April 21, 1905.] 



SCIENCE. 



611 



natural and more healthful, inasmuch as 

 the various inorganic constituents, particu- 

 larly the salts of calcium and magnesium, 

 are in a more soluble and assimilable con- 

 dition, being furthermore less concentrated, 

 at the same time the natural gases of the 

 water being retained. 



From the experiments thus far conducted 

 the following conclusions may be drawn : 



1. The intestinal bacteria, like colon and 

 typhoid, are completely destroyed by plac- 

 ing clear copper foil in the water contain- 

 ing them. 



2. The effects of colloidal copper and 

 copper sulphate in the purification of 

 drinking water are in a quantitative sense 

 much like filtration, only the organisms are 

 completely destroyed. 



3. Pending the introduction of the cop- 

 per treatment of water on a large scale the 

 householder may avail himself of a method 

 for the purification of drinking water by 

 the use of strips of copper foil about three 

 and a half inches square to each quart of 

 water, this being allowed to stand over- 

 night, or from six to eight hours, at the 

 ordinary temperature, and then drawn of? 

 or the copper removed. 



Dr. Mary E. Pennington, bacteriologist. 

 Department of Public Health, Philadel- 

 phia, said : In the city of Philadelphia, 

 work on an extensive sand filtration system 

 is being pushed just as rapidly as possible. 

 Portions of the city are now being supplied 

 with filtered water and in the course of a 

 few years such water will be distributed 

 over its entire area. Until this time ar- 

 rives there will, almost certainly, be out- 

 breaks of typhoid fever of greater or less 

 severity and extent. The problem of an 

 efifteient, wholesome and rapid purification 

 of water, primarily for the general city 

 supply, secondarily for use in the house- 

 hold, is, therefore, temporarily but em- 

 phatically, before the health authorities of 

 Philadelphia. Any method which offers a 



possibility of success must be carefully 

 weighed by them. 



Among the methods considered by the 

 city and worked upon in its laboratories is 

 that of the purification of water by copper, 

 either in the form of salts or as metal, the 

 aim being to eliminate typhoid and colon 

 bacilli. 



Dr. Stewart, working from the stand- 

 point of household purification more espe- 

 cially, has had constructed copper vessels 

 of varying sizes in which he has placed 

 typhoid germs suspended in distilled water, 

 sterile filtered water and raw river water. 

 In very clean, brightly polished copper ves- 

 sels the organisms of typhoid fever were 

 soon killed, sometimes in less than two 

 hours, and the common river water germs 

 were considerably reduced in number, but 

 never exterminated. In glass or tin, on the 

 contrary, all the organisms showed a de- 

 cided increase. 



The city laboratory has also conducted 

 some experiments to determine the germi- 

 cidal efficiency of copper plates charged 

 with very low electric currents — less than 

 4 volts and 0.01 ampere — over which the 

 water to be purified was allowed to flow. 



The siispension of copper electrodes in 

 water which is not agitated causes a more 

 rapid reduction in the number of organisms 

 than is accomplished by copper without the 

 current. When, however, the apparatus is 

 arranged to simulate a reservoir, with inlet 

 and outlet and of such construction that 

 the entering polluted water must come into 

 intimate contact with several electrified 

 copper surfaces, the reduction in the num- 

 ber of both typhoid and colon bacilli is 

 very great almost immediately. When such 

 an effluent has stood at room temperature 

 for an hour it is practically sterile. 



The copper, too, which, when germ-free 

 water is used, may be found in traces, is, 

 apparently, entirely eliminated from water 

 containing a large number of organisms. 



