124 PROCEEDINGS OF THE COTTESWOLD CLUB 



the water again reach a maximum. At certain seasons of 

 the year stagnant water is hable to get particularly foul 

 on account of the extraordinary development of certain 

 members of the lower algae which literally swarm in the 

 water and give it a peculiar unpleasant odour and flavour. 

 For these reasons it is a decided disadvantage to keep 

 water intended for drinking purposes in store for many 

 weeks or months together. The accidental introduction 

 of the bacteria of disease into such a store of water might 

 lead to results altogether overshadowing any possible evils 

 resulting from the use of the purified water of a river 

 such as the Severn. 



The Chemical Analysis of Water 



The suitability or otherwise of a water for drinking has 

 for long been judged by chemical analysis alone, but the 

 connection of bacteria with the origin of diseases has led 

 to the necessity of bacterial examination of water as well 

 as of its analysis. It must not, however, be for a moment 

 supposed that the value of chemical analysis is in any way 

 lessened by the recent innovation ; on the contrary, the 

 examination of water for bacteria is but an adjunct mode, 

 and its main value at the present time is rather to deter- 

 mine the efficiency of the purification of water, rather 

 than as yielding more direct information upon the general 

 suitability of any water for potable use. In the analysis 

 of watei: it is usual to make the following estimations.: — 



(1) The total solid matter contained in the water, 

 obtained by evaporating a measured quantity to dry- 

 ness and weighing the residue. 



(2) The hardness, which is equivalent to the quantity 

 of salts of lime contained in the water, one grain 

 of carbonate of lime, or its equivalent in sulphate or 

 other salt of lime representing one degree of hard- 

 ness, the hardness of water being sometimes also 

 partly due to magnesia, Sec. 



