A system of practical medicine. By American authors. Vol. 1

by Unknown

The sanitary inspection of a house includes the site and the building itself. The character of the site is mainly determined by its dryness, by the presence or absence of organic matter in the soil, and by its porosity taken in connection with the character of the vicinity. One-third of the volume of some soils consists of air, and all dry soils and rocks contain a much larger quantity of air than is commonly supposed. The influence of soil upon health is exerted mainly through the media of water and air, but it also affects temperature and vegetation, being an important factor in climate. Residence on a damp soil has a tendency to produce diseases of the lungs, and especially phthisis; but how it does this is unknown, though it would be easy to construct a plausible theory in connection with the supposed causation of phthisis by a bacillus. The practical point for the physician is, that the prevalence of phthisis in a locality, even if it be so limited as to comprise but a single house, should cause suspicion and investigation as to the character of the soil-drainage. Soil-moisture is also an important factor in the development of periodical fevers, and the effect of thorough drainage in diminishing malaria is now generally understood.

It sometimes becomes an important question as to the influence which a collection of water, such as a mill-pond or a reservoir, has upon the health of a community, and the physician may be called on for an opinion in such cases where large property interests are involved. The essential points to be borne in mind are—first, that stagnant water and damp soil do not in themselves produce malaria; there is something else necessary, which is commonly designated by the word "germ." Second, that they are in most cases essential conditions for the production of the disease, so that if removed the disease will disappear. Third, that the development of malaria may follow either the rise or fall of the ground water. Fourth, that the condition of the border of the collection of water as to presence of organic matter and moisture is of more importance than the pool itself. And, finally, that each case is a problem by itself, to be determined by the history of the sickness of the vicinity, and that only probabilities can be stated in any case, although these probabilities may be so great as to amount, practically, to certainty. Of the four factors which appear to be essential to the production of the malarial poison—viz. moisture, high temperature, organic matter of vegetable origin, and certain micro-organisms—the first is the one which in any given locality is most under human control; it is the link in the chain of causation which is most easily broken.

The influence of the rise and fall of the soil water in typhoid fever, upon which so much stress is laid by Pettenkofer and others, no doubt exists, acting in some cases through pollution of the drinking water by the subsoil water leaking through a polluted soil; in other cases, perhaps, by air from the soil bearing the unknown germ. The filtering power of soil as regards air is, however, very great, a few inches of sand being sufficient to remove the ordinary germs of putrefaction from air drawn through it, and this for a long period; while, on the contrary, many feet of the same sand will not remove the germs from water passed through it. Usually, as Dr. Parkes remarks, in an examination of soil the immediate local conditions are of more importance than the general geological formation, yet this last, as influencing conformation and the movement of water and air over and through a country, is also important. The practical questions on this point are, what higher ground than the site in question exists in the vicinity? what are the character and direction of the strata between such elevation and the site? and, what sources of soil-pollution exist on the higher level? As to the site itself, is it on made ground? what is the height of the foundation above the subsoil water? and, what precautions have been taken to secure drainage and to cut off communication between the interior of the house and the ground air? Probably a trial excavation or boring may be necessary to determine some of these points.

The level of the subsoil water should be at least five feet below the foundations, although it is often impossible to obtain this. At all times when the temperature of the house is higher than that of the external air—i.e. during a large part of the year and nearly every night—there is a strong and constant aspirating force at work to draw into the house, through the cellar floor and walls, all gases and vapors contained in the adjoining soil. If this soil contains a large proportion of organic matter, as is often the case in filled-in ground in cities, or if there be a leaky cesspool or sewer or gas-pipe under or near the house, the ground air passing into the house may be of such a character as to be positively dangerous to its occupants. For this reason it is very undesirable to have a sewer or soil-pipe crossing beneath the site of a house, and when such location is a necessity, as it often is in cities, the soil-pipe should be laid in a cement-lined trench covered with a movable flap, so that it can always be easily inspected and any leaks detected and remedied. Dampness in the cellar or basement of a house is always a sign of danger. The exhalation of gases and vapors from the ground into the house can be to a great extent cut off by a layer of impervious material, such as concrete covered with asphalt, but this layer must cover the sides of the cellar as well as the floor to be thoroughly efficient. If a house have no cellar, the space between the floor and the ground should be thoroughly ventilated; and for this purpose, as well as to secure cleanliness, the floor should be sufficiently elevated to permit of easy access beneath it.

Next to its dryness, the nature and condition of the arrangements for removing excreta and soiled water from a house are of the greatest importance in determining its healthfulness; and in cities it is with regard to the sufficiency of these, including the whole system of house-plumbing and pipe-fitting, that the inquiries of one wishing to determine as to the presence or absence of causes of disease will most frequently be directed. The soil-pipes, etc. of a house are commonly referred to as constituting the system of house-drainage, but it is desirable to use another term, for we need the word "drainage" to describe the removal of surface and subsoil water, and it should be distinguished from "sewerage," which has a different purpose and requirements.

