OF HARD AND SOFT WATER. 105 



For every purpose but drinking, washing our streets and flushing 

 oar drains, and perhaps for a few manufacturing processes, such as 

 paper-making and brewing pale ale, hard water must be softened, 

 and we are therefore naturally led to consider in what way it can 

 be most economically softened. 



The Rivers Pollution Commission of 1868 stated the relative 

 cost of softening water by lime, soda, and soap, to be as follows : — 



1 cwt. of quick-lime .... 

 4f cwt. of carbonate of soda at 1 2s. 2d. 

 205- cwt. of hard yellow soap at £2 6s. 6d. 



The cost of the coal required to soften the same quantity of water 

 by boiling in an ordinary kitchen boiler they estimated to be at the 

 rate of 7s. 6d. for eveiy 9s. expended in soap, or £;i9 4s. 8d. (See 

 ' Keport of the Commission,' pp. 204, 205.) 



These figures do not, however, quite tally with some other 

 statements in the Commissioners' Report, and the cost of coal, 

 soda, and soap is now much less than it was at the time this 

 enquiry was being made. A fairer estimate, for the present time, 

 of the quantities and cost of these different materials required to 

 reduce 100,U00 gallons of water from 20° of hardness to 6°, or by 

 14°, which is the extent of softening which would probably be 

 deemed adequate for the Watford water, would be as follows : — 



H cwt. of quick-lime at 8d. per cwt. 



5 cwt. of carbonate of soda at 3s. 8d. per cwt. 



2 li cwt. of soap at 21s. per cwt. . 

 25 tons of coal at 16s. per ton 



Even at these much-reduced prices of soda, soap, and coal (the 

 Commissioners estimated the cost of coal at Is. 6d. per cwt. or hOs. 

 per ton), it will be seen that the cost of softening water by car- 

 bonate of soda is 18 times that by lime, that the cost of softening 

 it by boiling is 400 times that by lime, and that the cost of 

 softening it by soap is 450 times that by lime. 



Lime, therefore, completely puts out of court the other three 

 agents by which water is usually softened. 



There is yet another, and a very efl'ectual, method of softening 

 water to be mentioned, and that is by distillation, but this is a very 

 expensive process, distilled water requiring for its production the 

 consiimption of about one-tenth its weight of coal. This is e(iuiva- 

 lent to the consumption of a pound of coal for every gallon of 

 softened water. Distilled water is the softest that can be obtained, 

 and if aerated is perfectly wholesome and pleasant to the taste. 



While soft water is undoubtedly the best for every purpose we 

 have yet considered, whether soft water or hard water is best for 

 drinking is not easily determined. Statistics of the death-rate in 

 towns have frequently been brought forward as bearing upon this 

 point, and the result is almost invariably that the rate is a little 



VOL. VIII. — PAKT V. 8 



