Cement joints shall be made with a narrow gasket of hemp or jute and cement mortar, and special care shall be taken to secure tight joints. The gasket shall be soaked in Portland cement grout and then carefully inserted between the bell and the spigot, and well calked with suitable hardwood or iron calking tools. It shall be in one continuous piece for each joint, and of such thickness as to bring the inverts of the two pipes smooth and even. The remainder of the joint shall be filled with cement mortar all around, on the bottom, top and sides, applied by hand with rubber mittens, well pressed into the annular space and beveled off from the outer edge of the bell to a distance of two inches therefrom, or to an angle of 45 degrees. The inside of each joint shall be thoroughly cleansed of all surplus mortar that may squeeze out in making the joint; and to accomplish this some suitable scraper or follower, or form shall be provided and always used immediately after each joint is finished. Cement joints so made, form the most satisfactory joint for ordinary conditions and are the most frequently used. They are not always water-tight and can be penetrated by roots. Some roots are able to penetrate holes of almost microscopic size and to form growths in the sewer or to split the joints. Poured joints are made by pouring some jointing compound, while in a fluid state, into the joint in which it hardens, thus sealing the joint. Water-tightness in sewer lines to exclude ground water has also been attempted by using the ordinary cement joint and surrounding the pipe with a layer of cement or concrete. This has not always been successful as it is difficult to obtain the proper class of workmanship in wet sewer trenches. The requisite qualities of a poured jointing material are: (1) It should make a joint proof against the entrance of water and roots. (2) It should be inexpensive. (3) It should have a long life. (4) It should not deteriorate in sewage which may be either acid or alkaline. (5) It should adhere to the surface of the pipe. (6) It should run at a temperature below about 400° F., as too high temperatures will crack the pipe. (7) It should neither melt nor soften at temperatures below 250° F. in order to maintain the joint if hot liquids are poured into the sewer. (8) It should be elastic enough to permit slight movements of the pipes. (9) It should not require great skill in using as it must be handled ordinarily by unskilled workers.