Mat 24, 1907] 



SCIENCE 



809 



chemical sterilization of the rapid filter 

 effluents has been proposed. Experiments 

 carried out by the writer at the Sewage 

 Experiment Station of the Massachusetts 

 Institute of Technology seem to indicate 

 that the process is much more feasible than 

 has hitherto been supposed, and that it can, 

 in fact, compete with supplementary sand 

 filtration, as a finishing process for the re- 

 moval of bacteria from effluents. The most 

 suitable disinfectant thus far tried is 

 chloride of lime or bleaching powder. 



During the past summer and fall the 

 effluent of a trickling filter, treating Boston 

 sewage at a rate of two million gallons per 

 acre per day, was treated with bleaching 

 powder at a rate of five parts of available 

 chlorine per million of effluent. The aver- 

 age removal of total bacteria was 99.96 per 

 cent, and of organisms fermenting lactose 

 in bile media 99.993 per cent. The cost of 

 treatment for chemicals alone is $1.08 per 

 million. The time of contact was two 

 hours. Some special experiments in bottles 

 upon the germicidal action of bleaching 

 powder on B. typhosus showed a practical 

 elimination of that organism in from two 

 to four hours, the same amount of available 

 chlorine being taken. 



Results with copper sulphate were not so 

 satisfactory. During October the applica- 

 tion of one part of copper per million gave 

 a reduction of 94 per cent, of the total 

 organisms and 98.5 per cent, of the fer- 

 menting forms. The mean temperature 

 was 56°. 



In November, with a mean temperature 

 of 46°, the removal was 79.5 per cent, and 

 98.4 per cent., respectively. 



It was necessary to double the strength 

 of copper, two parts per million, to restore 

 its germicidal value to the first figure, when, 

 in December, the mean temperature was 

 43°. Under these conditions the efficiency 

 was, for the total organisms, 97.9 per cent. 



and for the fermenting forms, 98.8 per 

 cent. 



The cost of two parts per million of 

 copper as sulphate is about the same as of 

 five parts per million of chlorine as bleach- 

 ing powder. The germicidal effect of the 

 former is not nearly so great. 



Some experiments, previously reported 

 by the writer, showed that the presence of 

 organic matter (sugar or peptone), seri- 

 ously interfered with the toxic action of 

 copper sulfate on the typhoid bacillus. 

 A Substitute for Potato as a Culture 



Medium: P. G. Heinemann, University 



of Chicago. 



Ten grams of agar are dissolved in 600 

 c.e. water. A solution of the following 

 salts dissolved in 200 c.c. water is then pre- 

 pared : 



Dipotassium hydrogen phosphate 2 gr. 



Disodium hydrogen phosphate 2 



Magnesium sulphate 2 



Calcium chloride 2 



Ammonium lactate 2 



Asparagin 5 



This solution, in which a fine precipitate 

 forms, is added to the hot agar solution, 10 

 grams peptone dissolved, and the whole 

 mixture filtered after the reaction, which is 

 about 5 per cent, acid, is brought to the 

 neutral point with phenol phthalein. 



To the hot filtered solution 30 grams of 

 starch, previously washed in water and 

 made perfectly homogeneous in a mortar, is 

 gradually added with constant stirring. 

 The mixture is then brought to near the 

 boiling point and finally weighed. The 

 total weight should be 1,000 grams. The 

 medium is tubed and sterilized in the auto- 

 clav for 5 minutes at 120°, and cooled in a 

 slanting position. 



The Enzymotic Properties of Diplococcus 

 Intracellularis : Simon Flexnee, from 

 the Rockefeller Institute for Medical 

 Research. 



