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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 calcereous, they will effervesce with acids ; if sili- 

 ceous, they will be sufficiently hard to scratch glass ; 

 and if of the common aluminous class of stones, they 

 will be soft, easily cut with a knife, and incapable of 

 effervescing with acids. 



3. 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 neces- 

 sary 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, vegetable and ani- 

 mal matter, and the matter soluble in water. This 

 may be effected in a way sufficiently accurate, by boil- 

 ing the soil in three or four times its weight of water ; 

 and when the texture of the soil is broken down, and 

 the water cool ; by agitating the parts together, and 

 then suffering them to rest. In this case, the coarse 

 sand will generally separate in a minute, and the finer 

 in two or three minutes, whilst the highly divided earthy, 

 animal, or vegetable matter will remain in a state of me- 

 chanical supension for a much longer time ; so that by 

 pouring the water from the bottom of the vessel, after 

 one, two or three minutes, the sand will be principally 

 separated from the other substances, which, with the 

 water containing them, must be poured into a filtre, 

 and after the water has passed through, collected, 

 dried, and weighed. The sand must likewise be 

 weighed, and the respective quantities noted down. 



