72 CHYMISTRY APPLIED TO AGRICULTURE. 



every year, and is productive of good results. This lime 

 is, undoubtedly, less active than that which has been 

 slacked by vi^ater ; but it requires fewer precautions in the 

 use of it, and is not liable to so many inconveniences. 



When lime has been acted upon by the air, till it is 

 reduced to the state of an impalpable powder, it is used 

 with great advantage by mixing it with dunghill manure ; 

 it serves to correct the acidity arising from the decompo- 

 sition of certain portions of this, such as the mash of 

 grapes, 6lc. &c., and it absorbs the juices that would flow 

 off and be lost, or would be too rapidly decomposed ; it 

 likewise fixes the gases, which would otherwise ascend 

 into the atmosphere. This mixture spread upon the fields 

 excites vegetation, warms cold soils, divides those which 

 are compact, regulates the fermentation of manures, an(i 

 furnishes to plants, gradually, and in proportion to their 

 wants, the nutritive principles with which it is impreg- 

 nated. 



Lime slacked by air does not entirely lose the property 

 of being soluble in water, and when used it is carried into 

 the organs of plants by that liquid, producing those good 

 effects which arise from the employment of saline sub- 

 stances, in small quantities. 



Limestone saturated with carbonic acid, though it may 

 be reduced to powder, does not produce any of the good 

 effects arising from the use of quick-lime, or of that which 

 has been slacked by air. Its almost sole use is to divide 

 compact earths, to facilitate the passage of water through 

 them ; and to dispose them to yield more readily to tillage. 



Limestone often contains some magnesia, which exer- 

 cises a singular power in modifying the action of the lime. 

 M. Tennant obtained from 20 to 22 per cent, of magnesia 

 from limestone, in which the lime was in the proportion of 

 only from 29 to 31 per cent., by throwing upon this mix- 

 ture a little more nitric acid, diluted with water, than was 

 necessary to saturate it; the liquor remained turbid, and 

 of a whitish color. 



I have always observed that all earths, of whatever 

 nature, containing magnesia, render the waters covering 

 them whitish; and that the agitation-jof these waters by 

 the wind takes from them all their transparency. When 

 such waters form ponds or pools, they are called white 

 waters. 



