30 Cincinnati Society of Natural History. 



Variation of Hydrant Watkr in Hardness. 



Dec. 1 8. Rain after very dry weather. , . 11.5 Degrees. 



'' 28. River at flood — over 45 ft 9.9 " 



Jan. 24. River purified by freezing and 



snow 9.3 " 



Maximum variation 2.2 " 



The Water of the Ohio River may vary in hardness up to 2.2 

 metric degrees. 



Precipitant. 



The available precipitants for the clarification of Potable 

 Water as determined by this investigation, are highly concentrated 

 solutions of the following compounds: 



I. Aluminic Chloride Al2Clg(not examined) 



Aluminic Sulphate Al23So^i8H20. 



Alum (Ammonia) (H4N)oAl24So4 24H20. 



Ferric Chloride FeaClg 



Ferric Sulphate FcgSSo^ 



Ferric Sub-sulphate. . . Fe^O sSo^ 



Aluminic Sulphate. (Series 9.) 



50 to 100 parts by weight of Aluminic Sulphate will clarify 

 1,000,000 parts by weight of hydrant water in about 48 hours with 

 an increase of hardness of from ^-^ to i metric degree. 



Alum (Ammonia). (Series 6.) 



100 to 150 parts by weight of Alum will clarify 1,000,000 parts 

 by weight of hydrant water in about 24 to 48 hours with an in- 

 crease in hardness of from i to 2 metric degrees. 



Note on Aluminic Precipitants. 



The Aluminic Solids set free when Aluminum Salts are used 

 to clarify water, are so light that the precipitant remains floating in 

 the water for a long time after treatment, and when settled slight 

 agitation muddies the water. 



These compounds must therefore be followed by filtration for 

 the successful clarification of circulating water. 



