passes from the land pretty satisfactorily purified. It is estimated that, after making deduction of £4 for rental, the gross return per ton of sewage applied is, at the present prices of the produce, with Italian rye-grass from d. to 1d., and with meadow grass from d. to 3d. The sewage is not applied in any systematic manner to other crops, but it has been tried on a small scale to root-crops. An enlargement of the area of irrigation is contemplated, which will, if carried out, somewhat reduce the amount of fluid and excretal matters available per acre below the quantities above stated.

About 12 years ago, arrangements were made for collecting the sewage of Rugby in a tank, from which it is pumped, by a 12-horse power engine, through iron pipes laid down for the distribution over about 470 acres of mixed arable and grass land. Up to last year 190 acres were held by Mr. James Archibald Campbell, but he has gradually limited the area of application, and during the last few years has abandoned the use of hose and jet, excepting occasionally on a small scale, and confined the application almost exclusively to from 12 to 20 acres of meadow and Italian ryegrass. The remainder of the land, amounting to about 280 acres, has passed through the hands of two tenants, both of whom are said to have sustained considerable loss. The last of the two had confined the application almost exclusively to about 100 acres of grass land, and applied the sewage almost entirely by open runs. The whole is now in the hands of the landlord, Mr. G. H. Walker, who, it is understood, is contemplating the abandonment of the use of steam power, pipes, and hose and jet, and the application to a limited area by means of gravitation.

The general result at Rugby is, then, that after about a dozen years of practical experience, with arrangements adapted for the application of small quantities of sewage per acre, to arable as well as to grass land, and to all crops, the area has been greatly limited, the use to any other crops than meadow and Italian ryegrass is quite exceptional, and the application by means of steampower, pipes, and hose and jet, will probably soon be entirely abandoned. It may be added that, at the time of the experiments of the Commission, the sewage, which was considerably stronger than that of the Metropolis, cost the tenants only about ad. per ton at the hydrants in the fields; yet, rather than incur the loss of using it at that cost, both were glad to get rid of it to the Commission, at rates which, though three times as high during the

six summer as during the six winter months, averaged the year round scarcely, but very nearly, 1d. per ton at the hydrants.

Some years ago, the Earl of Essex laid down pipes for the application of the sewage of Watford, by pumping and hose and jet, to about 210 acres of mixed arable and grass land. The results which his Lordship obtained on the application of only 134 tons of sewage per acre to wheat have frequently been held to be conclusive proof of its applicability in small quantities per acre over large areas, to arable land, and to all crops. But in the evidence given by his Lordship before the Sewage Committee of 1862, he stated, very emphatically, that his great error had been the piping of too much land; that he required 5,000 tons per acre for 10 acres of rye-grass; and that, applying the remainder to 35 acres of meadow, he had none to spare for wheat. In other words, although the abandonment of one acre of rye-grass would set free sewage enough for nearly 40 acres of wheat, if applied only at the rate which yielded the large gross return per ton of sewage so frequently quoted, yet his Lordship's practical experience had led him to prefer the application to the one acre of rye-grass rather than to the nearly 40 acres of wheat. Further, his Lordship gave it as his opinion that sewage would not be profitable to the farmer unless he could have it at from d. to d. per ton.

Referring to the question of the application of sewage to corn crops, it may be stated that, in an experiment made by the Commission at Rugby, with oats, a very high gross money return per ton of sewage was also obtained. The experiment was made in the unusually productive season of 1863, and with sewage of about double the average strength of that of the Metropolis, applied during a period of very dry weather. The results were, therefore, quite exceptional, and cannot be taken as affording any indication of what might be expected from the application of small quantities of sewage to corn crops generally, on different soils, and on the average of seasons. There cannot, indeed, be a doubt, that to obtain a maximum gross value of produce from a given amount of sewage, it should be applied in small quantities per acre, and in dry weather. But sewage is produced in large daily amount at all seasons, and must be disposed of as soon as it is produced. It must, therefore, be applied in winter, when of comparatively little value, as well as in summer, when of more, and it would frequently be quite inapplicable to arable land. Moreover, to obtain an increased gross money return per ton of sewage by using it on a

comprehensive scale for corn and other ordinary rotation crops, would involve the extra cost of main distribution over at least a ten-fold, if not frequently a twenty-fold area, and require the application to a great extent by the expensive means of pipes and hose and jet, instead of by the economical one of open runs.

At Malvern and Tavistock the application of sewage to grass land has now been carried on for some years, but at Worthing it has only very recently been commenced.

From this short review of the experience of practical men who have undertaken the utilization of sewage with a view to profit, it appears that, wherever arrangements have been made for the application of small quantities over large areas, to corn and other rotation crops on arable land, and by means of pipes and hose and jet, the undertaking has either been entirely abandoned, or the area greatly limited, and the application confined almost exclusively to meadow and Italian rye-grass. On the other hand, the undertakings which have been the most successful from the agricultural point of view are those in which the arrangements have been adapted for the almost exclusive application to grass, and the application to other crops is only exceptional.

