JAMA 100 Years Ago Section Editor: Jennifer Reiling, Assistant Editor.
We have referred several times to the claim made in some quarters in behalf of copper sulphate as a means of ridding water, not only of obnoxious algæ and infusoria, but of pathogenic bacteria as well. In so doing, we expressed hesitation about accepting, on the evidence then available, the doctrine that the addition of a few pounds of copper sulphate to a large body of polluted water was sufficient to free the water from dangerous germs. It now appears that this conservative attitude was fully warranted. A series of important investigations carried out on this subject under the auspices of the progressive State Board of Health of Massachusetts have just been published,1 and serve to shed a good deal of light on points heretofore obscure. It is shown that not only is the use of copper sulphate in water filtration not an aid to purification, but that, on the contrary, when the salt is applied directly to the water on the surface of a filter, it reduces the efficiency of the filter very materially, and eventually would seriously impair the essential biologic action of the filter. In accordance with the thorough-going methods of the Massachusetts Experiment Station, this statement is based on experiments lasting for a full year.
COPPER SULPHATE INSUFFICIENT FOR WATER PURIFICATION.. JAMA. 2006;295(7):836. doi:10.1001/jama.295.7.836-a