[50] It has been alleged that, by the use of soft water, the saving in soap would probably be equivalent to the whole of the money at present expended on water-supply; and that in the article of tea, the economy would amount to about one-third of the tea now consumed in the metropolis. It strikes me as possible that, in forming these estimates, the argument may have proceeded too much from a consideration of the hardness of London waters in their unboiled state; and that sufficient allowance may not have been made for the change which boiling produces. If boiling were prolonged for some hours before culinary or detergent use of the water, the results (for tea or soap) would be identical with those produced under the employment of soft water. Notoriously this precaution is not taken: but to avoid disputable ground, I confine myself to _the fact of considerable pecuniary loss_, arising from the cause in question, and I avoid any attempt to determine its exact amount. The chemical constitution of these waters occasions another inconvenience. Their carbonate of lime is held in solution (in the chemical form of bicarbonate) by an excess of carbonic acid: under the influence of heat this excess is gradually disengaged and driven off; consequently, as they approach the boiling point, they begin to precipitate the earthy salt which that gas was instrumental in dissolving. Each gallon of water under these circumstances would deposit from ten to fifteen grains of earthy matter on the interior of whatever vessel might contain it, or on the surface of whatever solid--linen or mutton, might be contained in the boiler. Hence arises the well-known _furring_ of vessels in which such waters have habitually been boiled. I refrain from dwelling on the economical considerations which arise in these points of the subject, as very obvious inferences from the result of chemical analysis; and I pass to other matters more strictly within my own province of observation. Is water thus constituted in any degree detrimental to the health of those who drink it? It is not in a single word that this question can be fairly answered. Almost insuperable difficulty belongs to it, from the absence of any statistical method by which we might isolate the water-drinking portion of our population, and might compare them, in regard of the diseases to which they are liable, with similar sections of population in soft-water districts and in harder-water districts. Obviously, no other method of comparison can be unobjectionable; and, in arguing the subject from such materials as I have, I can pretend to nothing more than a rational approximation to truth.