This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
In cases of colic and constipation dependent upon lead-poisoning, sulphate of magnesia is a valuable agent; it should be used in conjunction with iodide of potassium, and Dr. Lauder Brunton has well shown that if the latter remedy removes from the tissues the metal in soluble combination, yet it is readily reabsorbed unless the bowels be freely and regularly moved (Practitioner, vol. xii.): 1/2-oz. doses may be required. Dr. Copland and others used the sulphate with sulphuric acid before the special value of the iodide was known.