PROPERTIES OF WATER AND SOURCES OF SUPPLY. T t 



with a specially acute sense of smell. This usually 

 indicates the presence of FLS, which is not desirable. 

 It may, however, merely indicate stale or putrid 

 water. It is not proposed to go into the methods 

 whereby water is analysed. This is the business of 

 a specialist whose services under most circumstances 

 should be requisitioned by the engineer. The report 

 when received should state clearly 



(a) Total solids 



(b) Degree of total hardness 



(c) Organic carbon 



(d) Organic nitrogen 



in parts per million. 



(e) Ammonia 



(/) Nitrites and nitrates 



(g) Chlorine 



No determination is usually made of the quantity 

 of each constituent of saline matters either dissolved 

 or suspended, except in cases where lead or arsenic 

 may be suspected, nor is any notice usually taken of 

 dissolved gases. The term " previous animal or sew- 

 age contamination " may be observed in a report. Its 

 quantity is based on the ammonia and nitrates which 

 as stated are usually supposed to bespeak sewage 

 pollution. By this expression is represented the sup- 

 posed original contamination per 1,000,000 parts and 

 is reckoned up as follows. Let x = the ammonia and 

 y the nitrates, while is a constant employed, value 

 '320. Then the amount of contamination per million 

 parts is equal to 



A = 10 (x + y - z) . . . (i) 

 Mention has been made of the effect of some waters 

 on lead pipes which is very important, and waters of 

 this kind usually are so destructive on iron that in 



