All deep subterranean water also ultimately finds its way into the ocean, through subterranean pores, fissures, or channels, often penetrating to great depths before doing so. Thus, at present, a bore-hole at Richmond, in Surrey, derives a supply from the surface carried down to a depth of more than a quarter of a mile below the surface of the ocean. The water from this bore-hole will naturally rise to an altitude of more than 120 feet above Ordnance Datum, or the mean level of the sea.

As a rule, for domestic uses, subterranean or spring water is greatly to be preferred to river or surface water, more especially when it is derived from certain beds of sand, as then the water often possesses the whole of the seven characteristics before described. Large quantities of subterranean water, however, are derived from the chalk formation in the south and south-east of England, and in Yorkshire, and used for the supply of urban and other populations. Thus a considerable portion of inner and outer London, and numerous towns situated on or near the chalk formation, are supplied by subterranean water absorbed by the chalk. Aylesbury, Brighton, Canterbury, Charlton, Deal, Dover, Greenwich, Gravesend, Hull, Margate, Plumstead, Ramsgate, Tring, Woolwich, and many other places, are entirely supplied by spring or subterranean water obtained in this way from the chalk formation. This water has five out of the seven characteristics I have mentioned, but is wanting in two, namely, softness and non-ability to deposit fur when boiled. By a simple process, however,-invented by the late Dr. Clark, and described in a paper read before the Society of Arts on the 14th May, 1856,-both the quality of hardness and the power to deposit fur when boiled are got rid of. The process is a simple one, and has now been in practical use for more than a quarter of a century with great success. Water so treated is greatly admired and valued by those who are supplied with it.

Surface water, whether derived from brooks, rivers, or lakes, though the latter be natural or artificial, is usually

soft, and less liable to deposit a fur when boiled than most spring or subterranean water. On the other hand, it is not well adapted or so wholesome for drinking; (3) it is cold in winter and liable to freeze in distributing pipes; warm in summer, and (7) pervaded by numerous living organisms.

(5.) It is not always clear and bright without being filtered (2) and dissolves lead.

Thus, in these most important respects, spring or subterranean water is to be preferred to river, lake, or surface water. Those who care to follow this subject more in detail, will find both the quantity and quality of spring or subterranean water fully discussed in a paper I read before the Society of Arts on the 31st January, 1855.

It is obvious, also, that all brook, river, or lake water is liable to be greatly contaminated by becoming mixed with faded blossoms and fallen leaves; by mud, mainly composed of decaying vegetable matter and pervaded by numerous living organisms; by manure from off the land; by the excreta of fish, animals, and man, both liquid and solid, washed into it, and more especially in times of floods; by the action of frost and other contaminating causes that it would be difficult or impossible to prevent. Indeed, streams and rivers, in a greater or less degree, must always remain the sewer of a district, and the means by which surface washings are conveyed to the ocean.

All river, lake or surface waters, more especially in warm seasons of the year, are found to be pervaded by minute living organisms, vegetable and animal, none of which are found in uncontaminated spring water.

A paper read by Mr. Jabez Hogg, before the Society of Arts, on the 12th May, 1875, will be read with interest by those who care to pursue the subject.

In the Parliamentary Session, 1852, a body of householders deposited plans, and applied to Parliament for powers to supply a large portion of London with softened spring water at a very moderate charge for drinking and personal ablution, thus leaving the old-established com

panies who supplied the Thames water to continue the supply of such water for watering roads, for flushing sewers and closets, and for other gross purposes. At that time, however, the Water Companies had great influence in the House of Commons, so much so, that the Government of the day, very much, as I know, to their regret, felt themselves obliged to exert their influence to prevent the powers sought being granted, in order to secure the passing of a Government measure affecting Imperial interests.

As respects the metropolis, no physical difficulties exist to prevent the whole of the four millions of souls inhabiting the inner and outer circle from being copiously supplied with uncontaminated softened spring water, possessing all the seven characteristics I have named. Indeed, a considerable portion of the inner and outer circle is already supplied with uncontaminated spring or subterranean water, though not (2) of a soft character or (6) free from depositing a fur when boiled.

It is not from want of ability to supply the metropolis most abundantly with subterranean or spring water possessing all the seven characteristics that the inhabitants are not so supplied. The want of an uncontaminated supply to the greater portion of the inhabitants mainly results. from want of the necessary technical information among these who have to put up with the present supplies.

Such Conferences and discussions as these we are now concerned with cannot fail to afford much useful information to many, and it is to be hoped will ultimately result in securing a more wholesome, a softer, and a cheaper supply carried into the dwellings of the mass of the population.

SOFTENING OF WATER.

By BALDWIN LATHAM, M.Inst.C.E., F.G.S.,

F.R.MET.SOC., &c.

FROM the remotest period of antiquity, of which we have any record, the art of softening water for the purposes of washing and cleansing, appears to have been known and adopted. Long anterior to the invention of soap, of which the elder Pliny gives us the earliest account, as having been first manufactured by the Gauls, caustic alkali derived from wood ashes, and from natural earths, was used as a lye. The process of making an alkaline lye was mentioned by Aristophanes (434 B.C.), and also by Plato (348 BC) We have also a record in the volume of Sacred Writ, in Jeremiah ii., verse 22: "For though thou wash thee with nitre and take thee much soap." The Hebrew word both used in this passage is stated by authorities to refer to the vegetable lye of potash, but in another passage of Sacred Writ, Malachi iii., verse 2, where reference is made to "fuller's soap," the Hebrew word nether is there believed to apply to a mineral lye or soda. The people of Egypt were known to use mineral alkali and ashes of plants for the purpose of making a lye for washing from an early period as recorded by Pliny.

Nitrum, a natural lixivious salt which is found in many southern countries, was well known, and was used for washing at a very early period. Certain plants, too, the juice of which is of a saponaceous nature, were used in early days, instead of soap. Meal and many kinds of seeds and bran were also used in connection with washing operations. The urine of various animals kept until it became stale and alkaline was used in eastern countries at a very early period; and in the Avesta, special directions are given for cleansing and purifying with the urine of the

There is nothing harmful in this colouring matter, because it is of purely vegetable origin, and to some extent it may be removed by storage in open reservoirs, or running in open channels exposed to the air.

Many towns are so located in this country that it is practically impossible that they should obtain pure water supplies from elevated water-sheds, on account of the enormous expense that would be entailed in the construction of the necessary works. Such places must be content to be supplied from rivers in their immediate neighbourhoods, and which, having run their courses through many miles of highly manured lands and past thickly populated towns and villages, contain water which has necessarily become polluted by the washings from the lands and the sewage from the towns. Such sources as these would be inadmissible, but for the great rehabilitating process which nature silently carries on in a river, and to which chemists apply the term "oxidation." In this wonderful process, the polluting organic matters which the water contains are converted by the agency of oxygen into harmless inorganic salts, and the water again becomes fit for the use of man.

This statement must, however, not be made without some reservation and explanation, because chemists of the very highest standing are not agreed as to the extent to which rehabilitation of the water is carried. This has, in fact, become quite a burning question, and the battle has been fought long and frequently over the water which is taken from the Thames, and delivered for consumption by the inhabitants of London.

The difference of opinion is now narrowed down into a small compass, and to outsiders it would appear that there is a chance, sooner or later, an agreement may be come to between the authorities.

As representatives of the two sides may be named Dr. Frankland and Dr. Meymott Tidy. Dr. Frankland admits that oxidation is effective in burning up, or converting into a harmless condition, even such vile contaminations as