Sometimes the smell of the drains will be carried into a house through a fireplace; and, where the smell is particularly noticeable near a fireplace in warm weather, this may be suspected. In summer, when the house is cool, and the outside air warm, it is very common, particularly in city houses, for the current in the flues to be reversed, the cool brickwork chilling the air in the flues until it is heavier than a column of outside air of the same section and height. When this occurs, the air in the flues will descend, bringing with it into the rooms the "sooty smell" characteristic of rooms in old houses which are kept shut up in hot weather; and the same current which conveys the fragrance of the soot in an old chimney brings also down the flue a portion of whatever vapors may be hanging at the time around the top of the chimney. Among these are often exhalations from the open top of a soil-pipe which is carried up beside the chimney; and the quantity of such exhalations is not unfrequently sufficient to make them very distinctly appreciable to people sitting or standing near a fireplace in communication with the flue. As the testing of the waste-pipes throws no light on a condition of this kind, its existence may be suspected in cases where mysterious smells have baffled the intelligence of the local plumber.

L

When careful examination of the pipes and fixtures shows no visible leaks, or other means of communication between the air of the house and that of the drains, the pipes, if the smell which it is desired to investigate still continues, and cannot be traced to a dead rat, or mouse, or to bad eggs or scraps of meat in the ash-barrel, or to remains of glue-size left by painters or paper-ers, should be tested. This is thoroughly and scientifically done by engineers who make it a part of their professional work, or by the best plumbers; but the householder who has not a first-rate plumber within reach can easily make a satisfactory test for himself.

For this purpose two ounces of oil of peppermint should be procured. Druggists very generally keep oil of peppermint in two-ounce glass tubes, hermetically sealed, for plumbers' use; but, if those are not available, a well-corked bottle will answer. Armed with the oil of peppermint and a pail or pitcher of hot water, some one should be sent, if possible, to the roof, to pour the peppermint into the top of the soil-pipe; but, if it is impracticable to reach the top of the pipe, the oil may be poured into the highest sink, basin, or other fixture in the house, keeping the door of the room in which the fixture is placed tightly closed. The tube of oil is to be broken, or the bottle uncorked, and the contents poured into the soil-pipe, or the waste-pipe of the fixture, followed immediately by the hot water. The warm water washes the oil down the pipe, at the same time that its heat volatilizes it, diffusing the vapor through the whole system of waste and air pipes; and, as soon as it is poured down, the opening through which it was poured should be tightly closed, by stuffing in paper or otherwise, to increase the thoroughness of the diffusion of the vapor, and prevent its escape. The person deputed to pour the peppermint into the pipes should not come into the house, or leave the room in which he operates, until the test is over, as he would bring so much of the perfume with him as to vitiate the test. Supposing care to have been taken in regard to this point, any smell of peppermint in the house will indicate a defect in the waste or air pipes near the place where the odor is perceived; and closer inspection will generally determine the exact location and character of the defect, which may, in many cases, be remedied by recaulking, or by the application of putty. Where a pipe is broken, or rusted through, the smell of peppermint will be so strong as to call immediate attention to the trouble, and, in such cases, the pipe must be renewed.

Testing with peppermint.

It is desirable, after such leaks as may be disclosed by the peppermint have been stopped, to repeat the test; and the householder may be sure that no sewer-gas can escape into his rooms from pipes which are tight enough to keep in the vapor of peppermint applied in this way.

Repetition of test:

If, as is sometimes the case in large houses, or in those built some years ago, when plumbers had a mania for extending air-pipes through the roof, there is more than one pipe projecting above the roof, all such pipes, except the one into which the peppermint is to be poured, should be temporarily closed with wads of paper, to prevent the current which generally exists in house-pipes from drawing off the vapor before it has diffused itself through the entire system. As all the waste-pipes in the house, however numerous, join inside of the main trap, it is only necessary to pour the peppermint into one pipe to fill the whole system with the vapor; but the washing down of the oil with hot water is an essential feature of the test, as without it there is no certainty that enough vapor will be generated to fill all the pipes.

In some houses, built when plumbers were less enlightened than they are now, or when inspection was less rigid, soil-pipes, instead of being carried up through the roof, may be found entered into a chimney-flue, often the range-flue, probably with some vague notion of ventilating the fixtures, just as, in modern plumbing, the local vent of a water-closet is connected with a heated flue. It is hardly necessary to say that the modern local vent has nothing to do with the drains, simply conducting the air of the room into the flue through the bowl of the water-closet; while the soil-pipe, on the other hand, being separated from the water-closet basin by the sealing-water of the trap, can do absolutely nothing to ventilate the closet, and serves only to contain, and guide to a safe outlet, the air of the drain; so that the only result of connecting a soil-pipe, or a back-vent pipe from a trap, with a chimney-flue is to saturate the porous brickwork of the chimney with foul odors, which soon diffuse themselves into the rooms through which the chimney passes. An objectionable arrangement of this kind often exists undiscovered in old houses, and may be suspected where a foul odor hangs persistently about rooms which have a chimney passing through them, but no pipes. The peppermint test may be used to confirm these suspicions, but, as the peppermint vapor penetrates the brickwork very slowly, repeated trials may be necessary.