In cold climates, indoor closets are especially desirable to obviate the exposure which can not be avoided when closets are out of doors. For invalids there should be a carefully managed earth closet kept in a well-aired room set apart for this purpose. In warm climates, earth closets should be frequently cleaned. To prevent the attraction of flies and insects and the too rapid decomposition of the contents a little unslacked lime added with the earth to the excrement will be of value. The discharges of persons suffering from typhoid-fever and bowel troubles should be mixed with thin slacked lime[1] (milk of lime). One-half to one hour after the mixing, such discharges may be put upon the soil, always at some distance from a well or spring, a stream, or a field under cultivation.
[1] Lime, to be used for disinfection, should not be air-slacked, but kept in tightly covered receptacles to prevent this from taking place.
In Europe, the use of earth and ashes has been superseded by peat dust. The upper layer of peat is dried in the air and ground in a suitable machine. The coarser particles are removed by sifting and used for bedding in stables. The fine portion, which has a very high absorbing power for fluids and is also capable of preventing odors, is used in dry closets. In Germany there are at present about thirty factories engaged in the preparation of peat moss for the purposes mentioned. Its great advantages over dry earth should bring it into use in our country. (See [fig. 5].)
It does not matter from a sanitary standpoint which one of the dry-earth systems is adopted, provided the necessary attention be given to it. Every system which can be recommended is bad if not properly attended to. The conditions to be observed are:
The night soil should be received in water-tight receptacles.
It should be frequently removed.
It should be utilized in the garden or field by being placed under a thin layer of soil.
To excreta from the sick, milk of lime or unslacked lime should be added before disposal in the soil.