In a properly-arranged system of house sewerage all the pipes, traps, etc. are easily accessible for purposes of inspection, and an examination of them is a comparatively simple matter. This examination is to be made with reference to the following points: 1. Are all the pipes, joints, and connections air-tight? 2. Is the soil-pipe well ventilated, or has it dead ends? 3. Is the communication between the soil-pipe and the street sewer uninterrupted? 4. Are the pipes properly trapped, and is there liability to the removal of water from any of the traps, either by siphonage or evaporation, to such an extent as to break the seal? 5. Is the water-supply of each closet entirely cut off from the main supply to the house by means of a tank or cistern?

In houses as heretofore constructed it is often very difficult to obtain satisfactory information upon these points, because a large part of the soil-pipe and its connections is buried beneath the house or concealed in the walls or floors; in which case the services of a skilled mechanic will usually be necessary to obtain access to the various parts of the system. In a paper of this kind it is of course impossible to go into details as to methods of inspection, or as to what is and what is not satisfactory; but the following are the general principles upon which a judgment as to the merits of a system should be formed, and these should be so clearly understood by every physician that he can be neither persuaded nor frightened into thinking them incorrect by the eloquence of the man with a patent remedy to dispose of. The principal dangers to health from house sewerage are due, first, to the passage of air from the general system of sewers or from a cesspool into the house through the soil-pipe and its connections; second, to the generation of offensive and dangerous gases and organisms in the soil-pipe itself, and the passage of these into the house; third, to leakage of soil-pipe causing contamination of the water-supply either by improper connections of water-pipes with water-closets or slop-hoppers, or by contamination of wells, cisterns, or tanks with sewage or sewer gases.

There is, of course, no such thing as a sewer gas having a definite and distinctive composition, and the nature of the mixture of gases in sewers is constantly varying according to season, temperature, etc. The tendency which sewer air has to cause disease depends in part upon certain gases, in part on minute particles of solid or semi-solid matter which are suspended in the air. In rare instances the sewers also contain illuminating gas, derived from leakage of gas-pipes in the vicinity. These gases produce debility, headache, loss of appetite, etc. As found in sewers and soil-pipes, they are so diluted that they are not absorbed by the water of a trap and given off on the other side to a sufficient extent to produce an evil effect. The air in a soil-pipe which is not ventilated is much more impure than that of the ordinary sewer, since the process of decomposition is constantly going on in the slimy coat which lines the interior of the pipes; and it is for this reason that it is so important to secure thorough ventilation of all the soil-pipes in a building. When this ventilation is secured, the proportion of dangerous gas in the pipes becomes very small, and the amount absorbed by the water in traps is almost inappreciable. The chief danger to life from sewer and soil-pipe air arises from the presence of minute particles of organic matter, dead and living, the so-called germs. Danger to life from these germs cannot be entirely removed by dilution, as can be done with gases. It has been found by the experiments of Dr. Carmichael and Dr. Wernick that an ordinary water-trap entirely prevents the passage of these germs, and that organic putrescible fluid will remain unchanged when exposed only to the air immediately above such a trap. A pin-hole or minute sand-crack in the soil-pipe, or a very slight defect in a joint, is far more dangerous than a trap.

The forms of disease produced by sewer air and its contents are more especially diphtheria, typhoid fever, and ill-defined disorders of the throat and digestive organs. It is possible that the germs of other specific diseases, such as scarlet fever, may be at times transmitted through sewer air, but such transmission must be very rare. While it is true that the germs of the specific diseases are very rarely present in sewer air, the house system of sewerage must be arranged as if they were always present, in order to obtain security. It must also be remembered that a system originally well planned and properly constructed will not always remain so; the pipes will corrode, the joints will become loosened, the valves will become clogged, and whenever alterations or repairs are made there is always danger of injury. Bearing these points in mind, the method of investigating a system can be readily understood.

The first step is to ascertain whether there is a trap outside the house disconnecting the sewer from the house system and permitting inspection. If there is not, the first thing to be done is to make an excavation and open the drain at the proper point for placing such a trap. The next step is to set the water flowing in the various closets and watch the flow at the external trap, or opening, which has been made to ascertain whether there is any obstruction in the pipe within the house. If the sewer is properly arranged for inspection, as has been above suggested, to determine whether there is any leakage from the sewer under the house will be an easy matter; if, however, it is buried beneath the cellar floor, as is usually the case, an excavation should be made along the floor in the line of the pipe, with a view to having it properly arranged, as well as for the purpose of examining the soil. It may also be tested by opening the upright soil-pipes at the farther end of the house-drain at the height of three or four feet above the floor and pouring water into it, having temporarily stopped up the drain at the external trap or opening. If the water remain at a constant level in the upright piece, the sewer is water-tight; if not, the leakage may be ascertained by the rate at which it sinks. Having settled this, the next point is to determine whether all the soil-pipes are air-tight and properly trapped. The test usually applied for this purpose is the pouring of a small quantity of strong oil of peppermint, followed by a dash of hot water, into the top of the soil-pipe, which should always pass through the roof and be freely opened to the outer air. If the odor of the oil is perceptible in the house, it indicates a leak, which must be further sought for. Ether may be used for the same purpose. The smoke test is, however, the best, but it requires a special apparatus which as yet is little used in this country. It is applied by a small machine with a fan, by which the smoke from burning cotton-waste saturated with oil, or of coarse brown paper impregnated with sulphur, can be blown into the pipes; this locates leaks with great precision.