of soap destroyed by a measured quantity of the water, and then to state the results as the amount of carbonate of lime which would destroy that quantity of soap."

Thus water which does not form a suds or lather, curdles, and so wastes the soap. This curd is a precipitate formed by the combination of the soap with the lime and magnesia in the water.

"The hardness has much significance upon the economic side. Hard water is objectionable for domestic purposes, in washing, and for manufacturing purposes in boilers. Linen cannot be washed with hard water, and other materials not as well as with soft water. With regard to its effect upon health, the English Commission took a great deal of testimony. (Sixth Report, pp. 184 to 194.) One witness said that soft water was more conducive to health, as people were more apt to be cleanly when they had soft water to use; another that lime-sulphate in the water appeared to disagree with some persons; another that the death-rate was apparently a little lower in towns supplied with moderately hard water. About ten to fourteen degrees of hardness per gallon (fourteen to twenty per hundred thousand), was deemed by some to be beneficial. The question of the connection of the hardness of the water with the death-rate was investigated, and from numerous statistics taken in the United Kingdom, it was found that there seemed to be no necessary connection. The conclusion of the commission was, that though there were some differences of opinion 'there is almost absolute unanimity as regards the wholesomeness of soft water.' Popular prejudice runs in the same direction, especially when comfort in washing, and economy of soap and boilers are taken into consideration, while for sanitary purposes no objection can be urged to the use of soft water, other things being equal."

As all the water in the limestone regions of this State, and much of that in the red sandstone and some in other parts is hard, we need to be fully aware of its effects. Boiling removes the temporary hardness, but not that known as the permanent hardness. A process known as the Clark process remedies the former, but not the latter, and so becomes a test between the two. This permanent or unremovable hardness, if of much amount, renders the water undesirable for drinking purposes, although it can be reduced by carbonate of soda. The greater the permanent hardness the worse the water. By permanent hardness it is not meant that no chemical process will remove this hardness, which comes mostly from the sulphates (as gypsum, etc.) Distillation and sufficient quantities of soap or carbonate of soda will remove this. But the process is expensive and complicated, and so it

has been called permanent hardness, in contrast with that easily removable. Although most of our hard waters contain, in addition to the carbonates, some of the sulphates, yet when the former is removed they are greatly improved for cleansing purposes.

"Every degree of hardness means that one gallon of water contains one grain of carbonate of lime (common chalk); there are 7,000 grains in a pound weight; therefore, 7,000 gallons of water of one degree of hardness would contain 1 b. of carbonate of lime, and that would waste 8 lbs. of soap. But nearly all waters, except rain-water, are much harder than this, their degrees reaching 10, 15, or 20, so that if we were dealing with a water of 20 degress of hardness, our 7,000 gallons would waste 170 lbs. of soap. This quantity of water would easily be used in a year by a family of say seven persons, if we include the washing of clothes, so that, with soap at only 3d. a pound, we have a pure loss of 438. per annum in this item alone, or an amount equal to the income tax upon £100. There is also to be added loss caused in cooking, making tea, &c. For persons who get their living by washing, the importance of using soft water is very obvious."

AS TO THE REMOVABLE HARDNESS.

"To determine whether water is hard, we take a gill or thereabouts in a flask and add to it a clear solution of soap in alcohol. If the mixture is then shaken and remains clear with an abundance of soap bubbles over it, the water is soft, but if it becomes white, and curdylooking masses form and float in it, and no bubbles appears on the surface, it is hard water.

"The hardness is caused by salts of lime and magnesia which are in solution in the water. These salts render the water unfit for washing, as they destroy soap, and they are troublesome in tea kettles and in steam boilers, on account of the incrustation which is formed as the water boils away. But hard water is not specially unwholesome, and it is common to find well-waters containing from 10 to 60 or more grains of solid matter to the gallon, which have been used for years without any injurious effect, though sanitarians recommend that water containing more than 17 grains to the gallon be not used.

Hardness implies one grain of bi-carbonate or sulphate of lime in a gallon of water. Water at or below six grains of hardness to the gallon is not objected to. The report of the State Geologist makes ten grains of hardness to the gallon the limit. Whether the removable hardness injures health cannot always be determined, but as it may cause dyspepsia, diarrhea and calculus, and adds a material not

needed for digestion or assimilation, it is better to use the softer water. The incrustation of boilers by hard water and, which is much worse, from the sulphate hardness, and the great wastage of soap caused by it, are worthy of great economic consideration. The water of Worthing, in England, for instance, is so hard that in one thousand gallons of water twenty-eight and one-half pounds of soap are destroyed or curdled before any lather will come. In the Thames water it is over two pounds, in that of Manchester only about three pounds, while in the Loch Katrine supply of Glasgow it is only two-fifths of a pound. It is easy to see that if such large amounts of soap are thus wasted, and if there may be some peril to health, the hardness of water should be considered in its introduction or remedied afterward. Water kept boiling about a half hour loses most of this removable hardness. Such water, poured on thin slices of well-burned toast, is found to agree with some who, from stomach or kidney disease, are susceptible to mineral ingredients. The Clark process, as described by Church, is thus carried out by the East London Company:

