PROCEEDINGS OP THE COTTESWOLD CLUB 121 



sulphate of lime so esteemed by brewers is also likely to 

 be found in waters obtained by sinking wells through the 

 Keuper Marl. In water derived from peaty springs and 

 boggy uplands, and from the rich alluvial soils of fenland, 

 we may expect to find much organic matter, peat gener- 

 ally giving the water a strong brown tint, and an unpleasant 

 flavour. Water from the lias rocks is almost invariably 

 hard, and no harder water is met with than that from the 

 drift sands upon the lias. Such sand is probably often 

 capable of charging water with a large amount of carbonic 

 acid gas. This gas being derived by decomposition of 

 organic material near the surface, and contained in the 

 interstices of the sand, charges the water as it passes, and 

 thus charged, it readily dissolves the particles of lime 

 carbonate that it touches. 



The Effects of Movement and Stagnation 

 UPON Water 



The quality of water is considerably affected by move- 

 ment as in streams and rivers. In the first place, after 

 flowing for a long distance, it is often brought into 

 contact with a succession of rocks, from the quahties of 

 each of which it takes a little. It also takes up, carries 

 and redeposits insoluble matters, and exercises a maximum 

 effect in the destruction of organic impurities. In this 

 process of destruction the oxygen of the air is a very 

 important factor, and movement aids the aeration of the 

 water to a very pronounced extent. When fresh organic 

 pollution is received into a running stream, the micro- 

 organisms stimulated bv the extra amount of food aff"orded, 

 increase in numbers, and under their influence the organic 

 matters recently received by the water are quickly broken 

 up and reduced to simple compounds, but the micro- 

 organisms are aerobic, i.e., they can only effect their 

 purpose by the aid of oxygen, and the oxygen by which 



