OF A SUPPLY OF SOFT WATEB. 119 



■we to manage it ? The simplest answer is by getting rid of the 

 chalk. We have already seen that were it not for the carbonic 

 acid gas in the water there woidd be no chalk, so we may go a 

 step further and say, Get rid of the carbonic acid and the chalk will 

 become insoluble. Of course, if we add sufficient soap we may in 

 time get the water softened, but this is an expensive method, and 

 there are always the nasty curdy compounds formed which get into 

 the pores of the skin in our personal ablutions and clog them up. 

 One well-known method of softening, which I have mentioned 

 before, is by boiling the water for some time. This drives the 

 carbonic acid gas off and liberates the chalk from solution, but to be 

 effective the boiling must last for at least twenty minutes to half- 

 an-hoiir; and there is another objection mentioned by the Chemical 

 Commission of 1851, as follows: — "it is in the more careful 

 washing for the upper and middle classes that the advantages of 

 soft water become fully sensible ; for where a hard water is heated 

 the carbonate of calcium is precipitated on the linen, carrying down 

 with it the colouring matter of the dirty water, and producing 

 stains which there is the greatest difficulty in afterwards removing 

 from the linen. The colouring matter from the water is thus, 

 indeed, fixed upon the cloth by the precipitated calcium salt with 

 the tenacity of a mordant." When, however, the chalk is pre- 

 cipitated by the lime-process which I am now about to mention, 

 this carrying down of organic impurities is a distinct advantage, 

 and I show here a specimen of precipitate derived from hard water, 

 which has taken down with it a considerable quantity of dirty 

 matter much better than any filter would have done. Compared 

 with others the easiest and most economical way of getting rid of 

 the chalk is by the lime-method. 



It may seem somewhat paradoxical to add lime to get rid of 

 chalk, but what we add is quick-lime (the base), which unites 

 with the carbonic acid gas in the water and forms more chalk. By 

 thus giving the gas something else to do it can no longer dissolve 

 the chalk originally held in solution, and both the newly-fonned 

 chalk and the chalk in solution fall down to the bottom of the 

 water, leaving it comparatively free from hardness. How shall we 

 tell when we have added enough lime ? If while we are mixing 

 the lime with the hard water we add it till we get a pale yellow 

 colour with a solution of nitrate of silver, this shows a very slight 

 excess of lime which will quite disappear after the water is allowed 

 to remain half-an-hour longer before being again tested. 



I should like to point out one fact with regard to washing and 

 laundry pui'poses, and that is that we caimot use hard water at all 

 till it has been softened. It must be softened either by boiling, 

 soda carbonate, lime, or soap, and the question that we have to 

 ask ourselves is, Which is the most economical and convenient ? 

 Boiling is neither of these, as it requires time and gives trouble ; 

 soda is expensive ; and soap is both expensive and unpleasant. 

 The lime-method is both economical and gives us a most pleasant 

 water to use. 



