12 SMALL WATER SUPPLIES. 



houses the hot-water boilers and cylinders have to 

 be of copper instead of iron. This is the case with 

 the Dublin water supply, users of which never install 

 iron boilers or cylinders, and all supply piping which 

 would otherwise be of lead has to be of a special alloy 

 of lead and tin. 1 The water also is very destructive 

 to street mains. This property of water of acting on 

 lead and iron is generally attributed to small quanti- 

 ties of peat in it. Water holding CO 2 in solution, if 

 free from oxygen, soon acts as an acid and rapidly 

 attacks iron. The minute quantities of peaty matter 

 in water undergo after a time a slow fermentation, 

 which gives rise to an increased volume of CO 2 above 

 the normal and to nitric acid. The introduction 

 of soda into water of this sort has the effect of neutra- 

 lizing the acidity, also about 3 grains of lime per 

 gallon would have the same result. Crushed lime- 

 stone in filter beds will also be of service, while stone 

 filtration has been found to be of benefit provided it 

 was slow. Further information on the subject will 

 be found in a paper by Mr. Kaye- Parry, M.I.C.E., 

 read before the Institute of Civil Engineers in Ire- 

 land, Vol. XXXV, 1909. 



Having thus reviewed the properties of water, the 

 sources of supply may be looked into. 



The one which would appeal to the ordinary per- 

 son first would be rain water. Country houses 

 usually have a large roof surface. Smoke does not 

 generally exist in the atmosphere, hence in most 

 establishments of this kind we find rain-water butts. 

 They are useful where the supply is limited, but it is 



1 Sir Charles Cameron, analyst to the city of Dublin, recommends foi 

 use in that city alloy pipe composed of g6 parts of lead and 3^ of tin. 



