A systematic handbook of volumetric analysis, or, The quantitative estimation of chemical substances by measure, applied to liquids, solids, and gases : adapted to the requirements of pure chemical research, pathological chemistry, pharmacy, metallurgy, manufacturing chemistry, photography, etc., and for the valuation of substances used in commerce, agriculture and the arts / by Francis Sutton.
- Francis Sutton
- Date:
- 1882
Licence: Public Domain Mark
Credit: A systematic handbook of volumetric analysis, or, The quantitative estimation of chemical substances by measure, applied to liquids, solids, and gases : adapted to the requirements of pure chemical research, pathological chemistry, pharmacy, metallurgy, manufacturing chemistry, photography, etc., and for the valuation of substances used in commerce, agriculture and the arts / by Francis Sutton. Source: Wellcome Collection.
Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.
400/508 page 384
![its hardness to calcic or niagnesic sulphate {permaneni hardness) cannot be thus softened; but any water Avhich softens on boiling for half an hour will be softened to an equal extent by Clark's process. The hard water derived from chalk, limestone, or oolite districts, is generally well adapted for this operation. To soften 700 gallons of water, about one ounce of quicklime is required for each part of temporary hardness in 100,000 parts of water. The quantity of quicklime required is thoroughly slaked in a pailful of water. Stir up the milk of lime thus obtained, and pour it immediately into the cistern containing at least 50 gallons of the water to be softened, taking care to leave in the pail any heavy sediment that may have settled to the bottom in the few seconds that intervened between the stirring and pouring. Fill the pail again with water, and stir and pour as before. The remainder of the 700 gallons of water must then be added, or allowed to run into the cistern from the supply pipe. If the rush of the water does not thoroughly mix the contents of the cistern, this must be accomplished by stirring with a suitable wooden paddle. The water wil] now appear very milky, owing to the precipitation of the chalk which it previously contained in solution, together with an equal quantity of chalk which is formed from the quicklime added. After standing for three hours the water will be sufficiently clear to use for washing; but to render it clear enough for drinking, at least twelve hour&' settlement is required. This process not only softens water, but it removes to a great extent objectionable organic matter present. The proportion of lime to water may be more accurately adjusted during the running in of the hard water, by taking a little water- from the cistern at intervals in a small white cup, and adding to it a drop or two of solution of nitrate of silver, which Avill produce a yellow or brownish colouration as long as there is lime present in excess. As soon as this becomes very faint, and just about to disappear, the flow of water must be stopped. The carbonate may be removed by filtration in a very short time after the addition of lime, and on the large scale this may be done with great rapidity by means of a filter press, as in Porter's process. This latter method of rapidly softening and purifying water is the invention of J. Henderson Porter, C.E., 1 Tudor Street, Blackfriars, London, whose apparatus is largely coming into use for public water supplies, and for softening waters used in manufacturing processes, and the prevention of boiler incrustations, &c. The chief objections to the original Clark process are, the large space required for mixing and settling tanks, and the time required for subsidence of the precipitate. On the contrary, in Porter's pro- cess, the space occupied is small, and the clarification immediate. The results are admirable, and are achieved at a very moderate cost.](https://iiif.wellcomecollection.org/image/b21443658_0400.jp2/full/800%2C/0/default.jpg)
