Oh the A7iali/sis of Soils. 3 i 



By properly drying and weighing a certain weight of 

 mould, and then submitting it to such a degree of heat 

 as will consume the vegetable or carbonaceous matter 

 to ashes: at the same time, the heat must not be such 

 as will disengage the fixable air fix)m any calcareous 

 matter or magnesia that may be contained in the mould 

 or soil submitted to trial. The difference in weigiit 

 between the dry mould, and that which is thus sub- 

 mitted to the action of fire, will be the proportion of 

 vegetable or carbonaceous matter. 



It is likewise to be done by melting some salt-petre in 

 an iron ladle, bringing the salt-petre to a red fusion, 

 and then dropping into it, by little and little at a time, 

 the earthy matter, taking care previously to dry it tho- 

 roughly. The dropping in of the dried mould should 

 be continued until the complete deflagration of the salt- 

 petre is effected. 



The practical observation to be deduced from the 

 above experiment, is, that the soil or mould which con- 

 tains the most vegetable or carbonaceous matter \v^ill 

 deflagrate the greatest quantity of salt-petre ; or, in other 

 words, that it will require less mould to deflagrate a 

 given weight of salt-petre, in proportion as that mould 

 contains a greater proportion of imflammable matter. 



The presence and proportion of vegetable and inflam- 

 mable matters in clay may, in some degree, be proved 

 and ascertained by the degree of blackness in the colour, 

 which the interior parts of the clay assume, when sub- 

 jected in the fire to a certain degree of heat. 



The existence and proportion of most saline matters 

 in soils are to be discovered by lixiviation, with warm 

 water, and by subsequent chrystallization. 



