400 
REPORT OF CHEMICAL LABORATORY 
Significance 
of high 
ammonia and 
nitrites 
Iron and 
manganese 
present 
Growtii of 
ci'cnothrix 
Necessity for 
filtration 
The fluorescein 
test 
Modification 
of usual 
test 
From the high temperature alone it appears evident that the water is, at least in 
great part, not the snh-soil water of the district, and that it, at some time in its history, 
was lying at a considerable depth. The high proportion of ammonia and the presence of 
nitrites do not necessarily, therefore, point to recent contamination. The existence, 
however, of iron and of manganese, tlie sum of which in the first sample amounted to 
1-5 and in the second to 1-34 parts per million, is in itself sufficient to render the water 
unsnitahle as a town sujjply. When the first sample of the water was tested it was 
predicted that orenothrix^ would sooner or later develop in the pipes carrying it. This 
prediction was verified even sooner than was expected. At the end of a few weeks the 
iron pipes leading from the pump, and a thin iron plate over which the water passed, were 
found plentifully furred by the growth, its early appearance being probably due to the 
comparatively high temperature of the water. 
Cairo is, in part, supplied by a water similar to the above in several particulars ; 
notably so in containing iron and manganese, the sum of which averages about 1-12 parts 
per million. This water has caused great dissatisfaction in use and a Commission 
appointed to study the question recommended the removal of the iron and manganese bj' 
aeration or chemical addition, followed by filtration. A similar treatment would be 
necessary in the case of the Khartoum water. It may he mentioned, in passing, that the 
bacterioscopic examination carried out by Dr. Balfour disclosed the water to be markedly 
contaminated, typical excretal B. c.oli having been found in so small a quantity’ as 0.02 c.c. 
Purification of this water must therefore be carried out, in any case, before it may Ijo 
passed as potable. 
As regards the presence of iron and manganese it may be noted that these are probably 
to be expected in well waters of the deep or artesian class in Egypt and the 8udan. 
Besides the two cases just mentioned, iron (and probably manganese) is jJresent in marked 
amount in the flowing wells of the Kharga oasis.- 
The Detec'tiox of Well Poltaitiox nv the T"se of Fluokesoeix 
It was noted above that the water of the deep wells intended to supply Khartoum was 
found to be markedly contaminated. An attempt was made to determine the source of 
this contamination. An abandoned bore-hole containing inquire sub-soil water and open to 
a depth of about 22 metres, which was suspected to be the cause of the trouble, was treated 
with a large amount of fluorescein and caustic soda and the water from the deep wells 
tested from time to time for a week, pumping being continuous for that time. No trace of 
fluorescein could be found. The water was in all cases evaporated to very small bulk 
(aliout one two-hundredth of the original) for the test. It was found that the concentrated 
water was so highly coloured that a satisfactory observation could not readily be made. 
The test was therefore modified as follows. From one to two litres of the water were 
evaporated to small bulk, a few drops of strong caustic soda solution added, and the 
* f'rniofhrls', an atinatic plant which grows in water containing iron or manganese, causes an accumulation in 
the distributing pipes of a gelatinous, iron-bearing deposit, which seriously impedes and may even entirely stop 
'the flow of water. Water affected in this way, besides being unsightly from the presence of long rusty filaments 
dislodged from the pipes, is unsuitable for laundry use, as it causes the linen to become iron-stained and corroded. 
- Bcadnell, Flowing wells and sub-surface water in the Kharga Oasis," i ii'utiiutphicnl Miujazinc^ Decade V., 
Vol. V., Nos. 5‘i4-n2.fi, Fcluaiary-^Iarch, 19b.S. 
