Water quality; Examination and determination of colour
Описание (англ.):
Specifies three methods: 1. a method by observing a water sample in a bottle. This gives only preliminary information, for use in field work; 2. a method for evaluation by visual means and may be applied to raw and potable water and also to industrial water of low colour. This method is subjective with respect to the operator; 3. a method of evaluation by means of optical apparatus and is applicable to raw and potable water and to industrial water of low colour.