326 SCIENCE PROGRESS 



mixing can be assured, the actual amount being determined by the bacterio- 

 logical requirement of the water and the amount of water flowing in the 

 system at the point where the solution is introduced. Once the amount to 

 be added has been determined the process can be carried out by unskilled 

 labour, together with periodical bacteriological examination. 



The cheapness and simplicity of the method recommends it to the econo- 

 mist, but there are still a few in this country who would fain throw doubt 

 on its efficiency, although war experience has undoubtedly reduced their 

 number. One wonders sometimes how far the opposition is fostered by those 

 who have a special interest in the costly installation and skilled supervision 

 of the older variety of plant. Moreover, chlorination relies solely on the 

 bacteriological examination of the purified water, i.e. the evidence of presence 

 of living organisms as the standard of efficiency, and this has aroused the 

 ire of certain chemists who have hitherto looked upon chemical evidence of 

 past impurities as being the best standard to go by. Also the conservatists 

 consider that in slow sand filtration we have a method which has stood the 

 test of time, and there is no justification for replacing by a method which has 

 not been so tested. To those who say that chlorinated water has necessarily 

 a disagreeable taste, it can only be said that they have not experienced 

 a properly chlorinated supply. 



War did much to further the progress of science, as did science the progress 

 of war, and in the chlorination of water we have an example of both. Two 

 instances need only be given, namely, the Mesopotamian and Egyptian 

 campaigns. Without a simple method of efficient purification of water it is 

 difficult to imagine how the advance on Bagdad or the crossing of the 

 Sinai Desert could have been carried out by such large bodies of men in 

 the time done. Compared with these, all previous campaigns were 

 miniatures. 



The writer was associated with the latter, of which a few illustrative details 

 will be given. 



Along the first part of the route followed across the Sinai Desert from 

 Egypt to Palestine is a chain of wells, and this was sufficient for the advance 

 guard, as it was for the small army of Napoleon, but it was quite insufficient 

 for the main British army. The eastern part of the Sinai Desert is practically 

 waterless, and it was on the other side of this waterless area that the Turks 

 had entrenched themselves and actually managed to hold up our advance 

 for over a year. It was therefore necessary to provide the army with water 

 from outside Sinai, and the only one possible was the fresh-water canal which 

 takes the water of the Nile to Ismailia, Port Said, and the other stations along 

 the Suez Canal. When it is considered that this canal leaves the Nile near 

 Cairo and flows through some 70 miles of the Delta, where it is exposed to 

 every conceivable pollution, and that in addition it is bilharzia- infected, it 

 will be seen that the problem of purifying the water for consumption by troops 

 was no light one. 



In the ordinary way, such a polluted source would never be considered 

 for a municipal supply in this country, but in Egypt there was no choice, nor 

 was it to be expected that the army would go to the expense of the installation 

 of a slow filtration plant, even if such a method had been feasible in the dust- 

 swept desert areas where the purification had to be carried out. Moreover, 

 at Kantara, which was the base of the advancing force, space had to be 

 economised, as in many parts the brackish ground water was very near the 

 surface. 



It was realised that it was of negligible importance what the results 

 were as regards albuminoid nitrogen if a water could be provided which 

 was bacteriologically safe. To attain this end, rapid filtration plants were 

 erected and arrangements made for chlorination. To give an idea of the 

 amount of purification required, it should be stated that the colony count 



