When a thin coat of nickel is deposited on iron and steel, the underlying metal gives its tint to the deposited nickel when polished. A similar bluish tint is observable in nickel deposited from an old solution contaminated with base metals. In such cases the colour of the deposit may be improved by adding to the solution common suit (sodium chloride) at the rate of 1 oz. of salt to each 6 gal. of solution at first: then note the results. If an improvement is observable, add more salt; but it is not advisable in any case to add more than 8oz. per 6 gal. If the deposit is still bad, the solution is unfit for use.