Mr King on Recent Modes of Water Analysis. 33 



and indeed often does, occur in considerable quantity in water 

 wliicli is quite free from sewage, it must not by itself be taken 

 as an indication of iuipurity. Iron and lead are the constitu- 

 ents next mentioned. The former of these rarely, and the 

 latter never, occurs in natural water. They are both, however, 

 liable to be communicated to certain waters during passage or 

 storage in leaden or iron pipes and cisterns, and as they are 

 both, especially the former, objectionable ingredients in pot- 

 able waters, they should always in an analysis be carefully 

 searched for. We then come to the property known as 

 " hardness." The amount of this may to a certain extent be 

 inferred from the amount of saline matter present ; but as we 

 have a very ready and reliable method of determining its 

 amount, it should always be accurately ascertained. The 

 peculiar properties and disadvantages of a hard water are so 

 well known that I need not take up time enlarging upon the 

 subject, further than stating that these degTees of hardness 

 simply express grains of carbonate of lime. If we say, for 

 example, that a water has 10° hardness, we mean that it has 

 the same power of destropng soap as would be possessed by 

 a water containing ten gTains of carbonate of lime in the 

 gallon, or at all events lime and magnesia salts equal to that. 

 Of the next ingTedient, the colour, I require to say very little. 

 At the last meeting of the Society I read a note on my pro- 

 cess for determining the amount of this, which will be found 

 printed at length in the Proceedings (p. 26). 



Having thus considered, though somewhat imperfectly, I 

 am afraid, the different ingredients which I think should be 

 estimated in making an analysis of a potable water, it remains 

 for me to illustrate by a very few examples how I have found 

 this process to serve the purpose rec[uired of it. One of the 

 best examples I can give is one drawn from our own city. 



N'ot very long ago a sample of water was sent to me for 

 examination. It was, I may remark, stated to be Crawley 

 water obtained from an ordinary cistern ; it was all riglit to 

 look at, and if it had been analysed in the ordinary way it 

 would have showed little or none of the so-called organic 

 matter, and would therefore have been reported as pure. 

 By the mode of working which I have adopted, however, I 



