Page images
PDF
EPUB

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 B.C.).

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 borith 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 sacred cow. Pliny, in his 'Natural History,' states that if water be nitrous or brackish, or bitter, if some fresh barley meal is put into it, that within two hours it will be so amended and sweet that a man may drink thereof; and a translation made from Pliny, by Dr. Philemon Holland, in 1634, goes on to recount that the same operation of sweetening water may be effected by a kind of chalk which is found in the island of Rhodes; and a description of clay which is found in Italy will do the same. Pliny, who died A.D. 79, records the manufacture of soap as being composed of tallow and ashes, the best being made of goat's suet and beechwood ashes. That the amount of mineral matter in water, as affecting the conditions of health, was studied at a very early period, is known from the fact that the hydrometer was probably first used for the purpose of ascertaining the quality of the water used for dietetic purposes. Although the principle of the hydrometer has been ascribed to Archimedes, there is no record of this instrument having been made by him. The earliest record, according to Beckmann, appears from a correspondence between Synesius and Hypatia, the latter of whom was assassinated, A.D. 415, in which Synesius states that he found himself so ill that he proposed to use the hydrometer, and requested Hypatia to at once procure one for him. The mode of strengthening ordinary lye by the addition of lime was known in the time of Paulus Ægineta, a physician who flourished either in the 3rd or the 7th century.

Soap is mentioned by Geber in the second century, and at a later period is frequently referred to by Arab writers, as being used not only for detergent purposes, but also for external application.

Soap is very largely used, or rather wasted, in many places in the present day for softening water. It is now well understood that no useful effect in washing is produced until sufficient soap has been used to soften the water.

For the purposes of this investigation, water may be divided into two classes, hard and soft. Hard water is a water which contains salts of lime, magnesia or iron, and

sometimes an amount of free carbonic acid. A hard water, commonly considered, is one that destroys soap in washing, while a soft water is one that does not destroy soap. A soft water may derive its properties from an absence of earthy salts, or it may have become soft by reason of the presence of certain alkaline salts in the water, notably the salts of soda and potash.

Hard waters may be divided into two classes, those which are permanently hard and those which are temporarily hard. It is often found that a single sample of naturally hard water partakes of both these properties. A water which is said to be temporarily hard becomes soft by boiling, as the hardness is due to salts of magnesia or lime dissolved in the water by the agency of carbonic acid, or due to the presence of this gas in a free state in the water. Under either circumstances, the effect of boiling the water a sufficiently long time is to drive off the carbonic acid gas. and a natural softening of the water takes place from the absence of this gas, and the earthy salts that have been held in solution by it in the water.

Water that is permanently hard derives this property from the presence of the same salts as render water temporarily hard, but instead of being combined with carbonic acid, they are combined with sulphuric acid, and to soften water that is permanently hard requires very different conditions than is the case with waters that are only temporarily hard.

The qualities of a good drinking water have been described as :

Ist. Freedom from vegetable and animal matter.
2nd. Pure aëration.
3rd. Softness.

4th. Freedom from earthy mineral or other foreign matter.

5th. Coolness and delivery at the minimum temperature. 6th. Lucidity or clearness. 7th. Absence of taste and smell. Although many authorities insist that for the sake of

« EelmineJätka »