THE FARMERS' CABINET, 



DEVOTED TO AGRICULTURE, HORTICULTURE, AND RURAL ECONOMY. 



Vol. III.-N0. 8.] 



March 13, 1839. 



[IVhole No. 50. 



For the Farmers' Cabinet. 



I.IITIE — No. HI. 



In a former communication on the subject 

 of the ajrency and importance of the different 

 earths in the formation of soils, best calcu- 

 lated to produce vegetation in the highest 

 state of perfection, I took occasion to remark 

 that lime (calcareous earth) merited a more 

 particular notice. Its important uses in agri- 

 culture and the arts, cerUinly entitle it to 

 more consideration than any other substance 

 belonging to the mineral kingdom. With a 

 desire, therefore, to invite the philosophic and 

 inquisitive mind into further investigations, 

 it may be proper on this occasion to notice a 

 brief outline of its natural history, and the 

 effects of the various processes necessary pre- 

 paratory to its usefulness and application in 

 agriculture and the arts. 



Lime, in the mineralized state, is usually 

 found in the earth eitiier in the form of car- 

 bonate or sulphate. The former consisting 

 of lime and carbonic acid, commonly called 

 limestone or carbonate of lime. The latter 

 of lime, sulphuric acid, and water, called plas- 

 ter of paris, gypsum or sulphate of lime.— 

 Limestone frequently contains a portion of si- 

 licious, aluminous, and magnesian earths, 

 with metallic oxides. In the purest state that 

 it has probably ever been found, it contains 

 about 57 per cent, of lime ; the other 43 parts 

 consists principally of carbonic acid.* Lime, 

 in the most refined state that it has ever been 

 obtained by art, appears to possess all the dis- 

 tinct characters of metals; consequently, it 

 is considered a simple metallic substance, 

 which has been distinguished by the term 



*A*thi8 suhstance i« of vast importance in agricul- 

 ture, partirular attention will be derotert to it"* con. 

 ■tituents and properties in the cousideration of the food 

 •f plants. 



Cab.— Vol. III.— No. 8. 233 



calcium, which name will be hereafter used 

 j in the further consideration of the subject. 



Calcium unites with oxygen gas with avid- 

 ity, forming an oxide of calcium (quicklime) 

 similar in every respect to fresh burnt lime. 

 In the process of burning, the carbonic acid 

 is expelled, and although about 43 per cent, 

 of the original weight may be lost by the ope- 

 ration, the masses retain their form before 

 burning ; the particles being firmly united by 

 their attraction of aggregation. The oxide of 

 calcium possesses a strong affinity for water; 

 their union is formed with such avidity, that 

 by the rapid condensation of the water in its 

 passage from the fluid to the solid state, much 

 heat is evolved, and a new compound, the hy- 

 drate of calcium is the result. The attrac- 

 tion existing between the particles of the ox- 

 ide of calcium i? destroyed by the change. 



A complete disintegeration takes place, and 

 the whole falls into a state of impalpable 

 powder (slacked lime.) We have now a 

 hydrate of calcium possessing a strong affin- 

 ity for carbonic acid, with which a new com- 

 pound is formed, the water of the hydrate is 

 set at liberty, and a carbonate of calcium, such 

 as existed before the calcination, is the result. 

 Hence it appears that nothing has been ob- 

 tained other than that of reducing the carbo- 

 nate of calcium to a complete disintegeration, 

 which could not have been accomplished by 

 grinding. This state of pulverization is, how- 

 ever, of much importance : each particle be- 

 ing rendered distinct and separate, the in- 

 creasing union with carbonic acid will con- 

 tinue until it arrives at the state of super-car- 

 bonate, thereby very much increasing its ao- 

 lubility in water, which seems to be necessary 

 to prepare it to produce its most important 

 effects in agriculture. Having attempted a 

 brief outline of some of the characters of such 



