18 INORGANIC MANURES, CONSIDERED 



tion ; whereas, the dung of which a hotbed is formed cannot be removed 

 without destroying the bed and the crop on it ; and hence it is gene- 

 rally kept till the fermenting process is carried much further than is 

 necessary, and often so far as to be injurious. Hence, in gardens, 

 wherever economy of manure is an object, common hotbeds ought 

 never to be made use of, but recourse should be had to exterior 

 casings, such as those already mentioned, or to other modes of heating. 

 In many suburban villas, almost as much manure is lost as would 

 suffice for enriching the kitchen-garden, and producing vegetables 

 for the whole family. To save every particle of fluid or solid matter 

 capable of becoming manure, the first step is to construct two or more 

 large tanks for the liquid manure, and to form a system of tubes or 

 gutters for conveying to these tanks all the soapsuds and other liquid 

 refuse matters furnished by the mansion and offices, includ- 

 ing the stables, unless they are at a distance. Similar tanks should 

 be formed adjoining every cottage and dwelling belonging to the villa ; 

 such as the gardener's house, gatekeeper's lodge, and also in the back- 

 sheds and in the frame and reserve ground of the kitchen-garden. In 

 short, no water ought to be allowed to escape from the manure tanks 

 but such as is perfectly pure ; for all dirty water is more or less valu- 

 able as a manure, and will ferment in a degree of heat not much 

 greater than that of the subsoil, even in winter ; and all fermented 

 liquids contain one or more of the constituent elements of plants. The 

 second step to be taken with a view to saving manure is, to form a 

 vegetable rubbish heap, on which all waste parts of plants and the re- 

 mains of all crops, including mown grass when not otherwise used, clip- 

 pings of hedges, summer prunings of trees, &c., are to be thrown as col- 

 lected, left to ferment, and turned over occasionally. To this heap, lime, 

 dung, sewage, or rich earth may be added, and the whole frequently 

 turned over and well mixed. The third step is, to collect the cleanings 

 of ponds, wells, ditches, hedge-banks, and similar earthy matters, and 

 mix them with quicklime, turning the heap occasionally, as directed in 

 the next section. 



Inorganic Manures. 



Inorganic or mineral manures are chiefly : lime in a state of chalk or 

 carbonate, gypsum or sulphate, marl in which carbonate of lime is 

 mixed with clay, saltpetre, kelp, mineral alkali, and common salt. 

 The organic manures, as we have seen, act by supplying plants with 

 the elements of which they are constituted, viz., carbon, oxygen, hydro- 

 gen, and azote or nitrogen ; but the mineral manures contain none of 

 these elements, and hence, according to most agricultural chemists, 

 they must act beneficially on some other principle. This principle may 

 be stated to be the rendering more soluble of the organic matters 

 already in the soil in most instances, and in some cases rendering 

 soluble matters insoluble, so as to diminish excessive fertility, and pre- 

 pare a reserve of the fertilizing principle for future use. Quicklime, 

 for example, effects the first of these objects, and slaked lime the 



