Faults in liquefying closets are objectionable odor, clogging of the screen over the outlet, or insufficient water in the vault to insure proper bacterial action. A ventilating pipe should be provided extending from beneath the seat to above the roof. The outlet pipe should not be less than 4 inches in diameter, and the mesh of the screen should not be less than one-fourth inch. The contents of the vault should be diluted with water at intervals, depending upon the number of persons using the closet and the rapidity of evaporation. Dilution may be effected by pouring in 1 or 2 gallons with a pail, or a small pipe may be led from the eaves trough of the closet to the vault. The effluent may be light colored and apparently inoffensive, but it still is sewage, and therefore the distributing tile never should be laid in the vicinity of a well or spring. DISINFECTANTS AND DEODORANTS. Disinfection is the destruction of disease germs. Sterilization is the destruction of all germs or bacteria, both the harmful and the useful. Antisepsis is the checking or restraining of bacterial growth. Deodorization is the destruction of odor. Unfortunately in practice none of these processes may be complete. The agent may be of inferior quality, may have lost its potency, or may not reach all parts of the mass treated. A disinfectant or germicide is an agent capable of destroying disease germs; an antiseptic is an agent merely capable of arresting bacterial growth, and it may be a dilute disinfectant; a deodorant is an agent that tends to destroy odor, but whose action may consist in absorbing odor or in masking the original odor with another more agreeable one.[6] [6] Those desiring more explicit information on disinfectants and the principles of disinfection are referred to U. S. Department of Agriculture Farmers' Bulletins 926, "Some Common Disinfectants," and 954, "The Disinfection of Stables," and to publications of the U. S. Public Health Service. Of active disinfecting agents, heat from fire, live steam, or boiling water is the surest. The heat generated by the slaking of quicklime has proved effective with small quantities of excreta. Results of tests by the Massachusetts State Board of Health[7] show that the preferable method consists in adding sufficient hot water (120° to 140° F.) to cover the excrement in the receptacle, then adding small pieces of fresh strong quicklime in amount equal to about one-third of the bulk of water and excrement combined, covering the receptacle, and allowing it to stand 1-1/2 hours or longer. [7] Annual Report, Mass. State Board of Health, 1914, pp. 727-729.