28 



REPOET OF CHEMKAL LABOKATOKY 



After 192 hours' continuous pumping, tho water was again tested. It was found to 

 be in practically the same condition. The fiocculent masses were examined under the 

 microscope and found to be Grenothrix poli/spora or closely allied species. Iron and 

 manganese were present as follows : — 



Parts per million 



Iron 

 Maumiuese 



1-12 



olu 



The pipes having been cleaned and scraped, another sample was taken on March 1. 

 The odour of the water at its exit had disappeared, but the I'esults of the chemical 

 examination were unaltered. 



During my absence on leave in July, 1908, samples from Wells Nos. 2 and 3 were 

 taken by Dr. Todd, Bacteriologist to the Public Health Department, Cairo. These 

 were examined bv Mr.Goodson with results as follows: — 



These showed still higher proportions of manganese than the samples examined before, 

 but the sum of the iron and manganese was much the same. 



Two long series of determinations of tlie manganese were also made during pumping 

 trials on Wells Nos. 3 and 6. These showed the manganese practically constant at 0-3, 

 and 0-55 parts per million, respectively. 



Two more complete analyses of Well No. 7 were also made by Mr. Goodsou, at 

 Dr. Todd's suggestion, and one of a small surface well, the depth of which was 18 metres 

 only. The results were as follows : — 



