described. The nephelometric measuring devices can be configured such that an amount of scattered light having different pathlengths impingent upon one or more scattered-light detectors from a beam propagating through a suspension can result in substantially equivalent sensitivity and in correlation between the scattered-light detectors' response and a turbidity value of the suspension. The response of the scattered-light detector(s) receiving scattered light at a nephelometric angle of 85-110° from a beam of light propagating through the suspension can be in accordance to an equation selected from a group of non-linear equations where: x/y=anxn+an?1xn?1+ . . . +a2x2+a1x+a0; where “n” is an integer greater than 0; “x” is equal to the turbidity value of the suspension; “y” is equal to the response of the scattered-light detector; and “an” are calibration coefficients.

Abstract: A calibration suspension unit has a container made of a flexible material that is filled with a calibration suspension for the calibration of a turbidity meter. There exists no air supernatant above the calibration suspension in the container. Further, a method for the manufacture of a calibration suspension unit is provided and its use for the calibration of a turbidity meter is described.

Abstract: The present invention relates to a method of displaying colours on an electronic visual display. The colours correspond to a principal colour and one or more auxiliary colours each of which is defined by colour co-ordinates within a colour space. When one or more of the colours is out of the gamut of the display, adjustments are made to the co-ordinates of each colour to allow adjusted colours to be displayed that preserve the colour differences between the principal colour and each of the one or more auxiliary colours.

Abstract: A device for determining the ion concentration of certain substances, or mixtures of substances, in swimming pool water by admixture of color forming chemical reagents comprising measuring containers and at least one reference container combined to form a row of containers which have a common side wall. An indicating screen with a plurality of fixed, differently tinted indicating windows associated with the individual containers and distributed over the height of the containers is arranged in front of the common side wall, and the indicating windows associated with the reference container or containers are provided with a standard coloration relating to that formed by the color forming reagents.