APPENDIX A.

CONSTRUCTION AND MAINTENANCE OF A SANITARY PRIVY.

"The prevention of typhoid fever in the United States to-day depends on an improvement in the present methods of disposing of human excreta. Until all the people can be taught that the most dangerous material with which they come in contact in their daily lives is filth from human bodies, and until their sanitary habits are so changed that human filth is prevented from reaching human mouths, the prevention of typhoid fever can not be consummated." (From the Report of the Committee on Typhoid Fever to the Section on Preventive Medicine and Public Health of the American Medical Association, at the Sixtysecond Annual Meeting, held at Los Angeles, June, 1911. Journal Am. Med. Assn., Sept. 9, 1911, Vol. LVII, pp. 891-895.)

A privy to be sanitary must meet the following requirements:

(1) The excreta must be received in a water-tight receptacle (tub, pail, box, barrel, tank, or vault) so that pollution of the soil under and around the privy is prevented, and so that the excreta may be readily removed from the privy and safely disposed of.

(2) Flies and other insects, domesticated animals, and all other living creatures liable to scatter disease germs must be prevented from having access to the excreta.

Any type of privy, no matter how simple and cheap, which meets these requirements is sanitary, and any type of privy, no matter how elaborate and costly, which does not meet these requirements is insanitary.

Two types of sanitary privies are generally recognized, namely, the so-called "dry system" and the so-called "wet system." In the " dry-system" privies, dry earth, wood ashes, or lime is kept in the privy and is sprinkled liberally over the excreta in the receptacle under the privy seat every time the privy is used. In the "wet-system" privies some fluid is used in the receptacle either (1) to disinfect the excreta, or (2) to serve as an insect repellant, or (3) to aid in the liquefaction of the excrement by natural fermentations.

Figures 6 and 7 represent an outhouse which may be used either as a "dry system" or as a "wet system" privy. Note (1) the water-tight receptacle under the seat, (2) the screening (w) over the ventilators to keep out flies, (3) the cover (k) over the seat to prevent flies, which may occasionally get into the house as persons pass in and out through the door, from having access to the excreta in the receptacle, and (4) the back trapdoor (oc') to prevent animals from having access to the receptacle. The trapdoor should be kept closed down except when the receptacle is being removed or replaced. If the location of the privy is such that there is no particular advantage in removing the receptacle, for the purpose of emptying and cleansing it, through the rear of the house the construction of the privy may be simplified somewhat by having the back of the house boarded up solidly and the seat and

The construction and the advantages and the disadvantages of different types of privies are given in detail in a recent article prepared by C. W. Stiles and L. L. Lumsden and published by the U. S. Department of Agriculture as Farmers' Bulletin 463. Copies of this bulletin, entitled "The Sanitary Privy," may be obtained without cost by sending a request to the Department of Agriculture or to a Congressman.

the receptacle arranged as in figure 8. In fact, the receptacle with the seat and framework over it, as shown in this figure, may be placed in one of the outhouses, such as the barn, stable, or a shed already on the premises-thus saving the expense of building a special house for the purpose. If the receptacle is of sufficient stoutness to support the weight of a person sitting on it the contrivance may be still further simplified by dispensing with the box around the receptacle and having only a simply constructed and readily removable seat fitted tightly over the top of the receptacle, as indicated in figure 9. Whatever place the contrivance is kept in for use should be screened, otherwise flies are very liable to gain access occasionally through the hole in the seat to the excreta in the receptacle. This is particularly true if all persons using the contrivance are not very careful to keep the cover over the hole closed down except when the seat is occupied.

As a receptacle for the excreta any vessel which is water-tight may be used. The half of an oil barrel or a vinegar barrel, an ordinary wooden tub, a tin pale, a stone jar, a box made of boards and either zinc lined or heavily tarred, or even an ordinary candy bucket, which costs only 10 cents, will serve the purpose; but for safety, convenience, and (in the long run) economy, a tub, can, or pot made of iron and which will withstand repeated heatings to the boiling temperature has advantages. The receptacle should fit snugly under the seat so that there will be no space between the framework of the seat and the top of the receptacle through which flies or other insects may pass.

The privy should be maintained so that the contents of the receptacle will be free from decidedly disagreeable odors and in such form as to be conveniently removable for safe ultimate disposal. It is much safer to keep a disinfectant solution in the receptacle, so that all disease-producing bacteria in the excreta will be killed as the excreta are deposited in the privy, than it is to use a disinfectant only when the receptacle is to be emptied.

