April 21, 1905.] 



SCIENCE. 



607 



will remove germs from water, whereas 

 copper is the only means thus far known 

 which accomplishes the desired effect with 

 algae. 



It should be most clearly understood that 

 it was not supposed for a moment that the 

 copper method could be substituted for effi- 

 cient sand filtration or any other means 

 now in use which has been demonstrated 

 as doing the work thoroughly. It was be- 

 lieved, however, and practical tests since 

 made have proved it, that in cases where 

 no system of filtration existed, or where the 

 filter failed, owing to the storage basin be- 

 ing flooded by surface drainage, or because 

 of leakage or other cause, this method was 

 not efficient, that in copper sulphate we had 

 the only remedy for such emergency cases. 

 It should be borne in mind that nothing is 

 more delicate or requires more intelligent 

 and conscientious supervision than a filter 

 plant. Any one who has had an oppor- 

 tunity to visit many such plants through- 

 out the country and really knowing their 

 inside workings, as it were, can not help 

 being astonished at the low rate of efficiency 

 frequently maintained. Consequently, the 

 application of copper sulphate under such 

 circumstances for the purpose of reducing 

 tie bacteriological content has been used 

 successfully in enough cases to demonstrate 

 that it has a distinct place in water purifi- 

 cation. Whether it would be efficient and 

 proper to use copper continuously during a 

 considerable period aw^aiting the completion 

 of a filtration system, is a question to be 

 decided by the conditions governing the 

 case. There is no doubt in my own mind 

 that under certain circumstances such use 

 would be justified, and the results would 

 more than repay any outlay of money and 

 labor. 



Others will discuss more particularly the 

 effect of copper upon typhoid, etc., so it is 

 not necessary for me to refer in detail to 

 the work carried on by the department 



along this line. One other point regard- 

 ing the effect of copper when used upon a 

 practical scale is of interest, however. That 

 is, that the theoretical strength, or the 

 amount of copper used to destroy algae and 

 bacteria in the laboratory, is considerably 

 greater than the amount needed on a prac- 

 tical scale. This may be due to the fact 

 that the organisms used in laboratoVy tests 

 are of necessity more resistant than those 

 occurring under natural conditions ; at any 

 rate, results show that where it may require 

 one part in a million of copper to destroy 

 certain algae under experimental conditions, 

 it only takes one tenth or even less than this 

 amount to accomplish the same result in a 

 reservoir containing millions of gallons of 

 water. 



Dr. Henry Kraemer, Philadelphia Col- 

 lege of Pharmacy, said : The purification 

 of w^ater supplies containing pathogenic 

 organisms being a subject of such vital im- 

 portance, it seems to me that any method 

 proposed for this purpose should receive 

 careful consideration, not only at the hands 

 of water engineers, water companies, health 

 officials and physicians, but by all those 

 who are in a position to test the method, or 

 contribute information regarding it, or to 

 foster a sentiment in favor of it if found 

 to be efficient. It was in this spirit that I 

 undertook to test the method proposed by 

 Dr. Moore and Mr. Kellerman. 



On account of the false sentiment which 

 had been engendered in Philadelphia with 

 regard to the purification of water by 

 means of copper, and recognizing that the 

 city authorities would not be apt to apply 

 the method so long as there was this preju- 

 dice against it, I determined to consider 

 the method in relation to its application 

 for household purposes. 



It is, of course, manifestly impracticable 

 for the average householder to use copper 

 sulphate in the purification of drinking 

 water, and my experiments have, therefore, 



