608 



SCIENCE. 



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



been mostly with metallic copper. I first 

 tried to obtain copper vessels for my ex- 

 periments, but finding that I should have 

 to wait some time to have these made, those 

 on the market being tin-lined, I decided to 

 use copper foil instead, which perhaps is 

 fortunate, as this is more convenient and 

 less expensive. 



In my earlier experiments I had a num- 

 ber of my students in bacteriology carry 

 on the work, using pieces of copper foil 

 about 25 centimeters square to each 2,000 

 c.c. of water, allowing this to stand from 

 four to eight hours at room temperature, 

 the copper foil being cleansed with pumice 

 for each operation. Agar plates were made 

 and it was found that there was a reduction 

 in the total number of organisms of from 

 85 to 97 per cent. For some time past one 

 of my special students has been carrying on 

 this work under my direction, and I may 

 say that in all of those experiments where 

 copper has been used the reduction in the 

 number of organisms has been equivalent 

 to what would be obtained by an efficient 

 filtration system, with the advantage in the 

 case of the copper treatment that the or- 

 ganisms are completely destroyed. 



In filtration processes it is generally 

 understood that both typhoid and colon 

 organisms are the first to be eliminated, and 

 without waiting to complete a systematic 

 study of the organisms which persist as 

 well as those which are killed in the copper 

 treatment of water, I thought it well to 

 test the method by using water containing 

 these organisms alone. 



Inasmuch as results depend in some 

 measure upon the method used, I will try 

 briefly to outline my method before giving 

 my results. 



1. Water under three different condi- 

 tions was employed: (a) Distilled water, 

 which was prepared from tap water by first 

 treating it with potassivmi permanganate 

 and then distilling it two or three times by 



means of apparatus constructed entirely of 

 glass. (6) Filtered tap water, prepared 

 by means of a Berkefeld filter attached to 

 a copper spigot, (c) Tap water collected 

 after being allowed to run through a copper 

 spigot for five minutes. All of these were 

 sterilized in an autoclave at 110 degrees for 

 thirty minutes. 



2. The cultures of typhoid and colon 

 which were used were pure cultures de- 

 veloped in bouillon for eighteen to twenty- 

 four hours. 



3. To 200 c.c. samples of water prepared 

 as above, and contained in sterile Erlen- 

 meyer flasks, were added two three-milli- 

 meter loops of the fresh bouillon cultures 

 of typhoid and colon bacilli, respectively. 

 Counting the duplicate experiments pro- 

 vided for, we thus had a series of twelve 

 flasks, six of them containing typhoid ba- 

 cilli, and six colon bacilli. 



4. For studying the number of organisms 

 1 c.c. of the respective solutions was trans- 

 ferred directly to a Petri dish by means of 

 a sterile 1 c.c. pipette, and to this was 

 added 10 c.c. of Heyden's nutrient agar 

 which had been kept at a temperature of 

 40° C. for some time. Three separate plates 

 of the water in each of the twelve flasks 

 were made immediately upon the addition 

 of the cultures, and both the plates and the 

 flasks were kept at a temperature of 35°- 

 37° C. To six of the flasks were then added 

 strips of copper foil about 15 mm. wide 

 and 18 cm. long, these being corrugated in 

 such a manner that the entire surface was 

 exposed to the water. 



5. Plates were made from all the twelve 

 flasks at the end of four and eight hours, 

 and one, two and six days, even in the cases 

 where no organisms remained, and in the 

 cases where they continued to develop, at 

 the end of fourteen, twenty-one and twenty- 

 eight days. The results are given in the 

 following tables : 



