48 



larger consumers, or even liousehold softening plants may He 

 erected. In order to furnish the chemical data necessary for 

 such treatment the accompanying table has been prepared. 



The samples of water analyzed have been sent to the Water 

 Survey from the various towns by the water- works men, the 

 city officials, or by other citizens. The Water Survey has not 

 been able to collect the samples itself, and thus can not be ab- 

 solutely certain that the samples are authentic. The probabil- 

 ity is that most of them are all right. 



The analytical work reported has been done in the Laboratory 

 of the State Water Survey" at the University of Illinois during 

 the past fifteen years. There is a possibility that some of the 

 w^aters have changed in character, but most of the well supplies 

 are very stable. 



Ninety-seven of the 216 separate sources of supply within the 

 State have been examined. The analytical data which is heed- 

 ed to determine the method of w'ater softening is given. Most 

 all of the analyses are reported in full in a Bulletin of the 

 State Water Survey.* 



The mineral content given in the table shows hypothetical 

 combinations which have been calculated from the ionic con- 

 tent by calculating bases in the order, potassium, sodium, am- 

 monium, n^agnesium, calcium, iron and aluminum, to the acid 

 ions in the order, nitrate, chloride, sulphate and carbonate. 

 By using this order the waters can be divided into several 

 classes. To facilitate comparison we made three classes. 



Class I. Includes those waters which contain more than 

 enough sodium to unite with all of the nitrate, chloride and sul- 

 phate ions. These waters would, therefore, contain sodium car- 

 bonate, and ])ossibly the carbonates of magnesium, calcium and 

 iron. The waters of this class will form a sludge or soft scale when 

 used in boilers. They may have a high soap-consuming power 

 when used for laundry or in the lavatory. The hardness, which 

 would necessarily consist of the carbonates of calcium and mag- 

 nesium, will be almost entirely removed by boiling, or by treat- 



*University of Illinois Rullctin, State Water Survey Series, No. 5. 



