The ordinary =privy-vault= should never be allowed. Its only advantage is its cheapness, while it involves constant danger of contamination of the water of adjoining wells or cisterns. Many an epidemic of typhoid fever has been unmistakably traced to this source. If such a vault is a necessity, it should be made water-tight, be small and frequently emptied, the contents should be frequently disinfected, preferably by being covered with fresh earth, and it should be built in such a spot that the current of ground-water (which furnishes the well-water) shall be from the well toward the vault, and never in the opposite direction. Better still is a =movable tank=, in which the excreta are received and covered with fresh earth daily. This can be emptied over a garden or field without offense. In villages where sewerage is impossible, =pails= are sometimes used. They have tight covers, and are removed frequently (once or twice a week, clean ones being substituted at the time of removal by the proper authorities), the contents being converted into poudrette at some place remote from habitations. A better means of disposing of the excreta, where water-closets can not be had, is the =earth-closet=, of which there are several varieties. These are so constructed that they resemble a water-closet in appearance, but the excreta are caught in a receptacle beneath the seat, and covered with earth, when the handle beside the seat is raised. Dry earth is an excellent disinfectant,[1] and when excreta are thus mingled with it they are gradually oxidized and disappear, so that after a time the same earth may, with proper precautions, be used again. [1] Its disinfectant properties have been shown to be due to the presence of microscopic organisms, which decompose the excreta in the act of nourishing themselves. A little chloroform paralyzes them, and deprives the earth of its disinfecting properties, which return, however, when the chloroform is washed out, and the organisms recover their natural vigor. The earth for these closets must be dry, and sifted of coarse particles, and enough must be deposited upon the excreta to cover them and to absorb the urine. Its advantages, as compared with the water-closet, are, that it is cheaper, requires less repair, is not hurt by frost, is not injured when improper substances are thrown down it, and requires no water. Its disadvantages are, the trouble of collecting and drying the earth, the necessity of frequently removing the soil, the dust sometimes caused by its use, and the necessity of providing additional means for the disposal of slops.