ISO 10349-6:1992

The method is based on weighing the test portion, dissolution in water, transfer of a 20 ml aliquot in a beaker, pipetting halide standard A or B into a second beaker, adding nitric acid solution plus silver nitrate solution to each beaker, dilution with water, transfer of the treated solutions into separate Nessler colour-comparison cylinders, and observing the turbidity of the two solutions.