According to Berthelot and André[70] this new principle is neither an acid nor an alkali nor even a normal aldehyd. It is, in a concentrated aqueous solution, precipitable by potassium carbonate with the production of a resinous substance. Heated with potash it develops a sharp odor similar to the aldehyde resin. It does not reduce the ammoniacal nitrate of silver. Treated with potash and iodin it gives an abundant formation of iodoform, which, however, is a property common to a great number of substances. For the qualitative and quantitative estimation of the odoriferous matter the following process is employed: About three kilograms of the soil are mixed with sand containing a small amount of carbonate of lime and some humic substance; after having freed it from all organic débris which is visible, it is placed in a glass alembic. The soil should contain from ten to twelve per cent of water at least. The alembic is placed in a sand bath and is kept at 60° for several hours. The water evaporated is condensed until about seventy-five cubic centimeters are distilled over. This distilled water is again rectified so as to obtain in all about twenty cubic centimeters. The odoriferous matter appears to be nearly all contained in this twenty cubic centimeters. The liquid thus obtained shows an alkaline reaction; it contains some ammonia and reduces ammoniacal silver nitrate. This last reaction is due to some pyridic alkali or analogue thereof, and is cause for it to be distilled anew with a trace of sulfuric acid which gives a neutral liquor deprived of all reducing action but which preserves the odor peculiar to the soil. The twenty cubic centimeters obtained as before are subjected to two additional distillations and in the final one only one cubic centimeter of liquid is distilled over. The peculiar odor is intensified proportionately as the volume of the liquid is decreased. To this one cubic centimeter, is added some pure crystallized potassium carbonate. The liquor is immediately troubled and some hours are required for it to become clear again. Meanwhile there is formed upon its surface a resinous ring almost invisible, amounting at most to from ten to twenty milligrams of a matter which has not been identified with any known principle. The reactions described above, however, permit of its general character being known. This resinous matter contains the odoriferous principle, the composition of which is not yet definitely known.