The practical conclusions deducible from the whole inquiry may be briefly stated as follows:

1. It is only by a liberal use of water that the refuse matters of large populations can be removed from their dwellings without nuisance and injury to health.

2. That the discharge of town sewage into rivers renders them unfit as a water supply to other towns, is destructive of their fish, causes deposits which injure their channels, gives rise to emanations which are injurious to health, is a great waste of manurial matter, and should not be permitted.

3. That the proper mode of both utilizing and purifying sewage is to apply it to land.

4. That, considering the great dilution of town sewage, its constant daily supply at all seasons, its greater amount in wet weather when the land can least bear, or least requires more water, and the cost of distribution, it is best fitted for application to grass, which alone can receive it the year round. It may, however, be occasionally applied with advantage to other crops within easy reach of the line or area laid down for the continuous application to grass.

5. That, having regard both to urban and rural interests, an application of about 5,000 tons of sewage per acre per annum, to meadow or Italian rye-grass, would probably, in the majority of cases, prove to be the most profitable mode of utilization, though the quantity would have to be reduced, provided experience showed that the water was not sufficiently purified; and it is pretty certain that the farmer would not pay d., and it is even very doubtful whether he could afford to pay d. per ton, the year round, for sewage of the average strength of that of the Metropolis (excluding stormwater) delivered on his land.

6. That the direct result of the general application of town sewage to grass land would be an enormous increase in the production of milk, butter, cheese, and meat; whilst, by the consumption of the grass, a large amount of solid manure, applicable to arable land and to crops generally, would be produced.

7. That the cost or profit to a town of arrangements for the removal and utilization of its sewage must vary very greatly, according to its position, and to the character and levels of the land to be irrigated. Where the sewage can be conveyed by gravitation, and a sufficient tract of suitable land is available, the town may realize a profit; but, under contrary conditions, it may have to submit to a pecuniary sacrifice to secure the necessary sanitary advantages.

XII.-On a New Method of Forming Organo-metallic Bodies. By J. ALFRED WANKLYN, Professor of Chemistry at the London Institution.

EIGHT years ago I showed that sodium attacks zinc-ethyl, precipitating zinc, and forming sodium-ethyl. Having observed similar reactions between zinc-ethyl and the metals potassium, lithium, calcium, and strontium, and having regard to the great facility with which these displacements of metal are effected, I was led to compare them to the well-known electro-chemical precipitation from ordinary metallic solutions, and to regard them as examples of a very general method of producing a number of the organometallic bodies.

On the present occasion I have to announce a different method of procedure. Instead of taking an organo-metallic compound of

a less positive metal and attacking it with a more positive metal, I take an organo-metallic compound of one of the most positive metals and attack it with mercury, or with an amalgam, or a mixture of mercury with some other metal. The result of the operation is an amalgam of mercury with the positive metal, whilst the organic radical unites either with the mercury or with the other metal.

Thus the new method of forming organo-metallic bodies consists in utilizing for that purpose the great affinity of mercury for the alkali-metals. The following examples will serve to characterize it :

Mercury, Zinc and Sodium-ethyl.

When the crystalline compound of sodium-ethyl and zinc-ethyl,* which is prepared by treating zinc-ethyl with sodium, is heated in the water-bath with mercury and zinc, it is rapidly resolved into zinc-ethyl and sodium-amalgam, according to the following equation :

Hg + Zn + 2NaC2H ̧

=

HgNa2+ Zn(C2H5)2.

In one experiment, I took about 10 grms. of the compound containing sodium-ethyl, and sealed it up with mercury and zinc, and heated in the water-bath. The result was a quantity of pretty pure zinc-ethyl, not less than 7 grms., and an amalgam of sodium. very rich in sodium. I made an analysis of a portion of the 7 grms. of zinc-ethyl. It did not contain so much as 0.5 per cent. of sodium.

Mercury, Magnesium, and Sodium-ethyl.

Some of the crystals containing sodium-ethyl were sealed up with mercury and magnesium-wire. After a short heating in the water-bath they did not form a liquid as in the last case, but a white solid. On opening the tube it was observed that the mercury was very considerably alloyed with sodium, and that the white solid, which did not fume, took fire spontaneously in the air, and contained magnesium and zinc, but not more than traces of sodium. Evidently, therefore, the reaction was essentially—

* Ann. Ch. Pharm. (1858).

+ The mercury effervesced furiously with water, much more violently than a simple amalgam of sodium does. It would seem that the presence of a little metallic magnesium in sodium-amalgam heightens the activity of the amalgam.