MODERN ASPECTS OF WATER PURIFICATION 327 



usually exceeded 1,000 per c.c, indeed was often uncountable by ordinary 

 means, while bacillus coli was frequently present in 0*05 c.c. 



The success of the method will be seen by the results when it is stated 

 that throughout the campaign not a single epidemic occurred which could 

 in any way be attributed to this water supply, although conditions for the 

 spread of disease were most favourable. The supply from the purification 

 plant at Kantara, for example, was originally intended to supply 500,000 

 gallons a day for a small force of three divisions detailed to recapture the 

 Egyptian frontier towns of El Arish and Rafa, to which the water was pumped 

 in stages through a 12-inch main laid upon the desert sand. It proved so 

 successful, however, that when the conquest of Palestine was contemplated, 

 the pipe-line continued to follow the advancing troops and was subsequently 

 laid on to the Gaza-Beersheba line, a distance of 147 miles from the purification 

 plant and 220 from the Nile. 



A similar story could be told of the Mesopotamian campaign, in which the 

 water supply was for the most part drawn from the Tigris, sedimented and 

 chlorinated. 



At home, too, the Metropolitan Water Board, forced by the exigencies of 

 war which demanded economy of coal and labour, had set themselves a 

 similar problem. In the thirteenth Research Report, Sir A. C. Houston sums 

 up the position thus : — 



" Is it permissible to filter stored water so rapidly as to create an economic 

 gain in the saving of the filtration area, yet by the aid of anti-filtration or 

 post-filtration sterilisation processes to produce a water which is safe, 

 innocuous, tasteless, and reasonably satisfactory from a physical and senti- 

 mental standpoint ? " The subsequent reports on the London supply show 

 beyond doubt that the answer is in the affirmative, and that as regards economic 

 gain there has been a saving of thousands of pounds yearly since the adoption 

 of the chlorination method. 



The latter method is being extensively used in America, indeed bleaching 

 powder can be so cheaply made as a by-product at the great electric stations 

 that chlorine is also being used in the purification of sewage also. 



Thus has a method of water purification, which was chiefly elaborated 

 during the stress of war and which might otherwise have been largely neglected 

 for many years, been brought into prominence and shown itself to be one 

 capable of being of great benefit to civihsation in times of peace. 



Reference. — McDowaU : " The Water Supply of the Egyptian Expedi- 

 tionary Force," Journ. Hygiene, 1921. 



