Determn. of chloride ions in a road surface esp. after salting - by measuring colour change of silver (di)chromate gel with starch and silica when this is spread on the surface

摘要

Method for the approx. determn. of the amt. of chloride ions present on a surface, esp. a road, comprises applying to a predetermined area of surface, a paste contg. a predetermined quantity of silver (di)chromate, starch and pyrogenic or pptd. SiO2, the proportions of the starch to SiO2 being 1-8. The resultant colour of the gel is compared with standards obtd. using the same compsn. at the same rate of useage per unit area, on surfaces with known Cl ion contents. Used to determine salt remaining after salting road surfaces to melt ice and snow. A clear, precise colour change of the paste takes place of reddish brown to yellow which is reproducible.