Read Ebook: Hygiene: a manual of personal and public health (New Edition) by Newsholme Arthur Sir

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The artificial character of town life is commonly adduced as an argument for the moderate use of alcohol. In the case of healthy workers, this does not hold good; many of our hardest workers and thinkers take no alcohol.

The universality of the habit of taking stimulants is a curious argument on the same side, though if the habit be bad, this can be no more reason for continuing it than can the prevalence of vice be an excuse for indulgence in it.

It has been already stated that a quantity of alcohol under 1 or 1 1/2 ounces may become oxidised in the system, and may thus form a source of heat. But in all probability, although it may be regarded as a food, it is a most inconvenient one, inasmuch as it diminishes the oxidation of other foods. It has been aptly compared in this respect to sulphur, which is an oxidisable material, but which, when it is burnt in a chimney, in which the soot is on fire, will put an end to the combustion of the latter. Its value as a food, under normal conditions, is practically nil.

The late Dr. Parkes, the greatest authority on the dietetic use of alcohol, has summarised the argument as to the dietetic use of alcohol as follows:--

"But what, now, should be the conclusion as to the use of alcohol in health after growth is completed? Admitting the impossibility of proving a small quantity to be hurtful, and at the same time acknowledging the dangers of excess, there arises an argument which seems to me somewhat in favour of total abstinence. No man can say when he has passed the boundary which divides safety from harm; he may call himself temperate, and yet may be daily taking a little more than his system can bear, and be gradually causing some tissue to undergo slow degeneration. He may be safe, but he may be on the verge of danger.

"This uncertainty, coupled with the difficulty at present of saying what dietetic advantage is gained by using alcohol, seems to me rather to turn the scale in favour of total abstinence instead of moderate drinking. But if any one honestly tries, and finds he is better in health for a little alcohol, let him take it, but he should keep within the boundary line, viz., that 1 1/2 ounces of pure or absolute alcohol in twenty-four hours form the limit of moderation. I do not then think he can do himself any harm."

The difference in colour between red and white wines is produced by allowing the juice in the former to ferment in contact with the skins, from which the colouring matter is extracted by the alcohol. Both red and white wines may be obtained from either red or white grapes. From the skins also are extracted a salt of iron, and a peculiar form of tannin. Tartaric and acetic acids, and tartrate of potass, are present in varying quantities in wines; in old wines the tartrate separates as bitartrate of potass, forming with tannin and colouring matter the "crust" of port and other wines. The "bouquet" of wines is due chiefly to certain volatile bodies, such as pelargonic ether. The proportion of alcohol in wines varies from 6 to 14 per cent. As fermentation is stopped by the presence of 14 per cent. of alcohol, any larger amount of alcohol than this must have been added to the wine.

Wine, like beer, has a strong tendency to produce gout, especially the sweet and strong wines. It has not, however, the same tendency to induce obesity.

Prolonged indulgence in spirits produces the various organic diseases already described, and unless well diluted they are more harmful than beers or wines. They differ from wines and beers in not tending to produce gout, and from beer in not leading to obesity.

WATER.

In hot summer weather the consumption is about 20 per cent. above the average of the year; and frost often increases the amount 30--40 per cent. above the average, owing to the bursting of pipes, or the loss from taps foolishly left open to prevent bursting.

Water companies usually reckon 30-60 gallons for each individual, to allow for the water required for scavenging and manufactories and for waste. In large houses and hotels where baths are freely used, often as much as 70 gallons per head is used, and in hospitals the amount averages from 60 to 90 gallons per head. The following is Parkes' estimate of the daily allowance for all purposes:--

It has been proposed to put a water-meter to each house, so that the rate may be in proportion to the amount of water used. The plan is objectionable for two reasons: 1st--Because it tends to restrict the necessary use of water for purposes of cleanliness. A scant supply of water is always followed by uncleanliness of house and person, with its consequent diseases; at the same time closets may be imperfectly flushed, and may become choked. 2nd--Because of the primary expense of the meter, and of its maintenance.

SOURCES OF WATER SUPPLY.--All our drinking water is obtained in the first instance, by a natural process of distillation on a large scale. The sun is constantly causing evaporation from sea and land. The vapour produced, being condensed by a lower temperature, returns to the earth as snow, dew or rain. All these natural products have been at times utilised as sources of drinking water.

