562 Prof. Woodhead, The results of 



we carae to treat the same water with ozoue we obtaiued a siniihir 

 taste. With neither of these substances, chlorine or ozone, was 

 this taste obtained in the filtered Paris water or in the unaltered 

 Cambridge water, so that we put the taste down to the action of 

 the chlorine or the ozone upon an excessive amount of organic 

 matter present. These substances, which appear to be related to 

 the amines, chloramines, etc. must be farther studied*. 



The next method of sterilisation suggested was the treatment 

 of the water with chlorine. In 1894 Dr Cartwright Wood and 

 If were much struck by the remarkable sterilising power of 

 Hermite's solution — electrolised sea water containing chlorine 

 and hypochlorous acid. We found that very minute quantities 

 of this solution rendered sterile clear sewage from which much of 

 the organic matter had been removed and that in larger quantities 

 it was a most powerful disinfectant even in the presence of con- 

 siderable quantities of organic matter. 



In 1897 I had to go into the question of the sterilisation of 

 the reservoirs and water mains at Maidstone during the great 

 typhoid epidemic^. Having in view Professor Delepine's experi- 

 ments on disinfection by means of "bleach" solution, I filled 

 the whole of the Maidstone mains from the gravitation reservoir 

 with a 1 — 300 solution of chloride of lime or bleaching powder. 

 From the complaints received by the Water Company from all 

 sources I was satisfied that we had attained our object. 



In 1898 Kanthack, Robinson and Rideal§ carried out a series 

 of experiments on a similar substance known as " Electrozone " 

 by which "sewage tank effluent" or the filtrate from bacteria 

 beds was rendered almost germ-free. They found, however, that 

 the amount of organic matter was not diminished to any very 

 great extent by this treatment. 



In 1903 Lieutenant V. B. Nesfield, I.M.S.||, was so impressed 

 with the activity of chlorine in its sterilising power in relation to 

 sewage that he applied it to the sterilisation of water, using one 

 part of chlorine to 8,000 parts of water. This, of course, was 

 invariably sufficient to sterilise water, even that to which a con- 

 siderable quantity of organic matter containing the Bacillus coli 

 communis had been added. He used a tablet containing one and 

 a half grains of bleaching powder mixed thoroughly with half a 

 grain of sodium bicarbonate, this latter being added to keep the 



* It was found later that some of the taste was due to presence of oil blown over 

 the ozonizing area along with the air from the air pump. 



t Lancet, London, 1894, Vol. i, p. 1321. 



X Woodhead and Ware, Trans. Soc. Engineers, Session 1900 — 1901, London, 

 1901, p. 49. 



§ Sec Eideal, Selvage and Bacterial Purification of Sewage, London, 1900, 

 p. 151. 



II Public Health, July, 1903. 



