The scheme has suffered no loss from the closing out of the first -contract, further than some unavoidable delay in time.

manner.

In August, 1890, the Commissioners let a portion of the work to the Morris & Cumings Dredging Company, of New York city, who have commenced operations, and are progressing in a very satisfactory From the well-known reputation of this company, which is largely engaged in government and municipal work in various parts of the United States, there is every reason to expect that the work they have in hand will be pushed to a speedy and successful termination.

The plans for the gates in the Beattie dam have been decided upon, and they will be erected, and the lowering of the dam will be effected, as soon as the necessary excavations shall have been made.

The present contract will probably be completed early in the coming year, and it is hoped that the work on the upper reaches of the river will be begun before that time, so that some beneficial results may be secured next year.

The expenses of the scheme are to be assessed, after completion, upon the lands benefited. In the meantime, funds are raised for carrying on the work by the sale of Commissioners' bonds, bearing six per cent. interest, and payable in the year 1900. No difficulty has thus far been met in securing necessary funds by the sale of these bonds at par. That they are a thoroughly safe investment, has been amply proved in the case of the Pequest river drainage, in Warren -county, a few years ago, where a similar scheme was carried to a successful completion under the same general drainage law.

SEWAGE DISPOSAL.

The question of the final disposal of sewage is one fraught with such weighty consequences as to be well worthy of the frequent consideration given it. While there is abundant evidence that rapid streams, flowing over rocky beds, containing little of vegetable and organic compounds, and having abundance of air, sunlight, animal and plant life, will, in addition to dilution, dispose of large quantities of sewage matter, there are many streams into which too much sewage is cast. The use of small brooks and ditches for such a purpose is indefensible.

There are also many places where sewage must have some other disposal, as with inland towns. Growing importance is being attached to methods of sewage purification, since thus streams can be often relieved of a superabundance of decomposable material, and inland cities can be provided for. So long as it is shown, by careful calculations, that "the sewage of English cities contains only from one to four cents' worth of fertilizing matter per ton, and a ton of Boston sewage about one cent's worth," we need not, in this country, expect much from plans for the utilization of sewage. Where sewage cannot be disposed of, in its crude state, into very large rapidlyflowing streams, the three great plans of dealing with it are by chemical purification connected with subsidence, by irrigation, and by intermittent downward filtration, or by these, to some degree, combined with each other.

I. As to chemical purification in any of its forms, it is expensive, and does not give a perfect effluent. Yet, as urged in previous reports, it is often of great service, as enabling a portion of offensive material to be separated and converted into sludge or compressed cakes, and so permitting the remainder to pass into streams or to be otherwise disposed of. It is not necessary to discuss the more than 450 patented processes, and several of the best, which are not protected by patent. Electrical purification is one of the forms of chemical treatment which has come into more recent use. Chemical treatment is recommended and carried out on a large scale, as in Milwaukee, Providence and East Orange, where, for lack of suitable land area, irrigation or downward filtration would not be feasible. In the Providence report, the expense of intermittent filtration is stated at $28,000 per year, as against $65,000 by chemical precipitation, and yet preference is given to the latter, because of the expense of land, &c. Some of the more recent devices are well noticed, as follows, in an article by Prof. Henry Robinson, of the Mechanical Institute of Civil Engineers, England:

Mr. William Webster has devised a system of purification of sewage by means of electrolysis, which I have seen in successful operation at the Crossness outfall. The principle consists in breaking up the organic compounds of sewage into their constituent parts, by passing an electric current through iron electrodes, which results in the formation of iron oxides and chlorine. The first produces oxygen and the second produces chloric acid, which destroys organic matter.

A non-oxidizable carbon plate is employed for the positive pole, and iron is used at the negative pole, so that by means of a porous diaphram between, the component parts of the mineral salts are collected. At the non-oxidizable plate a solution of chlorine and oxide of chlorine is produced, and at the negative plate ammonia, soda and potass are formed, which precipitate the magnesium salts and lime in the liquid. A large portion of the solid and dissolved impurities in sewage is thus deposited in the form of sludge. The process, which is one of much scientific and practical interest, is now under investigation by the officials of the county council. Mr. Webster has also arranged an electric filter for the purpose of treating the effluent where a higher degree of purity is required. He applies the electric current to a carbon filter, the carbon being the positive pole; the nascent oxygen produced in the pores of the carbon by the current destroys organic matter in the liquid, and at the same time preserves the filter in a clean state. This system is obviously applicable to the filtration of domestic water. M. Hermite (of electric bleaching notoriety) is employing, at Rouen, a battery of electrolyzers (with anodes of platinum and kathodes of zinc), to produce a deodorizing and disinfecting action upon sewage. He passes the sewage through a battery of this kind containing common sea salt, in the proportion of 70 to 350 grains per gallon.

