234 Analysis of Soils. [Oct., 



matters in their mixed state with oxide of copper, and in calcu- 

 lating the gases produced, but the separation of the proximate 

 principles in their pure state or in definite combinations with 

 certain other bodies. We well know that combustion of the 

 isomeric bodies with oxide of copper, does not enable us to dis- 

 tinguish them from each other; while by other processes they 

 may be readily distinguished. Hence I attach the most import- 

 ance to the latter method. 



In examining the organic matters of soils, we have to operate 

 on a considerable qu^antity of the soil, in order to obtain a suffi- 

 ciency of the matters for analysis. Generally 1000 grains of a 

 soil is a sufficient quantity to operate upon. We first ascertain 

 what matters water will dissolve from the soil by digesting the 

 soil with w^ater at 98 deg. F., for some days. Then filter and 

 evaporate the aqueous solution to dryness at a steam heat or under 

 the bell of an air pump with sulphuric acid placed in a shallow 

 dish below it to absorb the vapor. By a peculiar apparatus of 

 my own contrivance I am enabled to apply a steam heat in vacuo, 

 and thus to evaporate any solution of organic matter with rapidity. 

 The various salts and a certain proportion of the organic acids 

 are dissolved out from a soil by water. They are separated by 

 processes such as I shall describe farther on. 



Having dissolved all that water will remove from the soil, we 

 next digest it in alcohol, which removes a certain proportion of 

 the organic acids and extractive matters. This solution is ana- 

 lyzed in a similar manner to that of the aqueous solution. 



After removing thus all the salts soluble in water, and the or- 

 ganic substances soluble in alcohol, we digest the soil in a solu- 

 tion of carbonate of ammonia, which decomposes all the organic 

 salts, and takes up the organic acids, which readily unite with 

 ammonia, while its carbonic acid goes to the bases and converts 

 them into carbonates. The vessel containing the soil and car- 

 bonate of ammonia is slightly stopped or covered with a cap of 

 paper and set in the drying closet, and kept warm for twenty- 

 four hours at least, when the dark copper colored solution is 

 poured off into a filter, and more solution of carbonate of ammo- 



