aged, more sewage is applied than can be purified by the surface-flow, even when that takes place through thick vegetation (as in the case of the samples from the fields of Italian rye-grass on the northern farm), and much more than can be purified under less advantageous conditions (as in the case of the samples from the field of mangolds on the southern farm, although the water from this field was mixed with that from two of meadow-land); and they show, too, that the valuable matters that are not utilized are not only thrown away, but are thrown away in their crude condition, not having been subjected to the oxidizing action necessary to convert them into innocuous nitrates and nitrites.

Lastly, we must notice the fact that the temperature of the effluent water of the northern farm is only slightly (less than one degree Fahr.) below that of the sewage, while the effluent water of the southern farm is actually half a degree Fahr. warmer than the sewage. This clearly shows that the sewage has not been subjected to the cooling which percolation through soil entails.

(6) Observations on the Sewage-Farm at Earlswood designed for the

Utilization of the Sewage of Red Hill and Reigate. This sewage-farm consists of about 70 acres of Earlswood Common, of which, it was stated, about 50 acres abutting on a tributary of the river Mole have been laid out for irrigation. It is intended very shortly to add more land to that already prepared from properties adjacent.

The soil is for the most part a clayey loam. The higher ground next the Common is rather freer in character, while the lower part appears to increase in density as it nears the outfall.

The surface, which has rather a steep fall in its higher part, gradually becomes more level as it descends, and has a very slight fall indeed as it approaches the outfall.

Before the sewage is delivered to the land for irrigation it passes through one of Latham's patent extractors, an ingenious invention for the separation of the solid from the liquid parts. The liquid sewage is delivered from the extractor by covered conduits, from which it is directed right and left into the highest carrier. The land laid out for irrigation is divided into three series of beds or slopes separated by roadways, on the upper side of each of which is a surface-drain to receive the effluent liquid as it passes off the beds above, and on the lower a main carrier to deliver the sewage for distribution to the series of beds below. The three series are divided rectangularly into nearly equal-sized blocks, to be again subdivided by minor or inner carriers, laid out partly on the catchwater and partly on the ridge-and-furrow form. The surface of the highest land of the uppermost series of beds is about 24 feet above the surface of the lowest land in proximity to the outfall-stream.

None of the land is underdrained, and the lowerniost beds appear to be incapable of underdrainage at a sufficient depth unless the stream receiving the water to be discharged is appropriately deepened at very considerable cost.

In answer to inquiries, it was stated that after heavy rains the lowest portions of the irrigated lands are swamped by the backing of the water which collects on their surface when the soil itself is in a state of complete saturation. At the time of the inspection by the Committee (July 11th), the sewage had collected in pools on the surface of the irrigated beds in a manner injurious to the crop under treatment. The work of irrigation is designed so that the sewage applied to the higher land may be reapplied on the sur

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face of lower lands with a view to its further purification. The sewage as it passed off the first surface was observed to be far from clear to the eye, and it was not perfectly so when leaving the second surface. When it was ultimately discharged at the outfall it was still cloudy, but this was partly accounted for by the heavy rains of the previous day. The analyses of samples of effluent water taken at different points, hereafter referred to, will show the extent of purification effected.

Though the land had not been drained, it gave indications of a natural capability of drainage in the escape of the sewage from the sides of the carriers or drains, which are from 10 to 14 inches deep. The line of saturation was clearly shown in those shallow cuts to be nearly identical with their depth, and the liquid was seen oozing out of the land at some parts in a clarified condition, and at others accompanied by a slimy matter, some specimens of which have been microscopically examined by Mr. M. C. Cooke, M.A., whose report is here given.

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Microscopical Examination of Slime and Mud from Bottom and Sides of

Carriers at Earlswood Farm. The fluid specimen of deposit sent to me for microscopical examination was the only one in a fit condition to report upon as to "the insects and animalculæ to be found therein.". Obviously dried mud would give no satisfactory result as to living animals, since the majority of them would be dead and shrivelled beyond all power of determination.

I have examined the wet deposit by the aid of the microscope, and find it to contain a few Diatoms belonging to several genera and species, but in a comparatively small proportion to the volume of material. The Desmidiaceæ were also represented by a species of Closterium, of which I detected but a few individuals. Confervoid threads were also but sparingly scattered through the mass. Altogether there was a smaller percentage of unicellular Algæ than I expected to have found. Living vegetable matter was comparatively rare.

