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Having disposed of the mineral solid refuse, let me invite your attention to the vegetable solid refuse. This consists of garbage, part of which is brought with the ashes, and part is found in the pails. It includes the sweepings of the markets, also straw, shavings, rags, sacks, and an endless assortment of minor articles. To destroy absolutely these things would be wasteful, as they constitute the raw materials out of which is made one of the most valuable substances for a sanitary committee. I allude to charcoal. A portion of the cinders before referred to as food for the Destructor presents the needful fuel. All that is required is a form of apparatus that shall, without much labour and without producing any offensive odour, convert the garbage into charcoal.

The patent Carboniser effects this object. It consists of a rectangular chamber of considerable height, into the top of which the material to be operated upon is thrown, and through which chamber it gradually descends as its bulk diminishes, and as the material below is removed. Finally, when sufficiently carbonised, it is withdrawn through a slide in the bottom of the chamber. This chamber is heated by a furnace placed at the side. The fire in the furnace is kept thick, and the supply of air to it small, so as to prevent the admission of sufficient oxygen for perfect combustion. Thus the products of combustion from it can only heat, and not remove the carbon, and they may therefore safely be brought into direct contact with the materials to be carbonised. These products of combustion enter the kiln, or carbonising chamber, near the bottom, and are guided around it by iron plates which touch the

wall at their top edges, but slope so that their bottom edges are some distance from it. These are ranged round the chamber in a spiral form, and keep open a passage along which the products of combustion can always find a way to the chimney, while being open at the bottom, the gases can come into direct contact with the materials in the kiln. The plates becoming heated, also help to dry and carbonise the materials. Finally, the products of combustion are led away to the chimney through a flue near the top of the chamber.

Condemned food, stale fruit, and vegetables are readily disposed of by the Carboniser. Sweepings of paved streets contain much vegetable matter, portions of hay and straw, horse droppings, &c. These are readily carbonised, and the charcoal thus produced, as well as that from the more exclusively vegetable matter before adverted to, is most valuable.

First, as a DEODORANT. A small portion scattered over the most offensive materials actually destroys all trace of odour. Its effect is almost magical. Where the pail system is used, a very small portion of charcoal discharged automatically, as in Moser's closets, or dusted over the contents, effectually destroys odour. Even if a bag of charcoal be emptied in a foul atmosphere, such as a place where nightsoil is mixed, the fine particles of charcoal floating in the air render it perfectly sweet. Charcoal is a needful commodity where the pail system is used.

Second, as a DISINFECTANT. Mixed with a small proportion of crude carbolic acid, the charcoal may be presumed to be one of the most valuable and effective disinfectants known. The charcoal is well known to

abolish offensive organic matters, and to destroy them by a peculiar power which it has of causing oxidation, but it cannot enter the atmosphere (except in the condition of dust). This permeation of the air is effected by the carbolic acid, and the combination is found to be very valuable. The Health Committee of Manchester make free use of this carbolized charcoal with excellent results.

The advantage to be derived from placing a layer of charcoal over every coffin before closing a grave has been often pointed out, but the difficulty of obtaining at a moderate cost and in sufficient quantity a material that would ensure the salubrity of graveyards and cemeteries, and that would prevent the offensive effluvium that sometimes emanates from re-opened graves, has prevented its use. Now that it is easy to secure an abundant supply at a trifling cost, this needful sanitary reform may be accomplished. Cremation of the vegetable refuse will not present the difficulties attendant on the cremation of the human body, yet it will secure some of the advantages sought.

Third, as a DECOLORANT. A portion of the contents of one of the Manchester sewers, mingled with water from the river Medlock, and fortified with the contents of two inkstands, one containing writing and the other copying ink, and these further coloured by an infusion of logwood and a solution of indigo, made a fluid that was opaque in a half-inch test tube, and that would serve as writing ink. Passed through a filter composed of a small quantity of carbonized garbage, this filthy and black mixture became in appearance identical with spring water.

Street sweeping ground with a portion of clay, and carbonized, produce a filtering medium of great power, and so little friable in its nature as to make an excellent filter bed and one which is in use at the present time by various dyers. This material forms the subject of one of the patents held by the Universal Sewage Company.

Fourth, as an OXIDIZER. A portion of the Birmingham sewage was subjected to filtration through a bed of charcoal produced by the carbonization of sewage sludge. It became brilliant in appearance, and when subjected to analysis by order of the Mayor, it was found to contain far less ammonia and organic nitrogen than sewage which had passed through the land as a filtering bed. This promising mode of treating sewage with the charcoal derived from sewage sludge is too recent a discovery to have been practically applied.

The Carbonizer, like the Destructor, is composed of a series of cells, each of which can deal with 50 cwts. of garbage per day.

You have now been so good as to traverse with me the first of the three divisions of our subject, namely, the mode of dealing with the solid refuse, which we have converted into mortar and charcoal.

We will now consider the second division, namely, those portions of the refuse of towns that must be removed by the sewers. These may be conveniently grouped under three heads :

(a.) The involuntary supply to the sewers.

(b.) The voluntary supply from dwelling-houses. (c.) The voluntary supply from other sources.

(a.) The involuntary supply consists of rain water that finds its way into the sewers; of natural springs; and of leakage from the general water supply. These are the natural feeders of rivers; the former two would exist if the towns were absent, and the last is no source of contamination. So far then as these are concerned, there is little that even the fastidious may complain of.

(b.) The voluntary supply from domestic sources consists of water used for washing and culinary purposes. As the impurities from these sources consist mainly of soap and fat and very little nitrogenous matter, it is evident that were the contents of sewers confined to these substances, a very moderate treatment would suffice to render the water fitted to enter streams.

(c.) The voluntary supply from other sources includes the fluids discharged from mills and manufactories, also the discoloured water returned by dyers and bleachers. Some small portion of these liquids is too foul to warrant its being turned direct into rivers, but a larger portion, which is merely dye water, can be readily deprived of its colour, as before shown; and the remainder, which consists of water from mills, is practically free from contamination, having been simply used for condensing the steam which drives the engines.

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Thus it appears that those liquids, which must of necessity find their way into sewers, do little to pollute them, and may be rendered comparatively pure by a moderate treatment.

We are now only left to consider the last of the three divisions into which we classed the refuse of

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