The Rivers Pollution Commissioners found that out of eight samples of stored rain-water only one was fit to drink. They came to the conclusion that rain-water, collected from the roofs of houses and stored in underground tanks, is "often polluted to a dangerous extent by excrementitious matters, and is rarely of sufficiently good quality to be used for domestic purposes with safety." Also, that in Great Britain, and more particularly in England, we shall "look in vain to the atmosphere for a supply of water pure enough for dietetic purposes."

The use of rain-water for drinking purposes is only justified in isolated country houses where no better source is available; and under these circumstances the greatest care should be taken to prevent contamination with lead or organic impurities.

The amount of water falling on any impervious material obtainable from rain can easily be estimated, if the amount of rainfall and the area of the receiving surface are known. The average annual rainfall in this country is 33 inches .

We may assume the amount practically available to be 20 inches per annum, and the area of the receiving surface 500 square feet. Multiply the area by 144, to bring it into square inches, and this by the rainfall, and the product gives the number of cubic inches of rain which fall on the receiving area in a year. One cubic foot, or 1,728 cubic inches, of water being equivalent to 6?23 gallons, the number of gallons of water can be easily calculated. To calculate the receiving surface of the roof of a house, do not take into account the slope of the roof, but merely ascertain the area of the flat space actually covered by the roof. This may be done roughly by calculating the area of all the rooms on the ground floor, and allowing an additional amount for the space occupied by the walls. It has been estimated that, even if a rain-water supply for towns were desirable, the amount collected from the roofs of houses would scarcely average two gallons per person daily--assuming the average rainfall to be 20 inches, and that there was a roof area of 60 square feet for each individual.

The amount practically available from rain falling on different soils varies with their porosity and slope. Thus, according to Professor Rankine, the proportion of the total rainfall available is as follows:--

Nearly the whole on steep surfaces of granite, gneiss, and slate;

From three to four-fifths on moorland hilly pastures;

From two-fifths to half on flat cultivated country; and

None on chalk.

In the utilization of upland surface water the water from the surrounding hills is collected at the bottom of a valley, in an artificial, strongly-constructed lake; or in a natural lake, as in Loch Katrine .

Upland surface water is nearly always soft. Its use is much more economical than that of hard water. It may be brownish, from the presence of peat, but this is not objectionable, so far as health is concerned. Its occasionally solvent action on lead is a more serious objection. The population of many parts of Yorkshire and Lancashire have suffered severely from chronic lead poisoning, due to the action of certain upland surface water on lead service pipes. Only the waters giving an acid reaction possess this plumbo-solvent power.

In the land spring water crops out at the point where the porous stratum ceases. Deep springs may crop out in the same way as land springs, except that they appear at the bottom of deeper strata. Or they may be formed by faults. Both these are shown in water having percolated through the chalk beneath the superficial clay, is stopped at the "fault" by the lack of continuity of the chalk stratum, and is consequently confined under pressure. It therefore makes its way to the surface, forming a spring. In its passage underground, water , is able to dissolve small quantities of chalk, sulphate of lime and of magnesium, and traces of oxide of iron, aluminium oxide, and silica. Spring-water possesses an equable temperature, generally about 50? Fahr., while impounded or river water is always warm in summer and cold in winter. Spring water is well-aerated, while river water, and still more rain-water, are flat.

Among the deepest Artesian wells are Grenelle , and Kissingen The sinking of a deep well and severe pumping of its water may exhaust all the neighbouring wells for two or three miles. There is also danger of contamination from neighbouring cesspools when the upper part of the deep well is not properly constructed. The area exhausted by a deep well undergoing pumping is represented by an inverted cone, having a very wide base, and with a convex inner surface pointing towards the well.

For country places deep-well water is much preferable to water from streams, as streams are very liable to be contaminated by the sewage of houses higher up in their course, or even by that of houses close by. A good well should be at least thirty feet deep--preferably fifty feet and should always be lined with impervious material, except near its bottom. The absolutely water-tight and impervious condition as well as the distance of all drains or cesspools in the vicinity should be ascertained before deciding whether the drinking water from a given well is above suspicion. The direction of flow of the underground water should also be determined. This may be done by measuring the level of all the wells in the neighbourhood. Possible sources of pollution at points from which ground water is flowing towards the well are much more dangerous than those nearer than the well to the river towards which the underground water is flowing . Steam pumping greatly increases the area from which contamination may be derived.

