660 SCIENCE PROGRESS 



apparent in the hot-water system than it is in the cold, especially when the 

 boiler is driven at a considerable pressure, as the corrosive action is intensified 

 by the higher temperature, and the resultant damage is increased in a pro- 

 portionate degree. It is important that all valves, taps, and fittings should 

 be of the best quality gun-metal which is procurable, and even then, in many 

 cases, the seatings are rapidly destroyed and become ineffective in a com- 

 paratively short space of time, necessitating re-seating, perhaps, every few 

 months. This may appear to be inconceivable to many who have not ex- 

 perienced the possibilities of this class of water, but those who are familiar 

 with its effects will recognise that it is not an abstract proposition by any 

 means. Common brass fittings are quite useless in a case like this. 



It will be seen that a very troublesome situation is created when the only 

 available supply is of such a nature as this, and suitable steps should be 

 taken to eliminate the solvent properties of the water. 



There are several safeguards which are commonly employed under these 

 circumstances, most of which consist in the use of materials which do not 

 deteriorate in so marked a degree as others. Iron pipes and fittings are of 

 little value, as they are quickly attacked and rendered useless, while the 

 provision of brass fittings will not surmount the difficulty for a similar reason. 

 Copper is less subject to corrosion than either iron or brass, and is often used 

 in better-class work. The acid, however, has the effect of dissolving a minute 

 portion of the metal, thus imparting a green tinge to the water after it has 

 passed through the circulating system. In this state it is dangerous and 

 unfit for human consumption. To obviate this difficulty the pipes are fre- 

 quently lined with tin, which is immune from the solvent action of the water, 

 and gives excellent results, but is is extremely costly, as all portions of the 

 system, including pipes, circulating cylinder, and tanks, etc., must be similarly 

 protected on the inside. Lead is obviously out of the question, especially for 

 hot water, both on account of the excessive expansion of the pipes, and the 

 risk which is incurred of lead poisoning when it is taken into the system. 



It has been found possible of late years to manufacture glass-lined pipes 

 and receptacles, and this is, perhaps, the ideal method of storing corrosive 

 liquids, but the obstacles which are experienced in bending the pipes, and in 

 making effective joints between the interiors of the various sections, seriously 

 handicap the efficiency of the work. Here, again, also, the question of ex- 

 pense is a vital factor when deciding as to which method is the most suitable 

 under given conditions, and it will probably be found that glass-lined materials 

 are too costly for any ordinary domestic work. 



Although it is practically impossible to guard against the unfortunate 

 consequences arising from these conditions, by any mechanical means which 

 are really worthy of serious consideration from the point of view of efficiency 

 and reasonable economy, it is, at the same time, quite essential that some 

 steps should be taken to reduce the unnecessary waste which inevitably 

 occurs if the situation is neglected, and to eliminate the danger to those 

 persons whose bodily health would necessarily suffer, in some degree, from 

 the continuous use of water possessing such injurious properties. 



Most country residences are provided with their own water-supply, 

 especially when they are situated at some little distance from the nearest 

 available town main, and this supply is almost invariably obtained from a 

 well sunk in the vicinity. The best site for the well is on the higher open 

 spaces of the estate, as a purer quality of water is usually obtainable, on 

 account of the improbability of contamination arising from the proximity 

 of cultivated land and of inhabited dwellings. This class of land is often 

 unfit for cultivation owing to its stony and unproductive nature, and may 

 be comparatively unencumbered with buildings of any kind. It is fre- 

 quently covered with a top layer of peaty loam, and is almost destitute of 

 vegetation beyond quantities of gorse and heather, which thrive under 



