32 



REPORT OF CHEMICAL LARORATORY 



Plumho-.iolvenci/. The solvent action of the water on lead was tested by means of 

 a section of new lead pipe, about 2 metres long and 1-3 centimetres bore. The water 

 of Well No. 7 only was taken for the test, but as the waters of these wells differ but 

 slightly in composition,, the results, I think, may safely be taken as representative of 

 tlie supply as a whole. 



The lead pipe having been fitted with a stop-cock, it was filled witli the w-ater which 

 was allowed to remain for twenty-four hours. It was then run off and tested, and the 

 Action on lead pipe refilled. The tests were carried out in this w-ay for a month. In the beginning, 

 the amount of lead was approximately 0-7 part per million. The amount dissolved 

 gradually diminished, but at the end of tlie month the proportion found was still 

 considerable, l)eing about 0-44 part per million. 



Suitability 

 for irrigation 

 purposes 



SoBAT EiVEE Water 



In 1908, an attempt was made to carry out an investigation of the composition of 

 the water of the Sobat River, and Mr. Walsh, then of the Sudan Irrigation Service, 

 kindly undertook to collect the samples for the purpose. It was intended to make a 

 series of monthly examinations for an entire year, but Mr. Walsh, by reason of the press 

 of other work, was unable to secure more than nine samples. These were nevertheless 

 well distributed throughout the year and the results probably represent fairly well the 

 usual composition of the water and its variations. 



The results of the examinations are stated in the table on the next page. As will be 

 seen by comparison with those from the Blue Nile and White Nile, which have already been 

 recorded,' the Sobat water contains, on the whole, lower proportions of dissolved solids 

 than do any of the branches of the Nile examined up to the present. The proportions 

 of sodium carbonate and potassium carbonate are very markedly lower than is found in 

 the other tributaries of the White Nile or in the White Nile itself, and the Sobat 

 water should therefore be superior to these for irrigation purposes. One may also 

 reasonably expect the soil of the district through which this river flows, and which may 

 be subjected to inundation by it from time to time, to be of better quality than that 

 flooded by the White Nile. 



' Third Report, Wellcome Tropical Research Laboratories, pp. 386 to 395 