An excellent plan to obtain water for villages, in a gravelly soil, is to sink a Norton's Abyssinian tube well for fifty or sixty feet.

In towns it is preferable to trust to the public water supplied, rather than to any private well; and in villages, a general supply from a pure source should also be provided.

If no contamination be present in the water of a river, it forms a good source of water-supply; being running water, it is always fairly well a?rated, and is not usually so hard as spring-water.

Even if sewage has entered a river, it is asserted that it becomes a safe source of water-supply, after passage through filter beds, the sewage having been got rid of in four ways.

In regard to the comparative merits of the various waters described, it will be useful to give here the classification made by the Rivers Pollution Commissioners in their sixth report:--

Passage through certain geological strata has a great influence in rendering water palatable, colourless, and wholesome by percolation.

The following strata are said by the Commissioners to be the most efficient:-- Chalk, oolite, greensand, Hastings sand, new red and conglomerate sandstone. Fissures or cracks in these strata may cause the water to pass through them unpurified by filtration.

THE STORAGE AND DELIVERY OF WATER.

The methods of storing and delivering water will vary with its source. In rural districts, deep wells and springs are the best sources of supply; but in large towns they are found to be insufficient for the wants of a rapidly-increasing population; and they can only be multiplied in a given district within certain limits, as every well drains a large surrounding area. The supply from surface wells in gravel or sand beds or in chalk districts is liable to fail in seasons of drought; but deep wells in oolite or chalk formations, and in the new red sandstone, generally yield a constant and abundant supply.

Water collected near its actual place of fall, and from uncultivated districts, is always purer than that collected further from its source, and from cultivated land.

This must be high ground, above the level of the highest houses to which water has to be supplied, as water cannot rise above its own level. When this cannot be arranged, the water is pumped into tanks at a higher level, and distributed from them.

The greatest hourly demand for water being double the average hourly demand, the water-mains supplying a town must have double the discharging power that would be required, supposing the demand was uniform. The first requisite of a supply of water is that it should be abundant, and sufficient in amount for any extra strain on its capacities. Water ought to be laid on to every house, and to at least two floors of the house. Anything preventing free access to water, militates against cleanliness.

When the water-supply is from a river, filtering beds are needed, in addition to the parts of a water-service hitherto described. Moreover, since the river is usually at a low level, the water, after passing through the filtering beds, requires to be pumped into raised tanks, from which it is delivered.

In laying down water-pipes, in the streets and to houses, it is very important to make the distance between them and all drains and gas-pipes as great as possible. Suction of gases or liquids may occur into leaky pipes, even though these contain water, and still more when they are empty; and disease has occasionally been traced to this source. Thus if sewers and water-mains are laid in the same trench, foul matters which have escaped into the soil from the former may be sucked into the latter. This may happen if the water-mains are leaky, even when they are running full. Experiments have shewn that the flow of water causes a partial vacuum and insuction at the defective points. During intermissions of supply when the mains are partially or entirely empty, the danger of leakage into them is still greater. Coal-gas has been similarly sucked into water-mains.

The pipes bringing the water to a house may be kept constantly filled with water, or only for a limited time once or twice a day. The intermittent system of supply necessitates the provision of cisterns or water-tanks, in which water can be stored in the intervals of flow of water. With a sufficient and properly-distributed public supply of water, no cistern ought to be required.

Where the overflow-pipe discharges into the soil-pipe or closet pan, foul gases or even solid particles may find their way into the cistern.

With a constant supply of water, cisterns are only required for water-closets and for hot-water apparatus .

On the other hand it is urged that more expensive fittings are required for a constant service; and that, when taps are left open or pipes burst, the waste of water is much greater than with a cistern supply. The balance is decidedly in favour of a constant supply without storage cisterns. Where storage cisterns are in use, the taps for drinking-water should be connected with the "rising-main," before it supplies the cistern.

Owing to the absence of cisterns, the risks connected with stagnant water, and with improper arrangement of overflow pipes, are obviated.

The risk of suction into supply mains of external contaminations is reduced to a minimum, since the pipes are never empty.

The pipes are less liable to rust. Air in the presence of a little moisture, causes rapid corrosion.

There is an abundant supply of water in case of fire.

Of course, when there is a temporary stoppage of supply, as for repairs, some of the dangers incurred by an intermittent supply will arise.

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