Apeil 8, 1910] 



SCIENCE 



557 



sewage and water, chlorine being especially 

 eflfective. 



The application of this method to swimming- 

 pool water was tried, with the result that hypo- 

 chlorite of lime in quantities sufficient to give 

 one part available chlorine to two million of 

 water gave efBcient sterilization. The pool when 

 so treated remained practically sterile for four 

 days, during constant use. No odor or taste from 

 the chemicals was noticeable. How often such 

 treatment need be applied must vary with local 

 conditions. 



Probably for the ordinary swimming pool, if 

 these experiments are borne out by experience, the 

 addition of hypochlorite of lime, in the propor- 

 tion of one part available chlorine to two million 

 of water, twice a week, would insure a practically 

 sterile pool. 



A New Device for the Isolation of B. coli: W. F. 



Weixs, Massachusetts Institute of Technology. 



A laboratory device was described which com- 

 bines certain advantages of both dextrose broth 

 and lactose bile. It consists of two Durham tubes 

 (the first containing an enrichment medium, as 

 dextrose, the second a selective medium, as bile) 

 so connected by a capillary that the production 

 of gas in No. 1 immediately causes a flow into 

 the bile tube. As the capillary leads from the 

 upper part of the inverted inner tube in No. 1, 

 further increase in gas lowers the liquid below 

 the mouth of the capillary and the flow cuts 

 itself off. 



If water containing B. coli is put into the dex- 

 trose tube the non-motile and aerobic bacteria 

 remain outside the smaller inner tube, while 

 B. coli, swimming continually in search of a better 

 medium, finds its way around; so it is likely that 

 such organisms will reach the portion about the 

 mouth of the capillary very soon. With every 

 advantage they multiply rapidly, and in a few 

 hours the inverted tube contains a seething cul- 

 ture of vigorous B. coli, and gas forms quickly. 

 The change in level causes a flow into the bile 

 tube, just at the time of most vigorous growth, 

 and then cuts itself off. The bile now contains an 

 almost definite measure of thriving B. coli, prob- 

 ably in pure culture. Under these definite condi- 

 tions the quantity of gas produced should be 

 regular, and the per cent, formed in a given time 

 after the first tube ferments significant. 



The tubes are handled almost as simply as 

 ordinary tubes. They are clamped together; a 

 small test tube is hooked into the short leg of 

 the capillary, while the longer legs straddle into 



both large tubes. They are made up and sterilized 

 as usual, filling upon cooling. 



The double medium secures the advantages of 

 both. It does more; it preserves B. coli at its 

 most favorable stage, the moment of gas produc- 

 tion, and inoculates the bile under definite con- 

 ditions with a dose of healthy organisms. It 

 may be reasonably expected that the gas formers 

 which are accustomed or can accustom themselves 

 to the digestive tract will be indicated. Practical 

 results show no unexpected error in the reasoning, 

 and as far as they go promise an efficient test. 

 NoEMAN MacLeod Haeeis, 



Secretary 



Univeesitt of Chicago 



SOCIETIES AND ACADEMIES 



THE PHILOSOPHICAL SOCIETY OF WASHINGTON 



The 677th meeting was held on February 26, 

 1910, Vice-president Abbot in the chair. The fol- 

 lowing paper was read: 



The Recovery and Discussion of the Earliest Mag- 

 netio Observations along the Antarctic Conti- 

 nent and in the Approaches to the South Mag- 

 netic Pole: Mr. G. W. Littlehales, of the 

 U. S. Hydrographic Office, Navy Department. 

 The results were chiefly in a chart of terrestrial 

 magnetic lines for the epoch 1840, representing the 

 inclination and the declination of the magnetic 

 needle founded upon the observations of the United 

 States exploring expedition which discovered and 

 traversed the coast of the Antarctic continent in 

 about 66° of south latitude between the 160th and 

 97th degree of longitude east of Greenwich, in the 

 beginning of the year 1840. 



The observations presented have but lately been 

 recovered from among a part of the records of the 

 exploring expedition of which all trace was lost 

 for many years, and they have resulted in the 

 portrayal of a passing state to which we could not 

 otherwise have reascended. 



Such magnetic lines from original observations 

 made long ago have a value which increases with 

 the lapse of years on account of their importance 

 in elucidating the changes which time works in 

 altering the magnetic state of the earth. 



The interpretation of the results proves that 

 American explorers were the first to point out the 

 region of the south magnetic pole by disclosing 

 its presence, at that epoch, as an area of consid- 

 erable extent, over which the dipping needle stood 

 vertical or nearly vertical, around a position in 

 68° 50' of south latitude and in longitude 135° 

 east of Greenwich. 



