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A simple calculation shows that 10 degrees as grains per gallon 

 correspond to 14.3 degrees expressed as parts per 100,000. 

 Theretore it is insufficient to be told that a water is of 10, 15, 

 or 20 degrees of hardness; we must also know whether this 

 stands for grains per gallon or parts per 100,000. To convert the 

 first into the second, divide by decimal 7 ; to pass back to grains 

 per gallon, multiply by decimal 7. As kk grains per gallon" are 

 slowly disappearing simply as one of the many results of the 

 advent of the metric system, and most analyses made to-day 

 are expressed as parts per 100,000, it is obvious that an analysis 

 so expressed has a much wider field for comparison. 



Adopting this form of expression, the average total hardness 

 of our water is just 15 degrees. In grains per gallon this will 

 be 10| degrees. This figure is the average of 15 determinations. 

 The greatest hardness I have observed was on the 8th of last 

 month (February, 1918), when it rose to 17J degrees. The 

 lowest — 13.6deg. — I found on the 6th of last June. Just at 

 present (March 2nd, 1918 )the hardness is at the average value.* 



There is no law 7 of the country that says that waters shall 

 not exceed such and such a degree of hardness, but when a com- 

 pany is being formed and is applying to Parliament for the neces- 

 sary powers, local authorities may obtain the insertion ol a 

 clause in the Bill stipulating that the water shall be softened 

 ■down to a certain degree and must not be allowed to exceed that 

 hardness. I think that our water company are under such an 

 obligation to soften down to 10 grains per gallon, which as parts 

 per 100,000 is 14.3 degrees. This exceeds the average value 

 found by only half a degree or so. It seems therefore thac they 

 are keeping to their undertaking, and that the complaints of the 

 excessive hardness of the water are quite unjustifiable. In a 

 moment we shall see that the inhabitants of Poole and of Christ- 

 church and part of Southbourne, who are supplied by other com- 

 panies, have more right to complain. 



Our water owes its hardness to salts of calcium — the sul- 

 phate and the carbonate or, more correctly, the bicarbonate — 

 and is almost completely devoid of magnesium salts. On boil- 

 ing, nearly the whole of the chalk is precipitated, yielding a water 

 the hardness of which averages 4.4 degrees, and is subject to 

 less variation than the total hardness. This might have been ex- 

 pected, as any irregularity in the softening process affects the 

 total hardness, but the amount of salts remaining after boiling 

 are only affected by variations in the original water, and not by 

 the ordinary lime softening process. The calcium sulphate 



"*The average hardness yielded by weekly determinations extend- 

 ing from February 5th, 1918, to December 6th, 1918, is 

 15.6 parts of Ca()0 3 per 100,000. The highest figure was 

 obtained on October 4th, when it was 20.2deg. The lowest 

 occurred on July 26th, and was 13.6deg. 



