A COMPLETE ANALYSIS OF SYDNEY WATER. 149 



of ammonia given off on distillation, before and after the 

 addition of alkaline permanganate, being determined by 

 nesslerising the distillates. 



Nitrites— Ilosvay's napthylamine test was applied, but 

 no nitrites were found. 



Nitrates— One litre of the water was concentrated and 

 the nitrate estimated by reducing to ammonia by means 

 of sodium hydrate and aluminium foil, and after distilling 

 off the ammonia, nesslerising the distillate. 



Oxygen absorbed in 15 minutes and 4 hours— 250 cc. of 

 water were taken for each estimation. Dr. Tidy's modifi- 

 cation of Forchammer's method being followed with the 

 exception that the oxidation was carried out at room tem- 

 perature instead of at 80° F. 



Phosphates— As the phosphoric acid was present only in 

 traces, the method described by Dr. Oooksey in this Journal 

 Vol. xli, p. 171, in which standard tubes are prepared con- 

 taining known minute quantities of phosphoric acid, was 

 used. For the actual estimation, one litre of the water 

 was evaporated to dryness, and the phosphoric acid 

 estimated after the removal of silica by comparing the 

 ammonio-phospho-molybdate precipitates with those con- 

 tained in the standard tubes. 



Sulphates— Four litres of the water were concentrated 

 and the sulphuric acid precipitated and weighed as barium 

 sulphate. 



Temporary hardness— This was estimated by titrating 

 250 cc. of the water with N/50 sulphuric acid using methyl 

 orange as indicator. A blank experiment was carried out 

 with an equal quantity of distilled water, and the quantity 

 of acid required was deducted from the amount used in the 

 original titration. This method of estimating temporary 

 hardness may be used as the calcium and magnesium pre- 



