56 



SCIENTIFIC NEWS. 



[May 2nd, if 



ing in a hard water ; very much more soda is required, 

 of course at considerable expense, and, after all, the work 

 is very ill done. Of this any one may convince himself by 

 the simple process of washing his hands in a very hard 

 water, such, for instance, as that of Castleton, in Derby- 

 shire, or Kirby Shore, in Westmoreland. He will find his 

 hands, however carefully wiped, retaining a gluey sticky 

 feeling. The soap used has been decomposed by the salts 

 of lime (or magnesia) present in the water, and an in- 

 soluble lime-soap has been formed, which adheres to the 

 skin, or to linen, etc., and imprisons the dirt instead of re- 

 moving it. Hence washing or bathing in such waters is 

 by no means a sanitary process ; the pores instead of being 

 opened are clogged up by the lime-soap formed. A recent 

 writer has even gone so far as to ascribe many forms of 

 skin disease to the use of hard waters. 



It is further found that hard water is unsuitable for boil- 

 ing vegetables ; they will not be nearly as tender as if they 

 had been boiled in soft water. 



The industrial applications of water do not at present 

 come under our consideration. Suffice it to say, that there 

 is scarcely any manufacturing process into which water 

 enters at all, in which softness, in a word, the absence of 

 dissolved mineral matter, is not a primary requisite. 



We must, however, refer to the behaviour of hard water 

 in steam boilers, because it is closely connected with, its 

 domestic uses. It is now very widely known that users of 

 steam, who feed their boilers with hard water are much in- 

 commoded by the formation of a deposit, technically known 

 as scale or crock, which attaches itself to the boiler-plates, 

 and something reaches an inch or more in thickness. This 

 means a double loss ; crock is a much worse conductor of 

 heat than is iron, and consequently longer firing is required 

 to get up steam than would be needed with a clean boiler. 

 Further, as the heat of the boiler-plates is not conducted 

 away by immediate contact with the water they are raised 

 to a higher temperature and are sooner worn out. All this 

 we find taking place in tea-kettles, kitchen boilers, and 

 coppers, where there is a hard-water supply. 



Fortunately, in those cases, and they are the majority, 

 where the hardness of water is in great part due to carbonate 

 of lime, held in solution by free carbonic acid, it may be 

 softened by the Clarke process. A quantity of freshly- 

 slaked lime stirred up with water into a cream is added. 

 This immediately seizes hold of the free carbonic acid, and 

 the carbonate of lime thus formed, together with that 

 originally present, subside together, leaving the water 

 beautifully soft, and, to a very great extent, freed from 

 organic matter which may be present. 



This process — " Clarkising," as it is called — is perfectly 

 practicable on the large scale, and is carried out successfully 

 at Canterbury and at Aylesbur}'. The water supply of 

 the latter town is derived from wells in the chalk-beds of 

 the Chiltern Hills, and is to begin with very hard. By the 

 Clarke process it is made one of the finest waters in the 

 world, and fit for any use, domestic or industrial. As col- 

 lected in the store-reservoirs, it displays that beautiful light 

 blueish tint which is characteristic of water very free from 

 organic impurities, when seen in large masses. The 

 colourless appearance of common water is due to the blue 

 being masked by the yellow tint, due to organic matter in 

 solution. 



The experience of such places as Canterbury and 

 Aylesbury proves that the Clarke process might be applied 

 with great benefit to hard water. Unfortunately, the 

 majority of water companies wish to do as little as possible 

 in return for the payments which they receive. 



We now come to a point in water-supply about which 

 there is very little difference of opinion— the presence of 



organic matter. All authorities are substantially agreed 

 that organic matter in water is not desirable, though they 

 may differ concerning the degree of danger which it pre- 

 sents. 



We must here note that even if a water-supply could be 

 found absolutely free from organic matter, and could be 

 brought in that state almost up to the town which it was to 

 serve, it would become polluted, unless it was made to flow 

 through covered channels, and was delivered on the constant 

 system, so as to dispense with that abomination, the cis- 

 tern. All water open to the air becomes contaminated with 

 dust, and to unprofessional minds an account of the com- 

 position of town dust would be anything but appetising. 

 It is nothing uncommon to find in water-cisterns, though 

 the water may be fairly good as it enters, a colony of the 

 wriggling larvae of gnats and midges, some of which are 

 known as bloodworms. All these creatures have the power 

 of setting up putrefaction of a very offensive type, if any- 

 thing is present upon which they can subsist. 



It must further be remembered that water in cisterns is 

 liable to freeze in winter and to become unpleasantly warm 

 in summer. Happy, therefore, in this respect are towns such 

 as Leeds, Halifax, and Manchester, where the inhabitants 

 draw their water for culinary and dietetic purposes, direct 

 from the pipes, without the intervention of a cistern. 



Organic matter is present in water in two distinct states, 

 both objectionable — as lifeless animal and vegetable sub- 

 stances dissolved or suspended in the water and passing 

 more or less rapidly into putrefaction, and as living beings 

 for the most part visible only with the aid of a powerful 

 microscope. These beings, often spoken of as "germs," are 

 for the most part plants — fungi of a very low order, tech- 

 nically known as bacteria and bacilli. They differ very 

 greatly in their properties. All have the power, more or 

 less, of setting up transformations in animal and vegetable 

 matter, dead, or even, under certain conditions, while still 

 living. But while these changes are in some cases harm- 

 less, they are in others, deadly. Experience has taught 

 mankind long ago that " a little leaven leaveneth the whole 

 lump," and on this principle an infinitesimal quantity of 

 these germs, introduced into the body of a large animal, 

 may set up fermentations known as cholera, typhoid fever, 

 dysentery, splenic fever, yellow fever, and the like. Thus 

 an impure water-supply is a common, perhaps the most 

 common, channel by which these forms of pestilence are 

 spread from one sufferer to another. Hence the immense 

 importance of a pure water-supply to every community. 

 The teachings of modern research, chemical and micro 

 scopical, bid us exclude from water intended for the use of 

 man or even of cattle all putrescent or putrescible matter. 

 It is very true that normal sewage may often contain no 

 germs of any specific disease. But if we take our drinking 

 water from a river polluted with sewage or with the drain- 

 age of highly-cultivated and richly -manured lands, we are 

 never safe. 



Hence the water-supply of cities becomes a difficult 

 question. To obtain daily i8o million gallons of a water 

 above suspicion — the quantity requisite for London — is a 

 grave problem. Some sanitary authorities have, therefore, 

 advocated the adoption of a two-fold water supply, the one 

 as nearly pure as possible, to serve for drinking, cooking, 

 baking, washing, etc. ; and the other, of a second quality, 

 for working water-closets, watering the streets, extinguish- 

 ing fires, and the like. For such purposes the water of 

 the Thames would be amply good enough. 



The objections to this double system turn chiefly on the 

 expense incurred both to the owners or occupiers of houses 

 and to the municipal authority. A more serious objection 

 to a dual supply would be the risk of confusion. A careless 



