Si quid novisti rectius istis, Candidus imperti, si non--his utere mecum. APPENDIX. To avoid overloading the text, I have thrown into the form of an Appendix several Notes more or less intimately connected with the great question considered in the body of the work. They may be read with or without any reference to the various headings they treat of. NOTE 1. By the deodorizing processes now in use, the ammonia, the most valuable constituent of manures, is destroyed; whilst by the flushing of sewers with an excessive quantity of water it is dissipated; hence the low value, or rather the absolute inutility of the sewage of large towns, as manure, when diluted with the surface drainage and other waters, excepting in the case of reclaiming waste lands, in order to convert them into meadows of so highly objectionable a character that no one can or will reside near them. The smell from such meadows is most abominable. Even in such cases an outfall must be provided for the surplus sewage waters, either into a river or into the sea, for the meadows to be irrigated require but little of it, and that only occasionally and during droughts. The fixing the ammonia is the great difficulty the agriculturist experiences in all questions respecting those manures which naturally contain or produce it. Its volatility is so great that it not only readily escapes into the air, but carries along with it, especially from waters, bodies at the moment in a state of slow combustion; or, in other words, ferments, capable of exciting fermentation in other fermentable bodies. It may even pass into the condition of caustic ammonia.[73] [73] It is to be remarked that the specific gravity of ammoniacal gas is 53·619; can it be wondered at that this gas should carry bodies from waters which are in a state of slow combustion; during its transit through the air it may even become caustic ammonia? In a well written pamphlet by Mr. Ward,[74] the unhappy and fatal mistake of mixing the surface drainage with the sewage of London is clearly pointed out for the hundredth time, but the parties who planned the scheme will no more take notice of such facts than they did fifteen or twenty years ago, when they commenced their work of polluting the Thames and other rivers. [74] _Purification of the Thames_. A Letter by F. O. Ward, Esq., addressed to William Coningham, Esq., M.P. London: Renshaw, Strand. To Mr. Ward’s proposal of purifying the river and fertilizing the land by tubular drainage, there are, however, many serious objections. NOTE 2.--_Habits of the_ WILDE, _in desert or uninhabited countries._