618 



SCIENCE. 



[N. S. Vol. XXI. No. 538. 



illustrated so thoroughly in the case of 

 antiseptics in foods that it needs no further 

 elaboration. If water for potable purposes 

 is sterilized with sulphate of copper the 

 actual quantity necessary could only be de- 

 termined by most careful observation at 

 each time the reagent is used. If too little 

 is used the object is not secured. If too 

 much, the excess remains in the Avater. 

 Copper is nearly related to those metallic 

 substances which produce cumulative ef- 

 fects in the system, such as arsenic, mer- 

 cury and lead. Careful physiological re- 

 searches have shown that minute quantities 

 of copper long ingested produce great dis- 

 turbances, especially in the liver. It should 

 be the object, then, of the health officer to 

 furnish water as pure as possible, and, if 

 sterilization is necessary, to have it accom- 

 plished by means which are not likely to 

 introduce harmful substances. There ap- 

 pear to be two unobjectionable processes 

 capable of being used, one the application 

 of heat and the other ozone. 



In fact, in view of the well-known prop- 

 erties of copper and its salts in relation to 

 electricity, the query may arise whether the 

 germicidal etfects which have been proved 

 to ensue from the introduction of metallic 

 copper into ordinary drinking water may 

 not possibly be related to the production of 

 ozone. Dr. Kraemer has conclusively shown 

 the germicidal properties of copper when 

 placed in ordinary water. These proper- 

 ties must arise either from a solution of 

 the copper itself or from the electrical ac- 

 tivity developed, including, possibly, the 

 production of ozone. If the germicidal 

 properties are due to the solution of the 

 copper, then there is always danger of 

 excessive copper going into solution, thus 

 rendering the use of .such water objection- 

 able. 



One point which has been brought out by 

 the papers read to-night is worthy of care- 

 ful consideration, namely, that copper sul- 



phate may be used in quantities sufficient 

 at least to kill algse without leaving any 

 excess of the copper in the water. If cop- 

 per salts can also be used in sufficient quan- 

 tities to kill pathogenic germs and the 

 residual excess of copper be entirely pre- 

 cipitated thereafter, the principal objec- 

 tion to the indiscriminate use of copper in 

 water would be removed. At any rate, it 

 seems to me that it would be preferable 

 during times of epidemic, especially, to 

 drink water with a little excess of copper, 

 rather than to drink water containing the 

 germs of typhoid fever. 



The question is one of great interest from 

 many points of view, and my particular 

 purpose in speaking to-night is to say a 

 word of caution against the use of chemical 

 germicides and antiseptics which may them- 

 selves be sources of contamination. 



Copper sulphate is known to be one of 

 the strongest disinfectants and was adopted 

 as long ago as 1892 as the official disin- 

 fectant against cholera by the French au- 

 thorities. Disinfectants have their uses, 

 as we all know, but they should, if possible, 

 be kept out of foods, especially in eases 

 where there is no danger of epidemics. 



Mr. M. 0. Leighton, hj^drographer. Di- 

 vision of Hydroeeonomics, U. S. Geological 

 Survey, said : The application of copper 

 sulphate to storage reservoirs for the pur- 

 pose of destroying algJE has been quite thor- 

 oughly investigated by several men of good 

 standing and it has received sincere endorse- 

 ment. I have not, however, until to-night, 

 heard any detailed statements concerning 

 actual experiments upon its bactericidal 

 properties. Until the investigation of Dr. 

 Moore was made public, I had always been 

 of the opinion that copper sulphate was an 

 excellent disinfectant when used in solu- 

 tions of a comparatively high concentration, 

 and in fact during a period in which I was 

 engaged in public health work I made ex- 

 tensive use of such solutions in drains. 