If dry earth, wood ashes, or dry air-slaked lime are sprinkled liberally over the excreta in the receptacle every time the privy is used the privy contents will be kept free from markedly disagreeable odors, but not all disease germs in the excreta will be killed, and the contents of the receptacle, being solid, can not be disinfected so readily and disposed of so conveniently and safely as they can be if kept in liquid form. If water is added and sufficient time allowed the natural fermentation or septic action will liquefy the excrement, and, due to evaporation and the evolution of gases, may lessen somewhat the volume of the excreta to be disposed of. If this "wet system" is applied to the ordinary type of sanitary privy (see fig. 7) the receptacle should be filled about one-fourth full of water and a cup of petroleum poured on the surface of the water to serve as an insect repellant. Two sets of receptacles should be provided. While one set is being used under the seat the other set should be covered and permitted to stand for about a week so as to lengthen the period of fermentation. The disadvantages of this system are the splashing, the frequency of emptying needed to prevent offensiveness, the liability to freezing, the expense of an extra set of receptacles, and the care needed to prevent the liquefied but still potentially infectious excreta from being spilt about when the cans are being removed or emptied. These disadvantages appear to more than surmount the slight advantages to be obtained from the natural fermentation or septic action, and in maintaining the ordinary type of sanitary privy (figs 7, 8, and 9) it seems much safer to use a disinfectant solution in the receptacle.

A disinfectant may be used conveniently and cheaply and under practically all climatic conditions as follows: Keep a vessel containing the disinfectant solution in or convenient to the privy and every time the privy is used for

FIG. 7.-REAR AND SIDE VIEW OF A SINGLE-SEATED SANITARY PRIVY.

LH-WILDER

FIG. 8.-SANITARY PRIVY CLOSED IN BACK.

Box encasing receptacle is detached from structure of the house. Such a commode may be kept for use in a room in the dwelling house or in a barn or stable.

defecation or urination, or both, pour about 1 pint of the solution into the receptacle. As the solution is added along with the excreta and the toilet paper the contents of the receptacle will be kept at a sufficient consistency to prevent objectionable splashing, and will be also free from decidedly objectionable odor. Furthermore, since most or all of the disease-producing bacteria in the excreta will be killed by the disinfectant solution, the chances for the occasional fly which may gain access to the contents of the receptacle to spread infection from the excreta will be greatly lessened. When the receptacle has become about two-thirds full it should be filled nearly to the top with the disinfectant solution and left standing for an hour or two, or more when convenient, before being emptied. For ultimate disposal privy contents treated in this way may be emptied in the manhole of a sewer (when practicable) or buried. If burial is resorted to the matter should be deposited not less than 300 feet from and downhill from any sources of water supply and not less than 2 feet underground.

Since chemical disinfectants can not be relied upon to destroy certain animal parasites liable to be in human excreta, chemically treated night soil should not be used as fertilizer, nor thrown out on the surface of the ground, nor carelessly buried.

Any one of the following disinfectant solutions may be used in the way described above for maintaining a wet-system" privy:

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(1) Chloride-of-lime solution.-Add 1 pound of good (fresh) chloride of lime to 8 gallons of water. Shake well and keep the solution in a well-stoppered vessel. This solution has the great advantage of cheapness and is thoroughly efficient. Dry chloride of lime which is exposed to the air rapidly loses its disinfectant properties. Chloride-of-lime solution if exposed to the air gradually loses its disinfectant properties. These facts should be kept in mind and precautions taken accordingly in the preparation and storage of the solution.

(2) Quick lime solution.-Made by adding good unslaked lime to water in the proportion of 10 pounds of lime to 10 gallons of water, just in the way that ordinary "whitewash" is made. Lime which has become air-slaked will not make a reliable disinfectant solution. Lime which does not steam up when added to water is not good. A barrel of milk of lime or "whitewash" can be made up conveniently at one time and kept with a tight-fitting cover over it in or near the privy and the solution added to the contents of the privy receptacle as needed. The milk of lime should always be well stirred up before being used.

(3) Carbolic-acid solution.-Add 1 pint of carbolic acid to 19 pints of water. If the ordinary "crude carbolic acid," which is only slightly soluble in water, is used, some soap or caustic potash or soda should be added to make a uniform emulsion. Carbolic solution has the advantage of retaining its disinfectant properties when exposed to the air, but has the disadvantages of being a dangerous poison and of being more expensive than solutions (1) and (2). If a suitable (metallic) vessel is used for the receptacle, a fire may be built under the vessel and the excreta heated to boiling temperature (212° F.). If a wooden or concrete tank is used, the excreta may be transferred to some other vessel for heating. After disinfection by heat human excreta may be safely used for fertilizer.

From what has been said above it is clear that some intelligent care, labor, and expense are required to maintain a privy in sanitary condition. The re sults in the saving of human life and health and in the prevention of economic loss unquestionably more than justify the cost.