SPRINGS AND STREAMS 



properly used may be of great service. Our 

 forefathers, who had fewer doctors and hos- 

 pitals than we have, often went to such spots, 

 which are far more frequent than we, who do 

 not require them so much, are apt to think. 



There is, in truth, no such thing in Nature 

 as pure water; all water has other substances 

 in it, but usually these other substances are 

 present in such small quantity that we are not 

 aware of it. We do indeed know that some 

 water is pleasanter to wash in than other ; for 

 instance, water that comes off or through a 

 chalk hill is hard and difficult to wash in. Rain- 

 water is said to be 'soft/ and is often collected to 

 use for washing purposes, even where there is a 

 plentiful supply of other water. When water 

 passes slowly through soil, sand and rock, two 

 different things happen to it. In the first place 

 it is filtered ; that is to say, it leaves behind 

 most of the solid impurities it contains round the 

 tiny spaces in the material of which the ground 

 is made. In the second place it takes away 

 with it some of whatever substance it passes 

 through that can be dissolved in water, and 

 carries this away invisibly, so that we do not as 

 a rule find out that there is anything there. 

 However, when we examine carefully the inside 

 of our kettles, saucepans, and other vessels in 

 which water has been kept, and especially where 

 it has been boiled, we do find that something 

 has been left behind in them which must clearly 



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