and zinc) sufficiently large to cause vomiting with its attendant depression. The illness only occurs in those who are new to the work, or who resume work after an absence of a month or even a fortnight, and there are no hot or sweating stages as in true ague. The men who suffer in this way drink freely of milk and promote vomiting, the best treatment that could be devised for copper or zinc poisoning. Chronic copper poisoning is common amongst brass-workers, and bronchitis from inhalation of irritant dust. In the manufacture of bichromate of potash a dust is inhaled which causes nasal ulceration. Match makers, before the introduction of red or amorphous phosphorus, used to suffer from necrosis of the jaw, the result of exposure to phosphorus fumes; and silverers and gilders, who worked with amalgams of gold and silver with mercury, were formerly the subjects of mercurial poisoning, until electro-plating by electrolysis replaced the old methods.

Two other occupations may be mentioned, in which the workers are exposed to carbonic acid gas inhalation. These are well-sinkers, who are occasionally asphyxiated by the large amount of this gas which is evolved from the soil, and collects in deep shafts; and sodawater manufacturers. In this latter occupation, however, the CO, is never present in the air in sufficient quantity to cause injury to health or life.

The offensive trades mentioned in the Public Health Act of 1875 are those of blood-boiler, bone-boiler, fellmonger, soap-boiler, tallow-melter, tripe-boiler. The model bye-laws of the Local Government Board include in addition those of blood-dryer, leather-dresser, tanner, fat-melter or fat-extractor, glue-maker, size-maker, and gut-scraper, as being trades for which regulation by sanitary authorities is desirable.

These regulations have for their object (1) the keeping of offensive stores in proper receptacles, so as to prevent the emission of noxious effluvia; (2) the daily removal of offensive waste materials, or their storage, when they must remain on the premises, in properly covered vessels or receptacles, to prevent nuisance; (3) the regular cleansing of the premises, and the enforcement of adequate ventilation, water supply, and drainage; (4) the discharge of all vapours and gases, produced in the course of manufacture, at such a height into the air as to render the noxious effluvia not injurious to the neighbourhood; or in certain cases the gases must be passed through the furnace and destroyed before discharge. In other cases the gases must first be passed through a condensing apparatus, to condense steam or other vapours by a low temperature; or by passage of the gases through water or over certain chemicals, solution or absorption of the noxious vapours may be attained.❤

The Local Government Board has also issued model bye-laws for the regulation of slaughter-houses, and for the prevention of the keeping of animals on any premises so as to be injurious to health.

The Alkali Works, etc., Regulation Act of 1881, provides that 95 per cent. of the hydrochloric acid gases and vapours produced in alkali works must be condensed; and in each cubic foot of air, gas, or smoke escaping into the atmosphere there may be only grain of HCl. Each cubic foot of air, gas, or smoke, issuing from sulphuric acid works must not contain more than 4 grains of sulphuric acid (SO3). The keeping apart of acid drainage and alkali waste is strictly enforced; and all waste substances must be got rid of without nuisance. Other works included in this Act are salt

* See Dr. Ballard's Report on Effluvium Nuisances.

works, cement works, chemical manure works, nitric acid works, sulphate and chloride of ammonia works, chlorine works, bleaching works, and gas liquor works.

Nuisance may also result in the neighbourhood of gas works by the accumulation of deposits of lime, removed from the chambers where the ammonia and sulphur compounds are absorbed from the coal-gas.

Household Dust.

Besides vitiation by products of respiration and combustion, one great cause of impurity of air in houses is the presence of floating particles of dust. This dust is the débris arising from the wear and tear of articles in domestic use, mingled with the soot and ashes from fireplaces, lamps, and gas burners. As soon as the air is still, it tends to settle upon walls, floors, and articles of furniture, to be again caught up and wafted into the air, when this is in brisk movement. Under the microscope this dust resolves itself into soot, mineral particles (sand, crystals of sodium chloride), cotton fibres, spores of fungi or bacteria, starch grains, pulverized straw, epithelial and epidermic débris from the skin. It is thus seen to consist largely of organic refuse, often more or less putrescent, and its presence in the air assists in the production of the low state of health so common to the occupants of dirty, overcrowded houses.

In all houses dust must be produced by the wear and tear of domestic life; but in towns this strictly domestic dust is much augmented by that which finds its way in through doors and windows from the outer atmosphere. We cannot hope then to materially limit its production; but much may be done to get rid of it, and to prevent its

undue accumulation by thorough and regular housecleaning.

House-cleaning can only be efficient where the structural conditions of walls, floors, and ceilings, permit of easy access for the broom and duster into every part of the room, and where furniture and fittings are so arranged as to prevent dust being deposited in inaccessible places.

As generally arranged, nearly every part of a room is a dust-trap. Cornices and projections on ceilings and above doors; rough or flock wall-papers; floors with crevices between the boards into which dust drops, to gradually accumulate between the floor and the ceiling below; carpets accurately fitting every corner of the room; cumbersome articles of furniture as wardrobes, side-boards, and book-cases, which collect dust above, and are too heavy to be moved to allow dust to be swept out below; heavy curtains with canopies, draperies, etc.; all these tend to the collection or absorption of dust, which, being unseen, is forgotten and not removed.

It is especially in bed-rooms, which are occupied for so many hours without any thorough renewal of the air, that these dust absorbers and accumulators tend to do so much harm, by contaminating an atmosphere already sufficiently vitiated. The following rules therefore, although to be recommended in every room of a house, are more especially applicable to bed-rooms.

The floors, if old and warped, should be accurately fitted with thin oak parqueterie, kept well polished with oil and beeswax; or the spaces between the boards may be filled in with strips of wood, so as to leave no chinks, and the whole either stained and varnished, or coated with three or four good coats of paint, and varnished. This

flooring can be kept clean with a damp duster. Carpets should be abolished in favour of mats or Indian matting for bed-rooms, which is very non-absorbent and easily cleaned. The mats can be frequently shaken and beaten in the open air, whereas fixed carpets are usually beaten once a year, and in the interval accumulate (especially the thick pile carpets) every kind of refuse and abomination. The use of linoleum and oil-cloth should be avoided, as it hinders the ventilation of the boards, and tends to cause dry-rot.

Heavy curtains, canopies, and draperies should be replaced by light muslin fabrics-more especially in bedrooms-which can be washed and cleaned at frequent intervals. Bed-room furniture should be light and easily moved. It would be a great improvement, if, when houses were built, the bed-room walls were planned with recesses, which could be converted into cupboards, shelves, and drawers; and thus the actual furniture of a bed-room could be reduced to the bed, wash-stand, dressing-table, and chairs, and there would be no surface on which dust could lie concealed.

Cornices and projections from walls and ceilings should be avoided, as likely to collect dust.

The wall coverings should be smooth and glossy. Rough wall-papers, especially flock-paper, can hold enormous quantities of dust. For bed-rooms and nurseries, distemper colouring is perhaps better than wallpapers, as the surface can be renewed at trifling cost, and at frequent intervals. In distempering, common whiting is used as a basis for the colouring, and not white lead or zinc white, as is almost invariably the case in painting. Newly painted surfaces give off traces of lead, volatilised or in powder, to the air in drying; and symptoms of lead-poisoning are not uncommon in the