The animal inhabitants of the mud were numerous, especially of certain kinds. There were a few examples of that common Thysanurous insect, Achorutes aqueticus, sometimes so plentiful in the liquid draining from heaps of manure.

The larvæ and pupæ of small Diptera I am unable to name in those stages, but their proportion was not large. Of Euglena viridis there was no lack; and any stagnant puddle, especially in the neighbourhood of farmyards, would have yielded an equal proportion. Infusorians were scarce; a few solitary individuals of Vorticella microstoma, and one or two specimens of Paramecium, were about all that I observed. But there was one group of animal organisms most abundantly represented, and these were the Annelids. When the mud was exposed to the light and sun, the surface became active with these creatures; about the diameter of a piece of cotton-thread, and from half an inch or less to nearly 2 inches in length, they wriggled over the whole surface. Some white, others pink, and a few of a deep blood-red were mingled together like eels, wriggling and scriggling in every drop that could be taken up and placed on a slide for examination. Skins without inhabitants were almost as plentiful; and it seemed to be impossible to get a drop of the material in the field of the microscope without either the worms themselves or empty skins.

(Signed) M. C. COOKE, M.A. It

appears to the Committee that the existence of the exuded matter described by Mr Cooke is mainly, if not wholly, due to the fact that the subsoil is kept in a saturated condition by the want of underdraining; and they desire to add their belief that with land thus saturated with sewage certain atmospheric conditions exist which may be attended by malaria more or less injurious to health. It need hardly be said that if the effluent liquid passing from a sewage-farm at a time when vegetation is in a luxuriant state, and when evaporation is more than ordinarily active (which was the case when

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the Committee viewed the land), is not clear to the eye nor sufficiently pure to be admitted into rivers, there must be times when it may

become exceedingly objectionable.

It is to be remarked in this case, moreover, that there was (on July 15th, 1871) more liquid passing off the land at the outfall than there was sewage delivered to it for application, due possibly to the passage of the recent rainfall through the porous soil of the higher part of the farm. This fact would, in the absence of the analyses of Dr. Russell, have led to the conclusion that the effluent liquid was purer than usual.

Observations on the Analyses of Sewage and Efluent Water from the

Red Hill and Reigate Sewage-Farm.
In 100,000 parts. Samples taken 14th and 15th July, 1871, in the pro-

portion of Tudo part of the flow.

Sewage at the

point where
it enters the
extractor.
Average flow 34:60 18:00 6.40
130 gallons
per minute
(tempera-

ture 38° F.) Sevage after

passing
through the
extractor
and before 33-00 17:50 4:16
application
to land
(tempera-

ture 58° F.) Efluent water

taken in
twelve por-
tions every
two hours,
after it had 1:29:10 17.80
passed over
one field of
rye-grass
(tempera-
ture 620-5 F.
Effluent water)

taken in ten
portions at
the outfall,
after it had
passed over
iwo fields of 35-80 24:20
rye-grass.
Average flow
152 gallons
per minute
(tempera-
ture 63° F.)

......
......

This is decidedly a weak sewage, as it does not contain one third of the quantity of “ actual” ammonia, nor one fourth of that of " albuminoid” ammonia that the samples of Tunbridge Wells (North Farm) contain ; the

a

smaller amount of chlorine also shows this. The fact is, that a very large quantity of subsoil water is admitted into the sewers.

The effect of the “extractor” is to reduce the total suspended matters by slightly more than one third of their amount, the amount of solid matter in solution is slightly lessened, and a quarter of the nitrogenous organic matters in suspension pass into solution; these are effects not in any way due to the action of the machine except as an agitator.

The effect on this sewage of a flow over one field of rye-grass, as shown by the analysis of an average sample made by mixing twelve samples in the proportions indicated by the amount of flow at the time of collecting, was as follows:

The suspended matters, being very small in amount, were not determined. The solid matters in solution were reduced in total amount, the reduction being chiefly due, as in the case of the Tunbridge-Wells farms, to the retention by the soil and plants of the more volatile substances, as the amount of solid matters left after ignition is practically the same in the effluent water as in the sewage. The lessening of the chlorine by more than one fourth of its original amount would point to the fact, already referred to, that a considerable amount of subsoil water dilutes the effluent water; but notwithstanding this dilution, the effluent water contains more than half as much “ actual” ammonia as the same bulk of sewage (after passing through the extractor), and a quarter as much “ albuminoid” ammonia, while the amount of nitrogen escaping as nitrates and nitrites is insignificant.

