Experiments on the Filtering Properties of the Zeer 



BY 



Captain R. G. Archibald, M.B., E.A.M.C, attached E.A. 



Pathologist anil Assistant Bacteriologist 



Wellcome Tropical Kcsearch Laboratories, Kliartouni 





,t^^ 



TV.' "•^ 



"'^ 



'« -■ ~- 



The zeer is one of the most useful domestic utensils employed in Egypt and the Sudan. 

 In these two countries its use is practically universal, for not only is it serviceable as a 

 receptacle for holding water, but also as a filtering medium for removing any turbidity. 



Up till a short time ago, and 

 before Khartoum was provided 

 with a water-supply, it was used 

 by all classes to clear the 

 drinking-water taken from the 

 river, and, while these conditions 

 existed, a few rough experiments 

 were carried out to test its 

 filtering capacity. 



Several types of zeers are 

 manufactured by the natives, and 

 the connnonest or white variety 

 is composed of clay moulded into 

 a suitable shape and then baked 

 at a high temperature. If a 

 section of a zeer be made and 

 examined microscopically, it will 

 be seen to consist of a somewhat 

 coarse reticulum of clay con- 

 taining portions of quartz and 

 haematite (vide Fig. 102). 



In carrying out these 

 experiments with the zeer, the procedure adopted was to fill it with 10 litres of river 

 water and to estimate the number of colonies of organisms present. Samples of 

 varying amounts of water were taken and plated out on agar. Samples were then taken 

 from the filtrate, and the colony count per 1 c.c. estimated in a similar manner. 

 Experiment I. New unused zeer. 



Average colony count per 1 c.c. water in the zeer = 340. 

 Average colony count per 1 c.c. of immediate filtrate = 236. 



After the water had been in the zeer for 24 hours, the latter was emptied, and 

 a fine slimy deposit was found adherent to its inner surface. This deposit was not 

 disturbed. lu order to see whether this deposit acted at this stage in any way as a 

 vital layer, ten litres of water were poured into the zeer, and samples tested after 24 hours 

 with the following results : — 



Average colony count of water in zeer = 200 odd. 

 Average colony count of filtrate = 400 odd. 





Bdchanan 



Action of the 

 slimy deposit 



