345 



subsoil 64 volumes. It will be remembered that De Saussure found 

 that the most impalpable powder of boxwood charcoal only ab- 

 sorbed 90 volumes equal to itself. Another cause of the extreme 

 fertility of these soils is thus brought into evidence. 



From this the experimenter proceeds to the determination of ab- 

 sorption or withdrawal by the soils of inorganic substances in con- 

 tact with them, and in solution ; experimenting on ammonia, chlo- 

 ride of ammonium, sulphate of ammonia, nitrate of potass, phosphate 

 of soda and silicate of potass, and determining the proportions 

 both of acid and of base withdrawn. The methods by which he 

 proceeded are described with reference to each of the above salts. 

 In several cases the acids and bases are not absorbed in the propor- 

 tions in which they constitute the salts. These very curious and 

 suggestive results are graphically given as well as tabulated. The 

 labours of various other chemists in this direction are referred to 

 and discussed in reference to those of the author. 



Professor Mallet then refers to what he denominates the mechanical 

 analysis of the soil, pointing out the necessity, in all agronomic deter- 

 minations, of finding, by methods admitting of comparison with 

 distant soils, the texture, coarseness, or fineness, &c. of the constituent 

 particles. These results are given in eight consecutive comparable 

 tables. Each soil was separated into six solid portions and the 

 remaining water making up its total weight viz. into the material 

 passing through sieves respectively offering 36, 100, 400, and 1600 

 meshes to the square inch, and into suspended matter of two de- 

 cantations. 



The proportion of impalpable material is very remarkable, amount- 

 ing in the best soils to more than 70 per cent, of the whole. Not a 

 pebble or particle almost, exceeding -j^th of an inch in diameter, is 

 to be found in those best cotton soils whose comminuted state per- 

 mits the free pushing out of root-fibres in all directions. 



The purely chemical part of the investigation is then proceeded 

 with. The methods employed for the chemical analysis of the soils 

 are given under the heads of water, organic matter, inorganic mat- 

 ter soluble in water, inorganic matter soluble in hydrochloric acid, 

 inorganic matter decomposable by strong sulphuric acid, and that 

 not acted on by this acid. And the results follow in eight tabular 

 statements, but are of too detailed a character to be brought into 



VOL. XI. 2 C 



