156 S. G. WALTON. 



portion, while all the chlorine, sodium, potassium, and the 

 remainder of the magnesium and sulphuric acid passed into 

 solution. 



As 64°/° of the S0 4 and all the calcium remained in the 

 insoluble portion and as sulphate of magnesium if present 

 would have been removed by this treatment with alcohol, 

 one is driven to the conclusion that the sulphuric acid in 

 the dried residue is present chiefly as calcium sulphate. 

 Again as all the chlorine was in solution, the remainder of 

 the calcium together with the magnesium in the insoluble 

 portion, must have been present as carbonates, with the 

 exception of a small amount present as phosphate. 



The most probable constitution of the dried residue is, 

 therefore, as follows : — 



Sodium chloride 



Sodium bromide 

 Potassium chloride ... 

 Potassium nitrate ... 

 Magnesium chloride... 

 Magnesium sulphate 



Magnesium carbonate 



Calcium sulphate 

 Calcium phosphate ... 

 Calcium carbonate ... 

 Ferrous carbonate ... 

 Zinc carbonate 



Manganous carbonate 



Alumina 



Silica 



Organic matter, combined water, etc. (by difference) 



7*8000 



In conclusion I would like to mention that a partial 

 analysis of Sydney water taken from the Crown Street 

 Reservoir, which was made no less than ten years ago, 

 gave a figure for total solids of 7*3 parts per 100,000, while 

 the chlorine was 3*15. These figures indicate that both 

 the total amount and composition of the residue of the 

 water is extremely constant. 



Parts per 



100,000 



... ... 



4*4674 





.. 



Trace 



. . . 



, . , 



0*1820 





•• 



0*0175 

 0*3108 



. . . 



. , 



0*2909 



, . . 



» . . 



0*6783 



. . . 



. . . 



0*5878 



. . . 



, , , 



0*0088 



. . . 





0*1994 



. . . 



. , 



0*1610 



. . . 



, . 



0*0614 



. . . 



. . 



0*0104 



. . . 



. , 



0*0162 



. . . 



, , 



0*0950 



differei 



ice 



) 0*7131 



