On Ike Analysis of Soils. 31 



?hou!d be divided from ihe puiL- soil till after the water i s drawn 

 off; for these bodies are themselves often hitihlv absorbent 

 and retentive, and in consequence intlucnce the fertility of 

 the land. The next process, however, after that of heatmg, 

 should be their separation,, which niav be easily accomplish- 

 ed by the sieve, after the soil has been gentlv bruised in a 

 mortar. The weights of the vegetable fibres or wood, and 

 of the gravel and stones, should be separately noted down, 

 and the nature of the last ascertained: if calcareous, they will 

 effervesce with acids; if siliceous, they will be suffici-ntiv 

 hard to scratch glass ; and if of the common aluminous 

 class of stones, they will be soft, easily scratched with a 

 knife, and incapable of effervescing with acids. 



VII, Separation of the Sand and Clay, or Loam, from each 

 otJier. 

 The greater number of soils, besides gravel and stones, 

 contain larger or smaller proportions of sand of different 

 degrees of fineness ; and it is a necessary operation, the 

 next in the process of analysis, to detach them from the 

 parts in a state of more minute division, such as clay, 

 loam, marie, and vegetable and animal matter. This may 

 be effected in a way sufficiently accurate, by ao-jtation of 

 the soil in water. In this case, the coarse sand^wlll o-ene- 

 rally separate in a minute, and the finer in two or three 

 minutes ; whilst the minutely divided earthy, animal, or 

 vegetable matter will remain in a state of mechanical sus- 

 pension for a much longer time ; so that, by pouring the 

 ^vater from the bottom of the vessel, after one, t\\ o, or 

 three minutes, the sand will be principally separated from 

 the other substances, which, with the water containing; 

 them, must be poured into a filter, and, after the water hal 

 passed through, collected, dried and weighed. The sand 

 must likewise be weighed, and their respective quantities 

 noted down. The water of lixiviation must be preserved, 

 as it will be found to contain the saline matter, and the 

 soluble animal or vegetable matters, if any exist iu the 

 soil. 



VIII. Examination of the Sand. 

 By the process of washing and filtration, the soil is se- 

 parated into two portions, the most important of which is 

 generally the finely divided matter. A minute analysis of 

 the sand is seldom or never necessary, and its nature may 

 be detected in the same manner as that of the stones or 

 gravel. It u always either siliceous sand, or calcareous 



sand. 



