Through kitchen and pantry sinks a large amount of grease, derived from washing dishes, etc,, is emptied into the drainage system. This grease proves to be of all the waste matters in the house the most difficult to deal with. Being dissolved by hot water it passes the strainer of the sink in a fluid condition, but soon becomes chilled, adheres to the sides of the waste pipes or drains, lodges in traps, and becomes putrid and offensive.

If the drain inside and outside of the house has a very good pitch, the grease will probably be carried far away from the house before becoming solid. This is more likely to happen where sinks have plugged outlets, as the rush of the water carries the grease very far. The ammonia of urine will remove grease, and thus pipes receiving above the point where the waste from the kitchen or pantry sink enters the cellar drain a water closet or urinal discharge are often found to be comparatively free from grease.

But in large houses, or hotels, etc, the grease should not be allowed to enter the house drain at all; it should be intercepted by a proper grease trap, placed as near to the sink as the locality may permit. The grease trap may be placed either within the house, in the basement or directly underneath the sink, or else outside the house. The latter arrangement is much the best, provided the distance from the kitchen sink to the grease interceptor is not too great, otherwise the grease would congeal on its way to the interceptor. A circular tank made of bricks, laid in hydraulic cement, should be constructed of dimensions depending somewhat upon the size of the house. It should be large enough to allow the water time to cool. Its overflow pipe consists of a quarter bend, or better, of a T branch, dipping at least six inches below the water line, in order not to disturb the grease in the intercepting tank. This grease trap should be frequently cleaned and inspected. The grease, floating on top of the water, can easily be removed. Efficient ventilation by a large vent pipe should be provided. Wastes from kitchen and pantry sinks only should discharge into the grease trap.

If inside of the house and in the basement, the grease trap may be made of earthenware, of wood lined with heavy lead, or of copper. But such a grease trap in the basement cannot be recommended.

If directly under the sink it may be made of enameled or galvanized iron, of copper or of crockery ware. A number of patented sinks have an iron receptacle for grease immediately below and attached to them. It is doubtful whether these tanks under sinks can be made of sufficient size, without becoming clumsy, to allow the grease to cool and congeal. Unless properly attended to - and the kitchen sink is liable not to be kept perfectly clean by the servants - grease traps inside of a house constitute, in my opinion, cesspools on a small scale, holding fatty waste matters which readily become putrid and offensive. If there is no convenient place for an outside grease trap, better use none at all and trust to the action of the alkalies to "cut" the grease in the pipes. A valuable cleansing agent for pipes, where the use of a grease trap is omitted, may be found in occasional flushing with hot solutions of common washing soda, or better, of potash.