"Slake 18 ounces of freshly-burnt quicklime in a little water: when the lime has fallen to powder, add enough water to make a thin ream with this powder, and stir the mixture in a pail. Then pour this cream into a cistern containing 50 gallons of the water to be softened, rinsing the pail out with more water, but not pouring out any lumps of lime that may have settled. Let into the cistern the remainder of the 700 gallons of water which 18 ounces of lime can soften, and take care that a thorough mingling of the water and lime occurs. The added lime seizes the carbonic acid gas which held the carbonate of lime in solution, and so both the original carbonate of lime and that formed in the process fall together as a white sediment. This takes some time to settle-from 12 to 24 hours-but the water may be used for washing before it has become quite clear. This process is carried out on a large scale at Canterbury, Tring and Caterham. At Canterbury 110,000 gallons are softened daily by the addition of 11,000 gallons of lime water, the total impurities of the water being thus reduced from 23 grains per gallon to less than 8. And not only are hardening matters thus removed, but organic substances as well. The process purifies, to some extent, as well as softens; and the method is not only effective, but cheap. It would require 201 cwt. of soap, costing £47 18. 8d., or 4 cwt. of carbonate of soda, costing £2 178. 6d., to soften the same quantity of water which could be treated by Clark's process for 8d., the cost of 1 cwt. of quicklime. "The hardness of water is a great defect. Already we have shown some of the drawbacks to the use of a very hard water: others may

be named. In preparing articles of food by boiling them in water, we find that they do not get so well done in hard water as in soft; indeed, it is a good plan to boil the water first before using it for such purposes. Greens, boiled in hard water, acquire a dull gray color, as the earthy matters of the water are deposited upon them. If they are cooked in boiling water, which has also been boiled some minutes before, and especially if a small pinch of carbonate of soda and a little salt be added, this defect will be remedied. For making tea with hard water, it is allowable to use a little carbonate of soda, but a great deal too much is commonly employed. For cleansing the skin,. hard water is not nearly so efficient as soft."

Thus we claim that all water extensively used should be tested both as to its total, its removable and its unremovable hardness. Where any other inorganic or mineral ingredients of water are suspected to be present in undue proportions, they may be detected by further analysis. In the cretaceous formations of the State, iron pyrites or copperas (sulphate of iron) are common, and the water often has a slightly astringent taste and blackens tea. Soms of the waters are blackened by peat or by the cedar beds of some swamps. It has been claimed that the slight amount of iron and of cedar and pine present in some waters of the State exercise antiseptic powers and so prevent disease.

It is encouraging that there is in every part of the State so much attention now given to inquiry as to sources of water-supply. Yet it is evident that each family needs for itself to have a certain amount of knowledge as to possible sources of pollution. In the case of cisterns, springs, shallow or deep wells, we need to know that they are so made and used as not to expose them to contamination such as is generally an extra demand on the vital forces and too often causes actual disease and premature death.

ON FILTRATION.

PROF. GEORGE H. COOK.

By filtration, I understand the clarification and purifying of water for culinary and household use. The rapid increase in population, and the great number of manufacturing establishments, all over our Eastern States, is every year rendering the stores of water in the ground, and the streams which flow from the surface, and even the rain which falls from the clouds, more impure. Our well-waters, our lake and river-waters, and even our cistern-waters, are liable to be contaminated with inpurities some disagreeable, others dangerous, and all undesirable-and yet from one or other of these we must get our supplies.

How shall we accomplish this end, and at the same time get our supplies pure and wholesome? The answer, in general, must be, by filtration.

The term filtration is by some understood to mean only the straining out from a fluid such particles of floating solid matter as renders it roily or otherwise objectionable in appearance, while others understand by it the removal, not only of the solid floating particles, but also the substances which may be dissolved in it. The first can certainly be done, and the other only to a limited extent.

Water, to be wholesome and acceptable, should be clear and colorless; it should also be free from any organic matter, especially that which is of animal origin, but it is not necessary that it should be entirely free from mineral matter, such as the salts of lime and magnesia, which give the hardness to water. Hard water, even up to that containing fifty or sixty grains to the gallon, is not unwholesome for drinking, though it is very unfit for washing or for making steam. Water which is made hard by the presence of carbonate of lime, may be made soft by the addition of a proper quantity of quick-lime; but sulphate of lime, which causes the hardness in most of the waters of this country, cannot be economically filtered out or separated.