This effluent water is therefore not purified in a satisfactory way at all.

But the most interesting point about these analyses is the comparison of the effluent water which had passed over two fields of rye-grass with that which had only passed over one.

On a primă facie view, it would have been expected that the former would have been much purer than the latter; but in this case, on the contrary, we find that the effluent water which has passed over two fields contains, in the same bulk,

1. More than one fifth more solid matter in solution,
2. More than one third more fixed solids,
3. More “ albuminoid” ammonia, viz. 0·10 instead of 0·06,
4. Rather more chlorine,
5. Very slightly less nitrogen as nitrates &c.,

6. More than one fourth less “ actual” ammonia, than the effluent water which had passed over one field of rye-grass.

This shows us :

1. That by passing over an additional field, the sewage has been strengthened instead of weakened, except as regards “ actual” ammonia.

(That this strengthening is probably due chiefly to evaporation through the agency of the plants, is shown by the increase in albuminoid ammonia, and by the fact that the actual ammonia is the only constituent lessened in amount to any extent.)

2. That the nitrogenous organic matters, as shown by the amount of albuminoid ammonia, are increased.

3. That no additional oxidizing action took place. These results are what might have been anticipated from the description of the farm already given.

The soil, not being underdrained, is saturated with sewage, and the effluent water flowing off one field on to another, already saturated with sewage, can only concentrate itself by evaporation or by solution of matters in the upper layer of the soil.

There is this, then, against the catchwater-system, that if the fields are not underdrained the land will become saturated with sewage, and the effluent water will then pass off in an impure condition; and not only so, but the present example shows that after a second application the water may (except as regards actual ammonia) contain a greater amount of soluble impurities than it did before; and, above all, the nitrogenous organic matter (as indicated by the albumenoid ammonia) is not diminished, but rather increased, in spite of the active growth going on in the month of July.

The temperature of the effluent water from the first field was considerably (+ Fahr.) higher than that of the sewage, and that from the second field half a degree higher than that from the first, a sufficient proof that percolation through the soil does not take place.

It may seem almost superfluous for the Committee, after so many years of general experience throughout the country, to argue in favour of the subsoil drainage of naturally heavy or naturally wet land with impervious subsoil for the purposes of ordinary agriculture; but some persons have strongly and repeatedly called in question the necessity of draining land when irrigated with sewage ; and the two farms at Tunbridge Wells, to a great extent, and more especially the Reigate Farm at Earlswood, have been actually laid out for sewage-irrigation on what may be called the saturation" principle ; so that it appears to the Committee desirable to call attention to the fact, that if drainage is necessary where no water is artificially supplied to the soil, it cannot be less necessary after an addition to the rainfall of 100 or 200 per cent. But a comparison of the analyses of different samples of effluent waters which have been taken by the Committee from open ditches into which effluent water was overflowing off saturated land, and from subsoil-drains into which effluent water was intermittently percolating through several feet of soil, suggests grave doubts whether effuent water ought ever to be permitted to escape before it has percolated through the soil,

SECTION IV.-The Phosphate Process. A Member of the Committee was present at an experiment which was performed with the phosphate process of Messrs. Forbes and Price at Tottenham on March 25th, 1871. His description of the experiment is as follows:

The Tottenham sewage, after passing through some depositing tanks which had been constructed for the lime-process, was pumped up, at the rate of about 800 or 1000 gallons per minute (as stated), along a carrier into a tank 100 yards long and of gradually increasing breadth. This tank took three hours to fill.

As tho sewage passed along the above mentioned carrier, the chemicals were mixed with it in the following way :

Two boxes were placed over the carrier, one a few yards further along it than the other; the first contained the phosphate mixture, and the second milk of lime. Men were continually stirring the contents of each box, which were allowed to run continuously into the sewage as it passed underneath the boxes.

The phosphate mixture was stated to be made by powdering the native phosphate of alumina, mixing it with sulphuric acid in the proportion of a ton of phosphate to from 12 to 13 cwt. of the acid, and dissolving the mass in water.