150 Chemieal Examination of Waters. 



of earthy carbonates and chlorides, and about 1^ of organic 

 matter, with 5 - 8 of hardness. But this river seems to vary in 

 composition at different times more than rivers generally do, for 

 in former years I have found as much as 22 grains per gallon, 

 and as little as 8 grains. 



At Penrith we have the Nepean mixed with the waters of the 

 Warragamba, and the specimen drawn on llth March, 1869 (not 

 a very favourable sample, being almost opaque from diffused 

 clay), contained 10 grains of solid matter per gallon, in which 

 common salt amounted to about 4 grains, and the hardness 3'4. 

 Some years ago I found as little as 5 "8 grains of solid matter. 



In examining a water chemically with a view of determining 

 its suitability for a town supply, it is rarely necessary to go 

 through the tedicus operations required in a full analysis. Every 

 useful end will in almost all cases be served by a statement of 

 certain leading particulars. In the first place, the appearance of 

 the water should be noted, that is to say, its condition as to 

 colour and transparency, and whether a sediment falls on stand- 

 ing. The sediment should be examined under the microscope, to 

 ascertain if there be living organic germs or animalcules present, 

 as from the character of these, we may draw useful inferences 

 regarding the organic matter in the water- — whether it be of a 

 harmless inert nature, or highly azotised, and in a state of putre- 

 factive change. It may be here stated that in none of the waters 

 now under consideration did the organic matter appear to be of 

 the latter character. 



Next, the taste and smell of a water should be noted, although 

 here we must guard against hasty inferences from specimens kept 

 for some time in close vessels. A water containing organic mat- 

 ter and earthy sulphates may, in such a case, generate a little 

 sulphuretted hydrogen, causing a bad odour and taste which the 

 water originally did not possess ; and the temperature of a water 

 when tasted is of some consequence, for if this be over 70' there 

 may be some disagreeable impression on the sense of taste, which 

 at a lower temperature might be absent. For a town supply, a 

 water should have no taste or smell whatever ; and what is really 

 meant when a water is said to have a good taste is simply that it 

 has no taste at all. 



Irrespective of any possible injurious effects on health, it is of 

 great consequence that a water intended for domestic use should 

 be free from taste and smell, and be pleasant to the eye. It 

 should be colourless, bright and sparkling, and should deposit no 

 sediment on standing. A water may be wholesome in the absence 

 of these qualities, but people will be deterred from using it as a 



