312 On Spring and Hirer IFater, as 



jected from all domestic uses ; often, however, its presence is 

 only accidental, and owing to some casual admixture or infil- 

 tration. The use of quicklime, thrown in small quantities into 

 the wells, is often found to remove this disagreeable adjunct. 



When the flavour is acid and sharp, and owing to carbonic 

 acid, the water need not be rejected as impotable, for it is in 

 no way injurious to the health. Every other flavour, however, 

 indicates the presence of something noxious ; and it should 

 not be forgotten, that the total absence of all flavour is no cer- 

 tain guarantee of the excellence of water. 



Every kind of strange colour should exclude all such water 

 from being employed for domestic purposes, except in cases 

 of absolute necessity, and, in these instances, it should be 

 filtered through charcoal. Thick and muddy water, however, 

 often becomes of excellent quality after it has remained in 

 a state of repose, or has been filtered through a bed of sand 

 or gravel. 



As to temperature, Hippocrates says that the best water is 

 that " which is warm in winter and cold in summer." In fact, 

 nothing is more disagreeable and more hurtful during hot 

 weather, than the use of water whose temperature approaches 

 nearly to that of the atmosphere. It appears that, however 

 excellent it may otherwise be, it is disagreeable to the taste 

 and sickening ; and a draught of it is not followed by that 

 sensation of refreshment and comfort, nor with that renewal 

 of strength and activity, which follows drinking cold water. 

 This enervating influence of warm water enfeebles the sto- 

 mach ; and a great number of the diseases which are com- 

 mon during the summer may be attributed to it. Fresh and 

 cold water may be considered, therefore, during the hot 

 season, as one of the necessaries of health for the popula- 

 tion of temperate climates, who do not, as in India, use ac- 

 tive stimuli for the support of the digestive powers ; and, 

 in this respect, spring-water, as maintaining a more equal 

 temperature, is preferable to river-water, which is much more 

 readily affected by atmospheric influence. 



As to chemical composition, water is light when it contains 

 a suitable quantity of atmospheric air and carbonic acid ; it 

 is soft when it does not hold in solution a quantity of cal- 



