The volumetric method of determination of bismuth as proposed by Malaprade is based upon the fact that bismuth hydroxide can be converted into the trithiosulfatobismuth complex by first adding a large ogcess of sodium thiosulfate and then adding carefully dilute nitric acid to dissolve the hydroxide with methyl rod as the indicator for control.The complex can be titrated with standard sodium or potassium hydroxide solution using phenolphthalein as an indicator.