April 21, 1905.] 



SCIENCE. 



617 



to one half grain of metallic copper per 

 pound. ' ' 



If it be proved that copper sulphate is a 

 preservative by reason of its germicidal 

 character, then it falls under the general 

 rule of preservative substances. 



In this ease the findings of the Interna- 

 tional Congress of Hygiene and Demog- 

 raphy which met at Brussels in September, 

 1903, would apply. The third resolution 

 adopted by that congress in the section of 

 alimentary hygiene is as follows: 'The em- 

 ployment of antiseptics should be prohib- 

 ited in the preservation of alimentary 

 substances. ' 



Rideal states in his recent Avork, entitled 

 'Disinfection and Preservation of Food,' 

 on page 156, that the soluble salts of copper 

 have a distinct poisonous action on bac- 

 teria. The coagulated albumen combines 

 with most of the organic acids present to 

 form non-putrescible salts. They absorb 

 sulphur, hydrogen, ammonia and compound 

 ammonias and, therefore, combine with 

 ptomaines. In fact, copper salts rank 

 next to mercury in power as antiseptics. 

 Kroncke proposed a method for purifying 

 water with copper salts in volume 36 of the 

 Journal fiir GasheleucJifnng, page 513. 

 He used cuprous chloride in connection 

 with ferrous sulphate, and, finally adding 

 a small quantity of lime, succeeded in en- 

 tirely removing any residual copper. In 

 1892 the French authorities decided to 

 adopt as their otficial disinfectant in com- 

 bating cholera sulphate of copper. 



These few illustrations are given out of 

 many hundreds w'hich might be cited to 

 show that in general the opinion of experts 

 regarding the presence of copper in food is 

 decidedly unfavorable. To state particu- 

 larly my attitude respecting the use of cop- 

 per in water, it appears that, in the first 

 place, only bad water needs treatment, just 

 as only bad milk needs to be pasteiirized 

 or sterilized. I think that it is the general 



opinion among physicians, hygienists and 

 physiological chemists that the pasteuriza- 

 tion or the sterilization of milk is distinctly 

 prejudicial to the digestive processes and 

 should only be practised where greater dan- 

 gers, namely, those arising from infected 

 milk, are to be feared. This principle, it 

 seems to me, applies also to water. There 

 is practically no such thing as pure water 

 available for consumption. Water is the 

 scavenger of nature and tends to dissolve 

 or carry away mechanically all kinds of 

 refuse matter. Every spring and stream 

 is only a sewer. Nature, however, provides 

 means for at least partial purification. 

 These means are found in the germs which 

 water contains. The activity of such germs 

 is beautifully shown in the processes which 

 take place in the septic tank. A polluted 

 stream, and every stream is more or less 

 polluted, is only a septic tank of a different 

 character, and the reservoirs which hold the 

 waters which supply our cities are also 

 septic tanks. To add to water in a reser- 

 voir or other container a chemical reagent 

 which paralyzes germ activity by coagu- 

 lating the protoplasm, or in other ways, 

 renders waters powerless for self-purifica- 

 tion. There is also another point to be 

 kept in view, namely, the possible relaxa- 

 tion in care in controlling the water sup- 

 plies by the use of a sterilizing agent. Just 

 as the milk dealer may fail to wash his cans 

 or keep his cows clean, if he uses formalde- 

 hyde, so the officials of a city in charge of 

 the water supply may fail to care for or 

 supervise the purification of the water 

 sources if a cheap and efficient sterilizing 

 agent can be employed. It appears, there- 

 fore, that in most cases a sufficiently pure 

 water supply can be secured without the aid 

 of a sterilizing agent. If, however, a ster- 

 ilizing agent is to be used, there are great 

 difficulties connected with its control and 

 the universal tendency in such cases is al- 

 w^ays to use it in excess. This has been 



