The _best_ manure within the reach of the farmer is _night soil_, or human excrement. There has always been a false delicacy about mentioning this fertilizer, which has caused much waste, and great loss of health, from the impure and offensive odors which it is allowed to send forth to taint the air. The value of the night soil yearly lost in the United States is, probably, about _fifty millions of dollars_ (50,000,000); an amount nearly equal to the entire expenses of our National Government. Much of the ill health of our people is undoubtedly occasioned by neglecting the proper treatment of night soil. [Describe this manure as compared with the excrements of other animals. Does the use of night soil produce disagreeable properties in plants?] That which directly affects agriculture, as treated of in this book, is the value of this substance as a fertilizer. The manure of man consists (as is the case with that of other animals) of those parts of his food which are not retained in the increase of his body. If he be _growing_, his manure is poorer, as in the case of the ox, and it is subject to all the other modifications named in the early part of this chapter. His food is usually of a varied character, and is rich in nitrogen, the phosphates, and other inorganic constituents; consequently, his manure is made valuable by containing large quantities of these matters. As is the case with the ox, the _dung_ contains the undigested food, the secretions (or leakings) of the digestive organs, and the insoluble parts of the ash of the digested food. The _urine_, in like manner, contains a large proportion of the nitrogen and the soluble inorganic parts of the digested food. When we consider how much richer the _food_ of man is than that of horned cattle, we shall see the superior value of his _excrement_. Night soil has been used as a manure, for ages, in China, which is, undoubtedly, one great secret of their success in supporting a dense population, for so long a time, without impoverishing the soil. It has been found, in many instances, to increase the productive power of the natural soil three-fold. That is, if a soil would produce ten bushels of wheat per acre, without manure, it would produce thirty bushels if manured with night soil. Some have supposed that manuring with night soil would give disagreeable properties to plants: such is not the case; their quality is invariably improved. The color and odor of the rose become richer and more delicate by the use of the most offensive night soil as manure. [What is the direct object of plants? What would result if this were not the case? How may night soil be easily prepared for use, and its offensive odor prevented?]