For molding hot compounds, a clay dike, or funnel, built about 3 inches high around the triangular opening at the top of the jointer greatly aids in the rapid and complete filling of the joint space. A hot joint must be poured continuously, otherwise a seam may develop between successive pourings. Bituminous compounds make a slightly elastic joint. A joint in 4-inch pipe requires about 3/8 to 1/2 pound of compound and in 6-inch pipe about 1 to 1-1/2 pounds. Sulfur-sand joints are hard and inelastic. The compound is made by mixing together equal volumes of ordinary powdered sulfur and very fine clean sand, preferably the finest quicksand, and then heating the mixture until the sulfur melts. A 4-inch joint takes about 3/4 pound and a 6-inch joint about 1-7/8 pounds of the mixture. Commercial sulfur-joint compounds also are available. [Illustration: Figure 3.--Jointing sewer pipe. _A_, Using calking iron to force packing into joint. _B_, Making joint with 1:2 portland cement mortar. Use only enough water to dampen the mix. Recalk after half an hour, to close shrinkage cracks. _C_, The completed joint. Wrap finished joint with cloth and keep dampened, to aid curing. _D_, Joint made by pouring 1:1 Portland cement grout of creamy consistency into a form. This type of joint is not feasible unless the metal forms shown are available. _E_, Use of asbestos runner clamped around pipe, for pouring hot joint. _F_, Clay roll used in place of asbestos runner. _G_, A completed bituminous joint. _H_, Use of swab, to remove any joint material forced through to inside of pipe.] Soft pig lead or old scrap lead is suitable for lead joints on cast-iron pipe. About 3/4 pound per inch of pipe diameter is generally required for each joint. The lead is hot enough to pour when it begins to char the paddle used to skim off the impurities. When it cools it must be calked tightly to take up shrinkage. The calking should be uniform around the entire joint and should stop when the lead is tight. Heavy pounding or continued calking may crack the bell of the pipe. It is easier to get good, joints when the pipe is in a vertical position. Therefore, two lengths of pipe are frequently joined and are then laid as a single unit in the trench. In using terra cotta pipe, this procedure may be followed only when the joint is made with a mastic compound. Cement-mortar joints cannot be used in such cases. Before filling the trench, the sewer should be tested to detect possible leaks. Earth free from rubbish and large stones should then be tamped around and about 1 foot above the pipe. THE SEPTIC TANK Flow Through the Tank Slow, undisturbed flow through the tank is necessary for the separation of solids and liquids and for bacterial action. Submerged inlets and outlets or baffle boards reduce disturbance. A submerged outlet prevents scum from passing out with the effluent.