WATER 27 



with any increase of temperature, while a decrease of temperature 

 causes the stopper to become so firmly fixed that it cannot be 



loved without fracturing the neck. No jug or funnel should 

 U used in filling the bottle and care must be taken when the 

 water is run in that it does not flow over the hand. 



In taking a sample from a pump or tap, some of the water should 

 be allowed to run to waste before filling the bottle, unless the 

 object of the intended analysis is to test the action of the water on 

 the service pipes, as, for instance, for lead solvency, in which case 

 the water should be left standing in the pipes all night and the first 

 water drawn off in the morning taken for examination. 



When collecting a sample from a stream, lake, spring or well 

 direct, the stopper should be inserted and the whole bottle sunk 

 well under the water, the stopper removed and the bottle filled. 

 This prevents the inclusion of surface water. When taking a 

 sample from springs and shallow streams, it is often necessary to 

 excavate a cavity sufficiently deep to hold the bottle and the hand ; 

 then time must be allowed for settlement to occur before filling 

 the bottle. When a bacteriological examination has to be under- 

 taken, all risk of contamination should be carefully avoided. The 

 bottles must be sterile and should have a capacity of 250 to 500 

 c.c., though a litre may be required. 



The stoppers of bottles should be covered with wash-leather 

 or clean linen, and must be sealed. A label should be affixed giving 

 the source, date and time of sampling, and the name of the sampler. 

 Full details concerning the water should be sent with the sample. 

 These include a statement as to the kind of analysis required, i.e., 

 chemical or bacteriological, or both; the reasons for wishing an 

 analysis ; details as to the source of the supply, and any information 

 pertaining thereto that may be of value to the analyst. The 

 proximity of drains, cesspools, &c., if known, should be stated. 



When the sample has been taken it should be transmitted to the 

 chemist with as little delay as possible. 



Physical Examination of Water. This includes the general 

 appearance of the water, its colour and turbidity, odour, taste 

 and, of lesser importance, temperature. 



Colour. Take two glass tubes two feet in length having flat 

 bottoms; place them on a white sheet of paper in a good light and 

 into one pour the water to be tested and into the other the same 

 quantity of distilled water. Special tintometers are used by water 

 analysts by means of which can be recorded the finer shades of 

 colouration. The water is examined vertically. A two-foot 

 column of pure water has a " pale sky-blue tint." A yellowish 



