J 72 CALCAREOUS MANURES— APPENDIX. 



tion of an earthy salt ; the combination of the geine with the earth is pre- 

 cipitated, and may be separated by filtration, from the supernatant fluid. 

 In the humid state, these compounds are slightly soluble in water. Accord- 

 ing to the experiments of Sprengel, one part ofgeate ofharytes is dissolved 

 in 5200 parts of water, one part of geate of lime is soluble in 2000 parts of 

 water, and one part of geate of magnesia in IGQ parts of water, cold. 

 These same compounds require for their solution, rather smaller proportions 

 of boiling water. After having been completely dried they will no more 

 dissolve. In the air, the base is combined in part with carbonic acid, and 

 the carbonate which results therefrom remains in the state of mixture 

 with a combination of geine, and of a base analogous to a supersalt. The 

 alkaline carbonates decompose the earthy geates ; they dissolve the geine, 

 and leave the base in the state of carbonate. According to Sprengel, the 

 geates of lime and magnesia are dissolved in the caustic fixed alkalies, and 

 in the carbonate of ammonia. Other chemists have not arrived at the 

 same result ; and according to them, the geate of potash, acted on by the 

 hydrate of lime, precipitates all the geine. The geate of alumina is pre- 

 cipitated when a solution of alum is mixed with a solution of geate of pot- 

 ash, or of ammonia. This compound is dissolved in 4200 parts of cold 

 water. In the moist state it is dissolved easily, and in abundance, in the 

 alkaline carbonates and hydrates, and even in ammonia, /.ccording to 

 Sprengel, it resists the decomposing action of acids, so that it is difficult to 

 extract from it geine exempt from alumine. A combination is obtained 

 having an excess of alumine, by digesting a solution of the geate of am- 

 monia with hydrate of alumina. * * * s- 



Carbonaceous mould. — The substance to which this name has been given 

 has been but little examined. It is insoluble in alkaline liquors. Its color 

 is a brown, almost black. Placed in contact with a body in combustion,^ 

 it takes fire, and burns without flame like spunk. According to the experi- 

 ments of Th. de Saussure, carbonaceous mould combines with the oxygen 

 of the air, and forms carbonic acid gas, and when it is left a long time 

 exposed to air and water, it becomes by slow degrees soluble in alkalies. 

 The acids precipitate it from the alkaline solution, in the state of acid 

 geine. When cold, the sulphuric acid has but little efiect on it. Accord- 

 ing to Braconnot, the nitric acid converts it at a gentle heat to a brown 

 liquor, in which water produces a precipitate of a chocolate color, which 

 possesses the properties of acid geine, and is dissolved without residue in 

 the alkalies. 



Soil (terre vegetale). — It is the mixture of these several substances with 

 the upper layer of the surface of the earth, which constitutes the vegetable 

 earth or soil, properly so called. Arable land is a bed of this soil, placed 

 upon a bed of earth which contains no mould. Its fertility depends upon 

 the quantity of mould which it contains. Growing plants continually 

 diminish the quantity of geine contained in the soil ; and when the plants 

 are carried off from the soil on which they grew, which happens almost 

 always with cultivated land, it is finally exhausted to that degree as to 

 produce nothing. It is on this account that it is necessary to manure land. 

 The matters discharged and left by animals, or the barn-yard manure 

 which is used for this purpose, are by degrees converted into geine, and 

 thus replace the matters dissipated by vegetation. Botanists, who have 

 directed their attention to vegetable physiology, have remarked that the 

 plants vegetate well enough without geine, until the time arrives for them 

 to commence their sexual functions. But as soon as these are ended and 

 the fruit begins to be developed, the plants absorb a great quantity of the 



