Vol. Ill, No. 3.] Well' waters from tJie Uadhranumt. 171 



Sidav A saline deposit occurred iu some of the samples, and tliree 

 waters from the spring- heads were strongly impregnated with, 

 hydrogen sulphide. The total solid residue vaiied fjom 304 

 to 415'5 parts per 100,000 ; the smaller amounts being found in 

 the water as it issued from the wells and the lai'ger quantity 

 being found in the running streams. . Eliminating the samplea 

 containing the sulphur gases, there is seen to be a close agreement 



in the composition of the three waters, the difference being due to 

 concentration owing to the evaporation of the water over the hot 

 beds of the streams. The analyses of the samples from the 

 main sti^eauis of the tliree sources revealed the following consti- 

 tuents : 



Total T- Mag- -r» l ^ at t Clilo- Salph. Nitr 



,. , Lime. P Potasli. Soda. Iron. . k Ki a -^ 



solids. nesiH. rine. Acid. Acia, 



Harith.., 415-5 96-8S 9'55 20-60 59-21 2-8 46*5 145-3 '10 

 Ferath... 383'S 94'96 9-72 18-92 54-39 2-0 30'!> 146-2 tr. 

 Sida ,.. 409'6 87-50 IMO 17-37 58-83 2'5 35-5 1511 -II 



Calculating from the average of the above analyses one 

 hundred parts of the saline residvie would probably contain th& 

 following salts : 



Sodium sulphate ... ... 32'7 



Calcium sulphate ... ... 13'5 



Potassium sulphate •.. ... 8'6 



Magnesium sulphate ... ... 7*5 



Calcium chloride ... ... 16'2 



Calcium carbonate ... ..* 15'6 



Iron phosphate 

 Nitrates 



■ ft 



•6 



trace 



Combined water, silicn, etc. ... 5"3 



100 '0 



I am unable to trace any previous analyses. of Arabian well- 

 waters to compare with the composition of these from the Hadh- 

 ramaut coast except that of the sacred well at Mecca (Greshoff i» 

 Joani. Chem. Soc.^ 1898, A. 11. 614). Here the solids vary from 

 316 to 359 parts for 100,000, and considerable quantities of nitric 

 acid and chlorine replace the sulphuric acid found in the Ghail 

 wells. In the Nubian Desert similar saline water with large 

 quantities of sulphates are found in wells sunk in the sand-gmvel 

 detritus {Quart. Jotim. GeoL 6V,, 1897, 53, 374). 



The amount of hydroger* sulphide determined in the three 

 samples taken from the wells was 8'4!6, 7*2 and 12*2 parts in 

 lOOjOOO. These are equal to the amounts found in sulphur 

 springs of Sandefjord, Norway, and of Sicily. 



The fertilising properties are probably due to the presence of 

 potash and lime salts, and the action of the sulphates in liberating 

 the alkaline constituents fi'on\ the soil. In this respect the com- 

 position of the waters differs widely from that of Indian well- 



