• REPORT OF THE GOVERNMENT COMMISSIONERS ON THE CHEMICAL QUALITY

OP THE SUPPLY OF WATER TO THE METROPOLIS.

[Laid before the House of Commons on the 191h instant.] Thi elaborate and temperate document offers a clear and decided opinion, which is likely to commend itself to the respect and acquiescence of competent scientific chemists,. as well as to the confidence of the pub- lic at large. The following is an abstract under its various heads.

L Chemical Quality of the present Supply.—All the nine Water Com- panies except the Kent (a very small one) derive their supply from rivers fed chiefly from chalk-springs, but including more or less of surface and sewage water. The specimens examined were taken at the end of January, "after moderately rainy weather, with the river full but not flooded." The hardness of the five Companies fed by the Thames was about 14i degrees ; the East London Company' fed by the Lea, 15 degrees ; the New River, fed partly by the Lea and partly by chalk-springs, about the same ; the Kent, 16 degrees. During floods, the Thames water may fall to 8 or 9 degrees. The hardness, except in the case of the Kent, was of a kind that boiling easily reduces. By an hour's boiling, the West Middlesex water fell from 10 degrees to 51 ; the New River, from Al to about 4. The Kent did not soften by boiling.

Seven recommendations to the present supply are specified, and also five objections.

Recommendations. 1. The waters filter well. 2. Being filtered, they are bright. 3. Palatable when cool. (These three recommendations are re- stricted to the ease when the waters are in good condition ; or, as we understand by the sequel, not flooded, nor with much organic matter in them, as in autumn.) 4. The mineral contents of the waters are not un- wholesome. 5. The waters do not act dangerously on lead pipes or cisterns ; neither do they eat out hollows or cause bulky swellings iu the iron pipes, as some other waters do. 6. Being hard, they are less favourable to putre- faction of the organic contents of them than softer waters would be. 7. The Thames offers what appears an inexhaustible source—from 600 to 800 million of gallons daily, or at least twelve times the present demand of the whole metropolis. Objections. 1. The fluctuating temperature ; during the months of June, July, and August, generally above 65' and sometimes above 70'. " This loss of coolness in itself makes the water greatly less palatable, while it pro- motes the decomposition of the organic matter." 2. Under flood, it acquires a yellow colour, 'of an unusually persistent character, and only partially removed by filtration." A pound of alum per 1000 gallons (which would cost about ld.) would indeed remove the colour, but at the expense of some- what preventing the softening of the water by boiling, and converting chalk into sulphate of lime, which is very troublesome in the fur of boilers. 3. "The serious evil" of contamination, more particularly "in the latter past of autumumulthe-early months of winter, from the extensive decompoei-

tion of vegetable matter in the highly-cultivated district through. which the Thames flows." 4. The sewerage. 5. The hardness.

The following quotation will probably be new even to most connoisseurs in tea-making ; and it affords useful information. " Hard water is disad- vantageous for making tea, chiefly, it appears, by requiring. tine beaftba be longer maintained in preparing the infusion. 'lea is habitatally, madsof excellent quality and with economy, in some families, by mcaneof spring- water of a high degree of permanent hardness; but then then:Anon is continued for half an hour, and the temperature maintained near the boiling. point during that period. The tea for the Greenwich Pensioners ieduflised in a large copper, surrounded by a steam case, with water from, e well in the superficial gravel of 24 degrees of hardness, which falls to 18.6 degrees upon. being boiled. But iu the private residences adjoining, it is found necessary to use carbonate of soda for softening, with the same water, in the absence of the efficient means of infusing described. Where any great lose of strength of the tea-infusion has been observed, in passing from a soft to a harder water, it may be probably referred to the circuiustance that the mode of infusing has not been properly adapted to the hard water."

With regard to loss by soap in washing clothes, the Commissioners state it to be inconsiderable in the washing by the poorer classesais conducted in the public wash-houses, for they make use of soda ; but in the washing of finer clothes, where it is desirable to avoid the use of soda, and, also to avoid the boiling of a river chalk-water, the saving in soap would be nearly one- third.

