If a silver-plating bath is exposed to strong sunlight, a small portion of the free cyanide will absorb carbonic dioxide from the air and part with its cyanogen, and thus become converted into potassium carbonate. The loss of free cyanide may easily be made up by adding a small portion of potassium cyanide dissolved in distilled water. When silver-plating baths are not in use, they should be closely covered to prevent this loss, and to keep out dust. They should also be well stirred an hour or two before being used again.