"Webster's process is intended to take the place of the purification of sewage by chemicals involving three processes, precipitation, oxidation, and disinfection, attended with the disadvantage that if too many chemicals are used fermentation in the river may take place. The principle of the electrolytic system is that the compounds always present in sewage are split up into their constituent parts by the electric current, passed through iron electrodes. At the positive plate chlorine and oxygen are set free, and combine with the water and the iron plate to form acids which act powerfully upon the organic matter. A flocculent precipitate of the impurities in suspension and in solution is formed, which, after being first carried to the surface by the hydrogen generated, gradually settles to the bottom, leaving a perfectly innocuous effluent. The effluent can, indeed, if sufficient electric power be used, be converted into an absolute disinfectant. The plant set up by Mr. Webster, at his own expense, for the purpose of experiment, consists of an engine of 20 horse-power, and a dynamo capable of developing 43 horse-power, together with a wooden shoot fitted with iron electrodes. The sewage is pumped by the engine (which also drives the dynamo) into the shoot, and in traveling along it (shoot) every particle of the sewage is brought into direct contact with the plates or electrodes. The fluid passes from the shoot to the tanks, where the precipitate of suspended matter or sludge, as it is termed, settles at the bottom in about two hours, the effluent being afterwards drained off. The electrodes are made of cast iron, and those in the shoot are divided into twelve sections, which can be con

nected either in series or in parallel. When once the necessary plant, which can be adapted to any existing tanks, has been set up, the only outlay involved by the process, beyond the ordinary working expenses, is in the renewal of the positive electrodes, for these are acted upon by the acids formed. It is calculated that to treat a flow of ten million gallons of sewage a day, the consumption of iron should not exceed four hundred and seventy tons per annum, while the mechanical power required would be 8 horse-power per three hundred thousand gallons. These calculations are based on London sewage, which is often diluted with rain-water. But where the sewage is stronger, the power employed need not be so great, because the chlorides which form the precipitating agency would be present in greater proportion to the volume. It is estimated that the working cost of the electrolytic process when applied to a large volume of sewage would be about thirteen shillings per million gallons, and that the whole sewage of London might be treated for about thirty-six thousand pounds a year. Taking into account depreciation of plant, interest on capital, &c., the amount would probably be within fifty thousand pounds.

Engineering, at the conclusion of a long and favorable notice of Mr. Webster's electrolytic system, says: "There is a charming simplicity about Mr. Webster's process. He manufactures his chemicals, to a great extent, out of the sewage itself, and he uses them in the nascent state, when it is well known they are most powerful. Instead of adding five, ten, twelve or fifteen grains per gallon of solid matter, as is now done, he only adds two, and he not only precipitates the matter in suspension, but he also removes some of the organic matter in solutiou. This latter is an important matter, as it defers the second decomposition so long that the effluent may be carried down to the sea, or oxidized by natural influences, before it can occur. extent to which the purification can be carried is merely a matter of time, and in hot weather, when the quantity of sewage is reduced and is consequently fouler, it can be allowed to remain for a longer period in the electrolytic bath.""

The

Prof. Robinson also details his investigation of the precipitating and filtering materials which are employed at Acton and Hendon by the International Sewage and Water Purification Company. The process consists in first precipitating the bulk of the suspended, and some of the dissolved matters, by means of what is termed "Ferozone" (it was formerly called magnetic ferrous carbon), and in passing the effluent through a filter containing a material named polarite. The essential difference between these two materials is that the precipitating substance (ferozone) which is mixed with the sewage, contains mainly sulphate and magnetic oxide of iron rendered soluble, whereas

the filtering substance (polarite) is composed of more than 50 per cent. of magnetic oxide of iron, with silica, lime, alumina, magnesia and carbonaceous matters which are absolutely insoluble. These materials are manufactured from natural deposits which are found in the anthracite coal formation. The main features in this process are as follows: So far as the first part is concerned, the precipitating action is produced without the aid of lime. At Acton, about eight grains per gallon of sewage are employed, and from one to three hours' rest are allowed. Clarification and deodorization are thus effected, and the deposited sludge (when pressed into cakes in the usual way) is found to have a manurial value which leads to its being purchased and used upon land. The next part of the process consists in passing the effluent from the precipitation tanks through a layer of the other substance (polarite), and it is necessary to place above it a stratum of sand or other material (the surface of which requires occasional raking over), to intercept any suspended matter which would clog the pores of the filter and interfere with its action.

The effect of the polarite is singular, and appears to be unchangable, at least no alteration in its efficiency has been found after fourteen months' use at Acton, according to a report by Sir Henry Roscoe ; a longer experience elsewhere is stated to give the same results. This filtering material thus discharges an important function in sewage treatment, as it serves in lieu of a much larger area of land, or of an artificial filter, such as is often made by alternate strata of burnt clay or alluvial soil. The explanation of the action of polarite is that it liberates from its microscopic pores large volumes of oxygen, which attacks and destroys organic impurities. The magnetic spongy iron which came into use some years ago for purifying water was found to rust and cake; polarite, however, is remarkable for its entire freedom from rusting or caking. The results which I have witnessed lead me to form a favorable opinion of it, both for precipitating sewage and for the further purpose of filtering effluent sewage either from tanks or from sewage farms, when the purification has not reached the required standard.

"Another precipitation system, called the 'Amines' process, has recently attracted attention. The materials employed are certain organic bases, which are found in the chemical group of amines (ammonia compounds) in combination with lime. The effect which is claimed for this is, that the sewage effluent from the process is