II. Of the Improvement of the present Water Supply.—After adverting to the improvement induced on the present waters by subsidence and titra- tion, the Commissioners advert to Professor Clark's process for softening chalk-water, which it does by removing all the chalk except about 2 grains per gallon. They advert to trials of it on 300,090 gallons of water per day, made at Manchester during the eight previous months, and to five trials, each on more than three millions of gallons, at the Chelsea Water-works.

" The conclusions which were come to both by the engineer and ounselves from these experiments, in which the operation had not the advantage of the efficient means of mixing which might be introduced where it was per- manently adopted, were, that the process falls easily into the nautili° opera- tions of water-works, and is not attended with any peculiar difficulty on the large scale ; and that the softening of Thames water in its ordinary condition by this process to a point under 4 degrees of hardness is perfectly practicable. " The softened water was clear and bright, had acquired no odour nor taste from the process, and could not be distinguished in its sensible qualitis from pure spring-water of equal softness."

They add—" The liming process, even when combined with filtration, proved to be unequal to remove the yellow flood-tinge of Thames.water, nor did it appear to abate an objectionable taste of vegetable matter which the water also then possessed. Had the result been different, the grounds for the adoption of the softening process would have been most cogent. But it seems that it is not to river-waters that this elegant and useful purifying process is most advantageously applicable."

HI. Of the kS'apply recommended by the Board of Health.—The Com- missioners analyzed several of the sand springs, and found them near two de- grees of hardness; but they observed circumstauces in the district that seemed to them to render impracticable the collection of those springs apart from floods and much inferior water that abounds in the district—" water which has been used for irrigation, and also the drainage of cultivated land," . . . . so that "time general supply afforded from this district would not probably fall below 4 to 5 degrees of hardness unreducible by boiling." In this opin- ion they coincide with Mr. Bateman of Mauchester, an engineer euiphiycet by parties wishing to form a company to bring in the same water.

IV. lVhether any Inconvenience would attend the introduction of Soft Ii ater 1—This head is occupied mainly with considering whether soft water would be dangerous by us action on lead. The Commissioners decide in the negative.

V. Of the Water proposed to be supplied fi.om Watford.—Undar this head the Commissioners dwell on the quality and abundance of the °hulk spring- water from near Watford.

VI. Of the Properties to Sc preferred in the Water selected for the supply of the lletropolis.—Under this head we make the following extracts.

" The properties which we would esteem of most value in water to be supplied to the Metropolis are-1. Freedom from putrescible organic matter ; 2. Freedom from constant or even occasional diecolouration by clay and vegetable matter, with perfect brightness and clearness ; 3. Softness ;. 4. Coolness."

"The chalk spring-water unites the greater number of the desirable qua- lities already enumerated. It contains absolutely nothing of organic origin capable of further alteration or decomposition, and is therefore wholly unob- jectionable on the ground of constituents. Its clearness and brilliancy also. appear perfect from the complete absence of suspended mataar,, and are highly attractive. Possessing at all seasons the mean temperature of the year, the same water has an agreeable coolness and freshness, ,Which might certainly be preserved in a great degree by proper means of conveyance and distribution. The only other quality desired in a town supply was softness. The chalk spring-water is not naturally a soft water. In tins respect, it is inferior to the present supply in oue sense, being one-fourth harder ; best after boiling, the advantage is with the spring-water. It is, however, in the facility and completeness of the removal of this hardness, that the supe- riority of the spring over the river water is most apparent. Thu softening operation, by the use of lime, is applicable in all seasons to the spring-water; which indeed adapts itself with singular felicity to that process, the carbo- nate of lime always precipitating with rapidity, and so completely as not to create a necessity for filtration. The chalk spring-waters can thus be CO ra =tided with certainty, under three degrees of hardness, which is probably the extreme limit attainable anywhere in England for a great supply."