26 



Cincinnati Society of Natural History. 



The hardness is expressed in metric degrees, or the nunil)er 

 of parts by height of Carbonate of Lime, or its ecjuivalent in loo.- 

 ooo parts by weight of water. 



Metric degrees muUipUed by o. 7;=:(irains in an Imp. (ial. 

 " " " 0.583= " a U. S. " 



Since potable water is also used in industries in which Iron is 

 injurious, in those series in which Iron Salts are the precipitants, 

 this element was determined in the clarified water. 



The amount of Iron was lound l)y color titration with Potassic 

 Sulphocyanide. 



Tabulated Tests of Waier Clarified by Precipitaiion. 



Series i, Canal Water. At Sycamore Street, Nov. 29, 1884. 

 Precipitant, Perchloride of Iron Solution. Sp. Gravity 1.74. 

 I Drop=o.o3o G. 



Series 2. Hydrant Water. Deceml)er 18, 1884. 

 Precipitant, Subsulphate of Iron Solution. Sp. Gravity 

 1. 418. 



I Drop=.o53 G. 



