560 fairchild: mineral sulphide water 



sary. As soon as the sulphide is precipitated the Uberated acid 

 immediately breaks up all the carbonate, or at least an uncertain 

 quantity of it. 



A series of synthetic waters was prepared, each being the ap- 

 proximate counterpart of the mineral water under examination. 



TABLE I 



Analysis of the Texas Mineral Water in P.\rts per 100,000 



This ratio of S to total COo is 1.4 to i.o. Tests were first 

 made on water containing only sodium hydrosulphide and 

 sodium carbonate. In preparing the sodium hydrosulphide, 100 

 cc. N/io NaOH was saturated cold with hydrogen sulphide, then 

 heated to boiling in a current of hydrogen sulphide and cooled. 

 A few cubic centimeters of this liquid remained neutral to phenol - 

 phthalein for a few seconds. This solution was then mixed with 

 one containing o.i gm. NaoCOs, and the whole was diluted to i 

 liter with water free from carbon dioxide. The percentage of 

 total sulphur, as determined iodometrically, was 0.369 gm. per 

 liter. This amount was confirmed gravimetrically by precipitat- 

 ing the sulphur as cadmium sulphide, which was in turn converted 

 to and weighed as cadmium sulphate. The result showed 0.388 

 gm. of sulphur per liter, or a somewhat higher figure for the 

 giavimetric method. However, the difference between the two 

 methods was only 5 per cent and could easily be accounted for 

 by slight impurities in the cadmium sulphate or by difference 

 in the samples taken. The sulphur content of the natural min- 

 eral water at the time of determining the alkalinity was found 

 to have changed to 0.156 gm. of sulphur per hter. The total 

 alkalinity as determined by N /20 HCl was equivalent to 0.600 



