ON THE PURIFICATION OF DRINKING WATER. 257 
£63,000 (being ten per cent, on the estimated value of the 
soap and soda consumed) is, we believe, all moonshine. 
The washing of clothes, as practised by our metropolitan 
nymphs, is usually affected by hot, not by cold water ; and 
as by boiling, the same softening effect is produced on water 
which Professor Clark proposes to obtain by his patent 
process, the London washerwomen already adopt as good 
a process without the payment of anything for the use of a 
patent. 
Lastly, the complaints made respecting the quality of the 
water supplied by the metropolitan companies apply to the 
organic matter chiefly, rather than to the earthy salts. For 
though Thames water contains on an average about four- 
teen per cent, of calcareous salts, yet the greater part of this 
is bi-carbonate of lime, which by boiling is decomposed as 
explained above. Now, as in washing, brewing, tea- 
making, &c, the water is usually boiled before it is used, 
the inconvenience produced by the bi-carbonate is but little 
felt; and the real complaints relate to the suspended or 
mechanical impurities, and to the dissolved organic matter. 
d. Addition of Oxalate of Potash .—Mr. Horsley, a re- 
spectable Pharmaceutical Chemist of Ryde, Isle of Wight, 
has taken out a patent for a new method of preventing 
incrustations in boilers, and also for purifying, filtering and 
otherwise rendering water fitter for drinkable and other 
purposes. When sea water is employed for generating 
steam, he purifies it by employing oxalate of potash and 
ammonio-phosphate of soda ; and the proportions which he 
employs for the water of the British Channel are about two 
drachms of oxalate of potash to about two ounces of the 
ammonio-phosphate of soda for every gallon. When his 
object is to purify and soften hard water he employs such 
substances as are capable of decomposing the calcareous 
salts, such as calcined or caustic baryta, or baryta water, 
phosphate of soda, silicate of potash, oxalic acid or the 
oxalates, and caustic strontia, or strontia water; but he 
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