16. No brick, sheet-metal, earthenware, or chimney-flue shall be used as a sewer-ventilator, nor to ventilate any trap, drain, soil, or waste pipe. 17. Every vertical soil-pipe and waste-pipe must be of iron, and, where it receives the discharge of fixtures on two or more floors, it must be extended at least two feet above the highest part of the roof or coping, of undiminished size, with a return bend or cowl. It must not open near a window, nor an air-shaft which ventilates livingrooms. 18. Soil, waste, and vent pipes, in an extension, must be extended above the roof of the main building, when otherwise they would open within twenty feet of the windows of the main house or the adjoining house. 19. Horizontal soil and waste pipes are prohibited. 20. The minimum diameter of soil-pipe permitted is four inches. A vertical waste-pipe, into which a line of kitchen-sinks discharge, must be at least two inches in diameter, with one inch and a half branches. 21. Where lead pipe is used to connect fixtures with vertical soil or waste pipes, or to connect traps with vertical vent-pipes, it must not be lighter than D-pipe. 22. There shall be no traps on vertical soil-pipes or vertical waste-pipes. 23. All iron pipes must be sound, free from holes, and of a uniform thickness of not less than one eighth of an inch for a diameter of two, three, or four inches, or five thirty-seconds of an inch for a diameter of five or six inches; and, in case the building is over sixty-five feet in height above the curb, the use of what is known as extra heavy pipe, and corresponding fittings, are required, which weigh as follows: 2 inches, 5½ pounds per lineal foot. 3 ” 9½ ” ” 4 ” 13 ” ” 5 ” 17 ” ” 6 ” 20 ” ” 7 ” 27 ” ” 8 ” 33½ ” ” 10 ” 45 ” ” 12 ” 54 ” ” 24. Before they are connected they must be thoroughly coated inside and outside with coal-tar pitch, applied hot, or some other equivalent substance. 25. When required by an inspector from the Board of Health, the plumbing must be tested with the peppermint or the water test, by the plumber in the presence of the inspector, and all defective joints made tight, and other openings made impermeable to gases. Defective pipe discovered must be removed and replaced by sound pipe. 26. All joints in the iron drain-pipes, soil-pipes, and waste-pipes must be so calked with oakum and lead, or with cement made of iron filings and sal-ammoniac, as to make them impermeable to gas. 27. All connections of lead with iron pipes must be made with a brass sleeve or ferrule, of the same size as the lead pipe, put in the hub of the branch of the iron pipe, and calked in with lead. The lead pipe must be attached to the ferrule by a wiped joint. 28. All connections of lead pipe should be by wiped joints.