No. 6. 



DEPARTMENT OF AGRICULTURE. 



207 



from nitrates by decomposiug organic matter. In either case ni- 

 trogen as nitrites in water is considered a serious indication by 

 sanitary chemists. 



The term total solids refers to the residue left by evaporation of a 

 given quantity of water. It includes both mineral and organic mat- 

 ter and varies greatly both in character and quantity, even in pure 

 waters, depending on the character of the rocks through which it has 

 passed. While a general standard of purity is used to some extent 

 by chemists^ it is generally acknowledged that a local standard 

 based upon a knowledge of the composition of many samples of water 

 in a given region is more satisfactory. By comparing the results 

 of his analysis with the local standard of purity the chemist forms 

 an opinion as to the sanitary condition of a given sample of water. 



In the following table is given the results of the analysis of a num- 

 ber of samples of water taken from shallow wells, springs and 

 streams within a radius of twelve miles of West Chester. From the 

 results of these analyses and from the location and surroundings of 

 these w^aters, I believe them to represent a fair standard of purity 

 for the region just named: 



Pure W^ater. 



Source. 



o 



o 



1 

 2 

 3 



4 

 5 

 6 

 7 

 8 

 9 



10 

 11 

 12 

 13 

 14 



Stream 



Stream, 



Spring, 



Stream, 



Well, 



Stream, 



Spring, 



Well. 



Well. 



Well. 



Stream 



Spring, 



Spring, 



Stream 



54.8 



60.00 



30.00 



127.00 

 64.00 

 77.00 

 77.00 

 77.00 

 70.00 

 64.00 

 80.00 



120.09 

 41.00 

 64.00 



Samples numbered 4 and 12 are exceptionally high in total solids. 

 This is due to the fact that these samples were taken from a lime- 

 stone region and are consequently hard waters. 



Judging from the results of these analyses I am led to fix the stand- 

 ard for this locality as follows: Chlorine 4 or less. Nitrogen as 

 nitrites or, nitrogen as nitrates below 4. Nitrogen as N H3, below .08. 

 Nitrogen by alkaline permanganate 0.1 or less. Total solids usually 



