Book III. SPECIES OF MANURES. 331 



the atmospheric temperature and pressure were nearly the same as at the commencement 

 of the experiment. Some water rushed in ; and on expelling a little air by heat from the 

 tube, and analysing it, it was found to contain only seven per cent, of oxygen. The 

 water in the tube, when mixed with lime-water, produced a copious precipitate ; so that 

 carbonic acid had evidently been formed and dissolved by the water. 



2180. Manures from animal substances, in general, require no chemical preparation to 

 fit them for the soil. The great object of the farmer is to blend them with the earthy 

 constituents in a proper state of division, and to prevent their too rapid decomposition. 



2181. The entire parts of the muscles of land animals are not commonly used as manure, 

 though there are many cases in which such an application might be easily made. Horses, 

 dogs, sheep, deer, and other quadrupeds that have died accidentally, or of disease, after 

 their skins are separated, are often suffered to remain exposed to the air, or immersed in 

 water, till they are destroyed by birds or beasts of prey, or entirely decomposed ; and in 

 this case, most of their organised matter is lost for the land in which they lie, and a con- 

 siderable portion of it employed in giving off noxious gases to the atmosphere. By 

 covering dead animals with five or six times their bulk of soil, mixed with one part of 

 lime, and suffering them to remain for a few months ; their decomposition would im- 

 pregnate the soil with soluble matters, so as to render it an excellent manure ; and by 

 mixing a little fresh quick-lime with it at the time of its removal, the disagreeable effluvia 

 would be in a great measure destroyed ; and it might be applied in the same way as any 

 other manure to crops. 



2182. Fish forms a powerful manure, in whatever state it is applied ; but it cannot be 

 ploughed in too fresh, though the quantity should be limited. A. Young records an 

 experiment, in which herrings spread over a field, and ploughed in for wheat, produced 

 so rank a crop, that it was entirely laid before harvest. The refuse pilchards in Corn- 

 wall are used throughout the county as a manure, with excellent effects. They are 

 usually mixed with sand or soil, and sometimes with sea- weed, to prevent them from 

 raising too luxuriant a crop. The effects are perceived for several years. In the fens of 

 Lincolnshire, Cambridgeshire, and Norfolk, the little fishes called sticklebacks, are 

 caught in the shallow waters in such quantities, that they form a great article of manure 

 in the land bordering on the fens. It is easy to explain the operation of fish as a ma- 

 nure. The skin is principally gelatine ; which, from its slight state of cohesion, is readily 

 soluble in water : fat or oil is always found in fishes, either under the skin or in some of 

 the viscera ; and their fibrous matter contains all the essential elements of vegetable 

 substances. 



2183. Amongst oili/ substances, blubber has been employed as a manure. It is most 

 useful when mixed with clay, sand, or any common soil, so as to expose a large surface 

 to the air, the oxygen of which produces soluble matter from it. Lord Somerville used 

 blubber with great success at his farm in Surrey. It was made into a heap with soil, 

 and retained its powers of fertilising for several successive years. The carbon and 

 hydrogen abounding in oily substances, fully account for their effects ; and their dura- 

 bility is easily explained from the gradual manner in which they change by the action of 

 air and water. 



2184. ^onej are much used as a manure in the neighborhood of London. After being 

 broken, and boiled for grease, they are sold to the farmer. The more divided they are, 

 tlie more powerful are their effects. The expense of grinding them in a mill would 

 probably be repaid by the increase of their fertilising powers ; and in the state of powder 

 they might be used in the drill husbandry, and delivered with the seed, in the same 

 manner as rape-cake. Bone-dust and bone-shavings, the refuse of the turning manu- 

 facture, may be advantageously employed in the same way. The basis of bone is con- 

 stituted by earthy salts, principally phosphate of lime, with some carbonate of lime and 

 phosphate of magnesia ; the easily decomposable substances in bone, are fat, gelatine, 

 and cartilage, which seems of the same nature as coagulated albumen. According to 

 the analysis of Fourcroy and Vauquelin, ox-bones are composed of decomposable animal 

 matter 51 ; phosphate of lime 37*7, carbonate of lime 10, phosphate of magnesia 1'3 ; 

 total 100. 



2185. Horn is a still more powerful manure than bone, as it contains a larger quantity 

 of decomposable animal matter. From 500 grains of ox-horn, Hatchett obtained only 

 1-5 grains of earthy residuum, and not quite half of this was phosphate of lime. The 

 shavings or turnings of horn form an excellent manure, though they are not sufficiently 

 abundant to be in common use. The animal matter in them seems to be of the nature 

 of coagulated albumen, and it is slowly rendered soluble by the action of water. The 

 earthy matter in horn, and still more that in bones, prevents the too rapid decomposition 

 of the animal matter, and renders it very durable in its effects. 



2186. Hair, icQollcn rags, and feathers, are all analogous in composition, and princi- 

 pally consist of a substance similar to albumen united to gelatine. This is sliown by the 



